National Plumbing Code Section a Water Supplies
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Transcript of National Plumbing Code Section a Water Supplies
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SECTION A HOT AND COLO WATER SUPPLIES
149
Page Number
Pipe Sizing Assessment of probable demand Assessment of required flow ralet EQuivalent pipe lengths Loading units Loss of tJoad at point ol delivery. L..oss of head Uuough belhtalves and stopvalves Relative. discharging power (l( pipes
18bles A1 Recommended minimum rates of llow o1 varlou~ appliances or
fittings · A2 A3 A4
A5
"' A7 1>8
""
Loading units Equivalent pipe length Loss of hsad thmugh draw-off ISp5 expmssed lliS equivalent pipe lengths Loss of head through draw-of!· taps (metres) Loss of head through laps and equivalent pipe lengths Flow rates at Hll .. 1 Number of outlets at 100% demand at lull flow conditions Average water consumption of domestic and commercial apptiances
Graphs Al Pipe si:ting chart, copper tube to BS 2B71 Table X J>.2 • Pipe sizing graphs, heavy gat~~anized steel lubes to BS 1387 1<:3 • Head loss through ballvalve ormces· M Head loss through stopva/ves
Hot Water Storage Method of asses.stng recoveryJstoraga relationships for hot water storage vessels
Figures A1 Demand patlern histogram A2. Storage make-up ratiO curve
Tablus A10 A11 A12
Cold water slofags In bulk:llngs Asse-ssment of hoi wator dQmand and :!l"klrage requirements Peak hourly loads
Sizing of Primary and Secondary Circulations Circulating pressure Hot water distributing pipes Maximum permissible lengths o1 uninsulated hot wal6r draw-off pipes Primary drculadon pipes Secondary circulation pipes
nmie A13 Density d water
Pumped Hot Water Systems· Figure ~ Recommended pump positioning lor hot water clrculelions
Water Quality Acoustic and vibration In plpeo.vork OefOnised water Distributed loads on stfii ]olsiS Operation ot a base excha~ water &lftener Softened water
Figure A4 Re-circulation delonlsatron system
Tables A14 A15 A16
Distributed loads on steel joists (I} Distributed loads on st'lleljolsts (iO Distributed loads for spans up to 3 metras
Outward Thrust In Pipelines Due to lntermil Pressure 1/alues of K for various bends ...,,.
A17 Bearing capacity of soils
Groph A5 External t~rust devel~~ in pipelines.
260
1-6
1 1. 1 2 2 2
2 2 2 2 2
2
3 4 5 6
7-8
7
·7 8
7 7 8
8-9 8 9
•• 8 9
8
9
·9
9-12 12 10 11 10 10
10
, , , 12·13
12
13
13
Page Number
Acoustic and VIbration Control Acoustic kousUc bridge Acoustic transmission Asralion or water pipes Float operated 118lve oscillation Float operated valva water noiSe Impact noise In sanitary fittings Pump noise Tap water OSCillation (valve bounC£1) Thennat movement noise Water hammer Qnipulslve noise) Water flow noise Water terminal fittings
Water Hammer Basic design principles Shock pressure rise Sizing Of hydro-pn'llumalic accum~•atOfS System proteclioo ·
Ayures
·I
A5 HydrO-pneumatic accur!MJititor AS Accumulator sizing
Tables A1B P«umutat.or sizing 0) A 19 Accumulator sizing (IQ A20 Flow rates !rom copper tubes
Graphs A6 Velocity of shock wave/pipe wall thickness A7 Hydro-pneumatic accun:1ulator selection chan
(s"1ngle units) N3 Hydro-pneumatic accurnulator selection chart
(multiple units) NJ Hydro-pneumatic accumulator selection Chat1
(5-SOmm pipe run)
Inspection and Testing of Water Mains. and Water Supply Syst_ems Cold water systems HOt Water systems Sterllizaton of cold water systems
Prevention of Contamination of Water by Backslphonage or Croils Connection
Backflow Prevention Devices Check valve . Pipe interrUpter "Jype A air gap Type 6 air gap Vacuum breaker Upstands on supply and distributing pipes
Figures A7-A12Examp/es of back1Jow p1'e\len1ion A13 lWe A air ga·p A14 "JYpeSairgap A15 Spring loaded check valve A1B Pipe Interrupter A17 Vacuum breaker A18-A19 Back11ow protectiOn by the use of upstands
Table& A21 RequirameniS for backfi,_JW protection A22. Required dimensions fot "fYpe A air I:JS.PS
Protection of Draw-off Taps, Hose Connections, Bidets, Clothes and Dishwashing Machine~ and Cisterns Acceptable methods ol backllow p~:otectlon al points of use or delivery of water ·-Draw-off lapt9 Primary healing circuits and 1eed C\Sierns Secondary backl!ow protection ShOwer hose connections Storage cls1erns Washing machines and dishwashQI'S
Figures A20 Arrangement or a dome;lt"IC cold water ciSiern oomplying with
water Byelaw requlreme:nts for preventing conlamina.tloil of · stOfed water
13-15 13 15 15 15 14
.15 15 14 14 15 14 14 14
15-24 16 16 17 16
16 18
19 19 19
21
22
23
24
25 25 25 25
25-26
2&28
"' 27 27
"' 28 28
.. 'Zl
"' 28 26 27 28
26
"'· 28-32
30 29 28 30 30 29 29 29
30
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Page Number A21 Secondary backllow pmtectron on a common aupply pipe
serving l'NO or more ~Ungs 31 A22 Secondary back!! ow protection on a common distributing pipe
serving two or more dwellings. 32
Tables A23 Air gap dimensions 29 A24 Class 1 risk of contamination from a sub$lanca oontinuoll!lly
or frequently present 31 A25 Cle.ss 2 risk of contamination lrom a substance which may be
present 31 A26 Class 3 risk of contamination 31
Unvented Hot Water Systems Application of Building Regulations Application of Weier ByelaWs Check valve Discharge plpework from relief valves Expansion relief valve Expansion vessel Inlet pressure reducinglllm1Ung valve Una strainer· · Stopva.lve · Temperature relief valva
Figures Ai:!J Schematic layout Of an unvented domestle hot wator
installation A24 Pressure reducing and limiting vaiV9s A25 .E11panslon reUef valve A26 Temperature and pressure relief valve A2.7 Accommodation of expansion water in an expansion vessel;
t~nvented installation A2B Accommodation of expansion wal&r In a cistern A29 Accommodation of axpam;lon water In an expansion vessel A30 Example method Of providing sate disposal of hot water
discharge from safety dev!ces
Corrosion Causes, Effects and Preventative Measures Bacteria Basic theory Contact with dissimilar materials DiH9rentlal aeration Dissolved gases Dissolved salts Fla.v, erosioo. impingement and caVitation ion concentration Organic matter pH Solution potential Stray curJent corrosion Surface effects · Temperature
Figure A31 Pourbalx diagram of Fe-H20 systems
'll>ble AZ7 Galvanic series of metals and alloys in naiufal waters
EffeCts of cOrrosive Environments Aluminium and aluminium allo~ Brasses Bronzes Cadmium Cast iron Copper Copper.and copper alloys Cupro nickel all~ lead Magnesium PlaS1ics and rubber components Soft S01de111 Stainless S1e&ls Steels Zloo
Table A2B Maximum roeommended water ve!ocitle'slor copper tube at
differentlempendures
Prevention of Corrosion AsseS!ilng the COITtlsivity of the local environment Chilled waler systems Cleaning and descaling boJiers and associated pi' ant Cooling waters
32-<35 34 33 33 34
" " 32 32 32 33
32 33,34
33 33
34 34 34
34
35-GB ;g 35 ;g 36 36 36
"' 36 38 36 35 36 36 35
38
37
39-41 36 39 39 38 38 38 38 4(J
40
"'' 41 40 40 40 41
39
41-44 41
42,44 45
42,44
INDEX
Page Number
Corrosion control and prevention External and Internal sys1ems Potabfa (supply), hot and cold domestic wateB PrJmary and secondal)' hN.tlng waJers Steam raising plant
Tables A29 Assessment of condition of ~rcu!ating systems from
analyllca.i data A30 Recommended waier characterislics lor evaporative coof!n-g
A31 A32 A33 A34
towers · Recommended water charac~erisllcs for shell boilers Recommended water characterl~ics lor water-tube boilers Recommended water character~s lor once-through boilers Cleaning and de:scal!ng bol1e111
45 41,44 41,44 42,44 42,44
42
42 43 43 44 45
Welding/Brazing and Soft Soldering/Adhesive Bonding 46-47 .Adhesive bonding 47 Brazing 46 Soft soldering 47 Welding 46.
'lllble A35 Composition of ~ical soh solder-! 47
References 48
British Stendards and Codes', of Practice 48-49
SECTION B DOME$1T/C CENTRAL HEATING ..
1 50·71
Design Considerations Fklw uf water In pipes Heat emission from Insulated pipes Heat emission from p!pes Heat losses through building structures Vertlc&l pipe$
Tables BT Temperatunt and ventilation rates 82 Percentage of heat emission frOm vertical copper pipes as
compared with horizontal Jlipes · 83 Heat emission from lnsulat8d copper pipes 84 Resistance to hot watir flow throu,gh copper pipes 85 Fleststance to hot waterflow at 0.61mJ& through fiHings 86 Heat transmittance coefficients'(\) '~Slue&)
Graphs 81 Heal emission from painted singlE;! horizontal uninsulated
copper tubes to BS 2671 82 Heat emission from unpainted single hoclzontal unlnsulated
steel tUbes loBS 1387
Heating Controls s"Mslng e1em8nts . Timing controls
""""' Systems of Control Boiler air supply. Extemal temperature-rompenssllng controls Frosllhennostats Fuel storage Full control Fully pumped systems . Fully pumped system with 2-port control valve Fully pumped system with S-port control wJ....a Optimum Slart control systems Partial control Sealed systems Ventllatbn of boiler compartment& Ventilation of Jiving rooms zone control
Figures
50-58 53 53 50 58 50
50 ., 53 53. sa 58
51
52
59 •• 59 59
60-65 65 62 63 as 60 so 63 61 63 60 63 65 65 62
Bl Programmer or lime switch cornrd 60 B2 Two-port motorlsedvalve added lcJ eystem 61 83 Fully pumped system wflh J.port ,'ralve control 61 64 Fully pumptjd system with 2·port inotorla&d valves 62 B5 System with 8J!ternli! temperature~ control 62 85 Three stages 01 operation ol an e{panalon vessel 63
----------------------------------~-----------261
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INDEX
Page Number 63
Page Numbor
87 Anangemenl of sealed system compon~nts 'Collar Boss' system Connections from washing machines Depth ol trap seats
98- Connection dlrvct 1rom water supply pipe in accordance wllh M~Byelaw14
Tables
64
. B7 Capaclzles oi6Xpansion WISSelS 64 B8 Air opening sizes 65 89 Minimum free area of ventllallon to rooms where heating
appliances are fitted 65 810 Solid luel storage capacities 65 811 Reeommend!K:l minimum capacity of oij storage tanks 65
E;lectrlc Central Heating Storage Elollers Assessing the existing system Commissioning Control Sequence Converting the existing system Design consideraiions Dry core ballet Dry core boiler capacity Economy 7 tariH Elec1rical supply Existing pipeworl< Heat loss calculations lnstalla!lon-siting lha boiler Plumbing considerations Symem comrols-user Water storage boiler
Figures 89 Cry core boiler 810 Typical e:dstlogsystem 811 System conversion with dry core bo!ler and Economy7
water heaUng · 812 Total ayetem schematic
Domestic Electric Water Heating Central storage sys1em Cylinder Insulation Cylinder size Design principles Economy 7 controller Economy 7 cylinders and combination unlls Economy 7 syslems ' Economy 7 tariff Electric installation Immersion heaters lmmemlon heater arrangements
Figures . 813 Domestic electrlc:lty tariff
814 lmme~lon heater arrangements 815 · Ae<:ommEmded EconOmy 7 systems 816 Economy ?water heating controller 817 Electricity Council Specification for a direct cylindllr eta Elaelrlclty Council speclficalion for an indirect cylinder 819 Economy 7 cylindrical combina!lon unlls 820 · Economy 7 rectangular combination uniiS 821 lnstanlaneous wat11r heater 822 Undersink and overslnk water heaters 823 wan kettle 824 Wiring lnSiallatiOn rortwlnside eotryarrangemeniS 825 Wiring installation for dual element arrangement
lil.ble 812 Specification forimmersl?A heaters
Groph B3 Profile of hot water for a size 7 (120 litfe) cylinder
References
British Standards and Codes of Practice
66·69 66 or or 67: 6S 6S or 66 66 .., 66
"' " " 69
66 .6B
69 69
69-76 69 70 70 70 72 72 72 70 70' 72 70
70 71 72 T.J T.J 74 74 74 74 74 70 75 75
75
71
76
77
Design o1 single branches and fittings. Discharge piPe systems Discharge pipes Discharge units l.alge branch connections ModiDed single stack system Prevention of cross flow Single 5tack system Sizing procedure tor discharge uni~ method Small branch connections S)ack otlsets Stub stacks Termination of dlschargo and vant~ating stacks ventilating pipes and stacks Venlilated 5tack system Vt!ntllated system Waste d'ISPC)Sal uniiS Waste traps and dJscharge pipes
Figures C1 Ventilated system C2 Ventilated stack system C3 Single stack system C4 MOOffied single 318.ck system C5 Connection of waShing i,lppiJancas without_venllng C6 Connection of washing ;appliances with wntlng cr Restricted connect! on ai·ea on stack (i) • CB Examples of permitte'd c'.onnections C9 Restricted connection aooa on staCk (U) C10 ElCS.rnples or p~rm'rtted Connections (50mm parallel branCh) C11 'Collar Boss' fitting ' Ct2 Length and !an of basin waste C13 Air admittance valve
18bles C1 Minimum Jmarnal diameter or traps C2 Maximum capacitie5 ot /stacks flowing quarter lull C3 Discharge units ' C4 Maximum number ol dls.dlarge units allowed oo branch
cftscharga pipes C5 General, guide lor the sizing of ventilating pipes and stacks· CS Discharge stacJc sizing(~) C1 Dischaf9e stack sizing (b) CB Design of branch discha'f99 piP'IS
Grophs Ct Probability graph C2 · Discharge units and I~ rates
Kitchen· and·Laborato111 Drainage Kitchen Dralnege
"""' Backflaw problems Branch discharge pipes Drainage (above ground) Floor drainage Grease traps Materials Pumped installadons Specific requirements Traps l..abomtory Drainage Dilution Distribution lncompatfb!e wastes Radioactive wasta Replacement
Materials tor Above Gni•und Drainage Systems Selection -yypes ol materials
. SECTION C. SANITARY PLUMBING AND DRAINAGE
78·11Jt1'? Inspection and Testing:of Discharge Pipes IJU Airiest
Design of Sanitary Plpework Systems Admission ot: rainwater into discharge slacks Air admittance valves Bands and branches at base of stacks Branch to staek connections Capacities of stacks
262
Commercial or publ!c buildings DweJ!Ings Parlormance cf tasting sys~ems
78-89 Tables 84 82
"" B8
""
C9 Number of appliances to_ be discharged simultanrously for testing stability of trap se.els-<!Welllngs Number of appliances 10; be discharged simultaneously for testing stablJity of trap ee_als-commerclal or publ!c buildings
Copyright by the IP, Wed Aug 22 12:56:47 2001
61 eo eo 82 78 80 B4
" 79
" 79 86
" " 79 63 63 78 78 eo 80
78 78 79 79 80
" 81 B1 81 62 82 82 63
81 84 86
66 66 88 66 89
65
"' 90-91
90 90 90 90 90 90 90 90 90 90 90 91 91 91 91 91 91
91 91 91
92-93 92
"' 93 92
92
93
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Vacuum System
Methods of Waste Collection
Sanitary Accommodation Sanitary accommodation lor disabled people Scale of.provision ol sanitary appliances
Tables Scale of provision ol appliances:
Pag:eN~ber 93
·93. 93-100
100 94
011 Office bulldingS and shops 94 012 Dwellings 95 C13 Accommodation lor elderly people 95 014 Residential hOmes lor elderly people 96 015 Factories · 96 016 Schools and higher educational establishments 97 017 Cinemas, concert halls, theatres etc 9B 018 Hotels · 98 019 Restaurants and canteens 99 C20 Swimming pools 99 021 Art galleries, libraries, museums. places of public assembly 99 022 ·New public houses 100 C23 Marinas and yacht harbours 100
-he Design of Drainage Systems 100-109 ~vmputer programs I 101 Discharge unils 103 Gravity flow pipe design charts 104 Hand calculations 102 Model Watar Byelaws 103 Percentage gradients 102 Rational Lloyd-Davies Method 101 Theory 104 'ryplcal computer program 101
Figure C14" Typical computer program 102
Table
C24 Average water consumption lor varying households
Graphs C3 Design chart, 100mm pipe {i<s .. 0.6) C4 Design chart, 100mm pipe (K, "' 1.5) CS Design chart. 150mm pipe {K, "' 0.6} C6 Design chart. 150mm pipe (Ks = 1 .5) c:! Design chart, 250mm pipe (K, :c 1.5)
Sewage Pumping Systems Designing pipework Systems tO resist seismic disturbances Drainage charts for obtaining the HMO Drainage definitions Drainage formulae Dipework suspension
"!!cautionary conSiderations .... ystem Integrity-Ventilation of pumping Chambers
Figures Cts Pipework suspension, co-axial C16 · Con_crete duct (radioactive protection) C17 · Spring hammer CTB sway brace
Table C25 Proportional areas and depths ar. HMD's
Below Ground Drain Renovation Cast iron drainage
. Closed circuit television High pressure jetting Renovation Renovation or Renewal?
Methods of Pipe Renovation Cement grouting·with pistons Dtain liners lnsltu liners Uquid resin grouting Pipe bursting Prerormed pipes Sleeved uPVC pipes : . Small nian entry 'eg!il and barrel' shaped sewers Special grouting to individual joints and cf"l!lcks Spraying 1Wo-part c~emfcal grouting ·
103
105 106 107 108 109
110-115 112 112 111 111 113 113 113 110
112 113 113 114
112
114-116 115 118 115 114
·114
116-118 116 117· 117 116 116 116 118 118 110 118 118
INDEX
uPVC spiral relining
Figures C19 Cement and rosin groul!ng CZO lnsenlon ol lnsltu liner C21 Curing !nsltu Rner C22 'Permallne' liner C23 'Renoline' sleeve
Rainwater Systems Calculation mcamples MethodS ol design Gutter outleiS PrevenUon of Ice on roofs Rainfall inlensity tables Sizing charts Sources ol data. Use of gutter tizing charts
Figures C24 Flow chart showing calculation prccE!dura~~o C2s UK mcip. key to rainfall tables · 026 'lce-li!Op' seH regulating heating sysl<lm
labkls C26{a-g} Rainfall tablas CZ7 Estimated eapacilles of outlots for fiat roofs C2B categories of r!Sk C29 Flow rates, square/rectangular ungra_tad gunerouUets C30 Flow rates, circular ungrated gutter ou!lets
Graphs CB Gutter siZing nomogram C9 Vertical ralnwaler pipe sizing chart CtO AeC1angu1ar box guitar sizing chart Ctl ll"apezoldal gutter si:zlng chart, 11o 1 side slope C12 Trapezoidal gutter sizing chart. 11o 1 . .5 side slope C13 Trapezoidal gutter sizing chart, 1 to 2. side slope
Solid Waste Refuse Disposal Design consideraUons On-sita lreatment PipeUne sys1ems Refuse collection Scope
References
British Standards and Codes oU Practice
SECTION D PUMPS AND PUMPING
Definitions and Descriptions Absolute pressure A!mospheric pressure Capacity cavitation Efllcierlcy Friction head Gauge prsssure Net positive- suction head (NPSH) ,.,.., Power and efficiency
·Se!l-priming Static delivarv.head Static head Suction head {negative) s.~ctl~. head (positive). Total delivery head Total head on pump Total suction head (positive) Total suction lift (negmiva) Vacuum Vapour pressure Velocity head
Figure 01 Pumping dellnitions
Pump Types Applications Cenuifugat pump
Page Number
117
118 117 117 117 117
.118-133 119 118 126 133 123 128 118 124
119 122 133
12:. 124 124 126 126
-125 128 129 130 131 132
136-134 133 134 134 133 133
135
135-136
137·142
137-138 137 137. 137 137 137 137 137 137 137 137 137 137 138 138 138. 138
"' 138 138 138 138 138
138
139 139 139
263
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INDEX
Page Number
Positlvti displacement pump 139 Layout
Page Number 156 156 153
. 155 Graph
Main pressura reduction Pump assisted circulation
01 Typical characterisfiCCurves 139
Systems 139-141 Ettecls ol pump on system 140 Packaged systems 139 Unpaekaged component systems 139
Figures 02(a) Open circuli 140 D2(b) Open circuit pressure diagram 140 03(a) aosed circuit 140 03(~) Closed circuit pressure dlagmms lor variOus pump poslUons · 140
GraPh 02 Pump graph 141
Pump Selection 141
Noise 141
Pump Installation 142 Discharge non-return valve 142 Electric motors 142 Foot varve 142 LocatiOn • 142 Piping 142 Relief valve 142 Suction strainer 142 Switch gear 142
British Standards 142
SECTION E PIPED 143·169 GAS SERVICES
Natuml Gas 143-146 .Factors affecllng pressure loss 143
-~~-p- ·~ Gas flow tables 143 Meter house dimensions 145 Pipe sll:lng tables 144 Pipe ~pport labiGS 145
Tables Et Pipe sizing, horfzonlal copper tube E2 Pipe sizing, horizontal steel pipe E3 Pipe sizing, elfect of elbows, tees or bends E4 Pipe support5, Iron/steel pipes E5 Pipe suppo/1$, copper pipes E6 tnduatrialga.s meter sizes E7 lYPicaJ equipment gas consumption figures
144 144 144 145
. ·145 145 146
Liquefied Petroleum Gas Installations 146-152 Building control and planning permission 146 General properties ' 146 LPG bulk tank location and safely distances 147 LPG storage- in cylinders 150 Pipe sizing 151 Pipe sizing tables 152 Stor~ge tanks ~nd fittings 149
Figures E1 Small bulk vessel adjacent to a building 149 E2 Small bulk '-'8SSel at domestic premisus 149 E3 Storage tank dimensions 150 E4 Cylinder storag11 150
Tal:lles E8 Minimum recommended safety distances lor LPG storage
vessels 147 E9 Cylinder sizes t50 E10 Guide to pips slzss lor appliances· 151 E11(a-d) Pipe sizing tables 151
Compressed Air 153-161 Closed cycle cooling 154 Compressing cooling 153
. Compressing the air 153 Cooling the air 154 OIJ'ers 156
264
Receivers • Removing mois~~~re Aolary compressors Separators Sizing compressed air mains Thermo-syphon circulallon
Figure ES . 'JYpicaiiB\'t)UI of a oompr&SSed air plant
Tables
154 154 156 156 153
161
,Et2 Final temperature ol sdlabalic compression from free air 153 Et3 Effect of altitude on Compre~r 110lurrHJtriC efficiency 153 E14 Cooling tank capaclt\es 154 E15 RatiO of compression 157 E16 Resistance of pipe tlttings 157 E17 Fonnula for converting volume of compressed air to volume of ~• m
EtB Relative discharging1capacities of steel tubes to BS 1387 157
E19 Discharge of air lhroiJ9l orifices 158 E20 Receivers lor compritssed air systems 159 E21 Vapour chart 159 E22 Equivalent volume ol' complessed air at common pressure 160 E23 \K)fume of compre~ed air carried by rnedum grade steel
pipes 160 E24 Typical equipment consumption of compressed air 160
Graphs E1 Moisture cantent of air 155 E2 Compressed air sizlr,1g nomogram 158 E3 Compressed air- fajJoratorles 160
.Vacuum 161-167 Bench outlets High vacuum systems Hospital systems
• Laboratory systems Pipelines Pipeslziog Pipe sizing lor ll'ldlvidual chamber work Pumping unit& Siting of pumps
Table E25 Comparative vacuum scale
Graphs E4 Pump sizing E5 Vacuum pipe sizing
Medical Gases
References
British Standards aoo·Codes·of Pmctlce
SE(Jf/ON F FIRE PROTECTION S·ERVICES
Principal Causes of !.'Ire in Buildings Figure F1 Fire triangle
Classification of Fire, Risks Table F1 Classification of fire risks
Insurance Companie!', Role and Influence
Sprinkler lnstallation.s Alarms Area covat&d by sprinklers Automatic sprinklers; design principles Classas of system Combined high velocity systems Coverage ot a sprinkler system Duplicate water supplies Are brigade Inlets General i:lescrlptlon, . Grading of ~em~
164 164 162 163 163 165 165 164 163
162
165 167
166·
168
168-169
170-188
170
170
170
170
170
171·18'1 • 180
176 172 172 160 176 174 176 171 173
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Hlgh velocity water spray systam Medium wloclly systams Olher installa!lons using water drenchers Prassure and flOW requirements Pressure tank Principal components Projactors Proving atwater supplies Risk categories Siting ot sprinkler haads Superior water supprtes Systems using sleam "JYpes of water spray systems Water spray proiector systems Water supplies
Figures
Page Number
179 180 177 175 174 171 179
"' 172 176 17.l 180 179 176 173
INDEX
Carbon Dioxide Systems Application Location application Non-conductivity Safety precautions Storage Testing and maintenance Total flooding ."JYpes of system Uses and limi1aUons
Halogenated Extinguishing l,lgent Systems
Private Hydrants
Pa,ge Number
185-186 185 185 185 186 186 186 186 186 185
F2 Typical sprinkler installation F3 Pressure lank and town main with back pressure valves
171 175 176 176 177 177 176 179 179 179 180
By-pass valves Connections Markings Outlets
187
187 1B7 167 1B7 1B7
F4 Diagrammatic layout of the pipework or a sprinkler system F5 Multiple control system F6(a) Automatic control F6(b) Open sprayer F7 Typical drencher sy~em FB Types of drencher F9 High velocity water spray proiectors FlO Water spray projector systems Ftt ·Arrangement of projectors to protect a transformer
· Tubles F2 Fire OHicers' Committee rl_sk categ.or_ies F3 'Working air pressure for pressure tanks F4 Pressure and IIOW requirements Fs Maxlmu'!l area covered by a sprinkler
Hose Reel Installations Automatic 'on and manual off JoJ.Jtomatic 'on and otf Ara protection discharge from jets Pipework · · Pos!lioning of hose re-els Special provision·water supplies Slalutory regulations Tasting and approval Types ol hose reels Water supplies
Agora FT2 "JYpical a~rangemenl of hose reel system
Table !I F6 Height ol jets F7 Discharge from jets
Dry Risers Inlets Installation Outlets Size and positioning of risers Statutory regulations Testing and approva)
Figure F13 Typical arrangement ol a dry riser
Wet Risers1 Installation
OuUets Pumping equipnlenr Size and posiftOnlng Slatutory regulations Testing and approval Water supplies
Figure F14 Typical arrangement of a wet riser
Foam Systems Application Types ol system; Design data Fixed foam uni!s Foam branch pipes Foam Inlets High expansion foam Mobile foam units Portable axtlngu_ishers
172 175 175 ,.
181-183 183 183 181 182 181 182 181 '183 181 1B:l
182
181 182
183-184 183 180 183. 183 183 184
183
184 184 IS'! 184 184 184 184 184
185
184-185
References
British Standards and Code& of Practice
SECTIONG SUPPLIES
Steam Condensate Design considerations Expansion of a steam pipeline Pipeline velocity In staem mains Separators Strainers Tablos Tmps Trap checking
Figures Gt Ofagrammaticsteammain G2 CondEmsate removal from distribution main G3 Alr venting on distribution line G4 Condensa\19 removal from braocflllnes G5 Float trap with the('TI"'IS,talic air valVe GS Inverted bucket trap · G7 Operation ol tlmetal steam trap GB Strainer G9 S!eam trap checking equipment. Gto Expansion bop G11 Alternative loop G12 Expansion bertows G13 Sliding joint
Table-;.· G1 Steam tablas G2 P~sura factors for pipe sizing G3 PipeUne capacity and pressure drop factors G4 Flow of water In stet~! plpos GS Flow of water ln heavy steel pipe_s G6 Expansion of pipes G7 Heal emission from pipes GB Pipeline capaciUas at specific velocities
Graph G1 Sensible, latent an:ttoral heat in steam
British Standards and Codes oi Practice
.SECTION H PIPEWIORK EXPANSION
187
187
189-200
189-200 193 189 197 193 196 198 189 104 196
189 193 193 193 194 196 196 196 196 197 197 197 197
190 191 192 194 195 197 198 199
189
200
201·207
185 185 Considerations lor Design and Installation 201-207 185 Anchor design 202 185 Cold draw 202 185 Expansion b&llows 2W 185 Flanged units 2o:2 185 · Guides along the remaining pipe run 2CJ7 185 Guides neareS1lhe beHows • 208
Pipe guides and supports 205 Plastic soil and waste pi pea 2<Jl
------------------·--------~~------------~ 265
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INDEX
-Screwed end units Welded end units
Figures Hl TypiCal anchor posi1!ons H2 Expansion loop H3 Expansion bellows H4 Flanged unit cold drciw HS 'Nelded 8fld unit cold draw H6 Anchor lor copper pipework (light load) H7 Anchor for steel plpework {Dghl toad) Ha ·Ugh! to medium load anchor H9 T~plcal duct application · HIO Typical riser appliealion HII Altemative light to medium load anchor H12 Application using angle v.oelded to pipe H13 Typical hea>.y load anchor
. H14 Typical service walkway appllcalion HtS{a) Friction coefficient- poinl CQntact HIS(b) Friction coefficient- edge contact HlS(c) Frielion coefficient- nne contact H15(d) Friel ion .coefflelenl ., face 10 race conlact H16 Pipeline I allure may occur without pipe guides H17(a) Bellows positioned centrally in an axlallnstaUation H17(b) Bellows positioned at end o! line in an aJCiatlnslahation H1B Strap-type guide H19 Strap-type guide with tube roller H20 Strap-type guide With roller and chair H21 Guide using angle rolla~ on box section H22 - Strap-fyJ:Se guide us!ng angle rnllers on box 5E!Ction H23 Tee support with angle guide H24 Tee support with raRer and angle guide H25 Guides for large bore and.tlr high pressure pipes H26 Tub€1-type guide H27 Tube-type guide With rodS H28 Slip-on flange type guide H29 Guides near bellows H30 lr\Stallatlon of additional guides
Table H1 Coefficients of linear eMPansion
British Standards and Codes of Pmctice·
SECTION I DESIGNING FOR THE DISABLED
Introduction
Approaches to Buildings Automatic entrance·doors Dropped kerbs Entmncedoors Handrails Levelframped access Parking spaces Stepped access
Figures 11 QlsaQled logo 12 Hendtail dimensions
Inside Bldldings Door handles Double swing doors Floor.:~ Glass doors and other glasS areas Hazards Internal circulation areas Internal doors Kick plates Level changes Passage ways Sllding doors Spring closers Switches Thresholds
Figure 13 Dimensions - lntemal doors and adjacent areas
WC Compartments in Public Buildings Acooss thro1.1gh lobbies ·
Page Number
2il2 202
201 202 202 202 202 202 203. 203 203 203 203 203 203 203 204 204 204
·-204. 205 205 205 205 205 205 206 2d6 206 20!1 206 206 208
'"" 206 2rrl
201
207
208-216
208
208 206
'" 208 208
'" 208 208
208 208
208·209 209 lOa 209 208 209 209 208 208 209 209
· 2C8 208 2<19 200
209
209 209
~eSs to we Companinents Commercial buildings Entertainment 'laciRties Points to consider for WC's Travel facilit'1es
Facilities for Wheelchai" Disabled Additional faCilities Dimensions OOOIS Hand dryel'$ Hand rinse basin Mirrcrs Restricted space SupPOrt rails Toilels Toilet paper holder wq macerating bolCe:J and we pans INC seats
Figure 14 Diniensions ol we compartments and facilities
WC Facilities for Ambulant Disabled
Washbasin Fittings
WC Levels in Private Fa!lilities Considerations Selection of raised toilet seats
Page Number 209 209 209. 209 209
21().211 211 210 210 210 210 211 211 210 210 210 211 211
210
211
211
211 211 211
Facilities for Private USE> and Nursing Homes 212·214 Bathing Baths and accessories Bath Inserts Bath lilts Baths with built·in seats Bathroom layout Bidets . Di~posal of incontinenCl:l and sanftar,y towels Door$ Drainage Fittings Flooring Grabralls HeaUng Showering Space Urinals
Advanced WC Cubicle [leslgn for Wheelchair Disabled
Central Healing for the IJisabled Automatic controls Boilers · Design criteria Gas.billlred Heat emitters OH-peak electric storage heale~
References
British Standards and <:;odes of Pmctice
SECTION J LEGIIONNAIRES' DISEASE
Engineering Implications ApProVed materials · Cold water storage sys1erns and tanks Cooling towers Continuous chlorination plant Domesf1C hot water caloriflers Duties of the mainlenance departmenl Humldirlers Oulbreak, control Slagnant wa1er positions -occupied Stagnanl water positions- unoccupied Thorough le$t!ng ol all outlets \Vater softening and hoi water storage systems
212 213 213 213 213 212 214 214 212 214 212 212
212.214 212 213 212 214
214
214-215 215 215 214 215 215 215
216
216
217-220
217 219 217 219 218 219 217 219 217 218 219 218 218
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Figure · J1 HOI water wamtng nat lee 217
References ~0
SECTION K . FOUNTAIN AND 221·224 WATER DISPLAY TECHNIQUES
Design Considerations 221-223 Construction principles Fountain installations Ten lmponant rules Types of fountains and water displf!.YS Watercourse Installations
Figures K1 A simple lountain unit using a submer!lible pump K2 Fountain lnstallil.Uon tncorporatlrig a dry mounted centrifugal
pump 1<3 Fountain Installation with an open underground reservoir
.oe Art of Water Display cascades Construc~ion and maintenance Important aspects of waterfall design Smalllountains water sculptures Waterfall arrangements
AIRFLOW
221 223 221 221 223
222
222 223
224 224. 224 224 224 224 224
SECTION L IN DUCTS 225··231
Duct Sizing Duct fittirigs r!lsistance. EX'tracl ventilation Ideal system ,. ...
225-229 225 225 229
L 1 VanUlation· head resiSiance !aetas (K) for bathroom end we ventilation ducts 225
Graphs L1 Relationship ol capacity of rectangular and circular ducts 226 l2 Relationship oil(, V and head loss for duct fittings resistances 227 l3 Sizing- chan -ventilation ducts lor bathrooms and WC's · 228
"=ans 229-231 .<iatllow fan 230
Centrifugal len 229 Propeller !an 2:30 AegulEnlons and reQuirements 231
FigUre$ ll Centrilugallan 229 l2 Paddle blade 229 l3 Forward curved blade 229 L4 Backward curved blade 229 LS Propeller len 230 L6(a) -Axial.flow tan 230 L6(b) Axial llow fan mounf!ng, non guide "ana type 230 L6(c) Axial !low fan with guide vanes 230 L7 Root moun red supply duct w!lh recirculating damper o:munt 231 La Roof mounted eKlract lan - natural inlet 231 L9 Recommended proportions tor a plain canopy hood 231 l10 Combined supply and extract system wllh propeller fans 231 L1t C~ven\llationfor public rooms 231
.British Standards and Codes of Practice 231
SECTION M · ELECTRIG'.AL EARTHING AND BONDlWG IN WATER INSTALLATIONS
Introduction Bonding Drainage systems New regulations Plumbers' responsibilities Problems With plastics Protective muHiple earthing Supplementary bonding
Figures • .
232-235
Page Number
232-233 232 233 233 233 232 232 233
M1 Protective multiple earthing, meUlod o_l bonding 232 M2 Protective niultip!e earthing, area aleotricity bOard's
requirements for malo bonding 232 M3 Requirements for bonding in domosti~ snuations 234 M4 Sockets and fixed equipment outsid9 main equipotenl!al zone 235
SECTION N CONVERSION FACTORS AND . MISCELLANEOUS DATA
Conversion Factors lbbles Nf Imperial to SJ metrlrJSI metric 10 imperial N2 Pressure ·
Miscellaneous Data "Tables N3 Multiples and sub-mulliples of units N4 Standard wire gauge thickness N5 English zinc gauge thickness
Identification of Pipelines. 'lltbles
236-259
. 236 238
238-239
238 238 239
239-240
N6 Basic ldentilication of colours 239 N7 Colour re!erar.a1s 239 NB Qpllonat colour COde indications 1or g1mera1 building services 240
Building Drawings Lln&s Sequence of dimensioning
Tables N9 Scales lor use with metriC and 1m peri~~ systems N10 Piping symbols N11 Graphical symbols and representation
Maximum Spacing of Pipe Supp,orts llobles N12 Hot and cold wa!er pipes and gas pi pEls N13 Soil and was\e'pipes
Spacing of Pipes lllble
241-242 241 241
241 241 241
242-243
242 243
243
N14 Maximum distance allowable belwoaen centra lines ol screwed s\eel and copper pipes 243
Head and Pressure of Water lllble N15 Head and pressure of water
Hydrostatic "lllbles
Relation of Services to Each otl)er · Thble
Nt6 Relation to other &ervices
244
244
245
245
, .. ·•! d .•....
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INDEX
Page !'lumber
Approximate Weight of Lead Required for Caulked Lead Joints . 245
Tables N17 Cast Iron soil pipes to BS 416 245 N1B Cast 1roo pipes for water, gas and sWiage to BS 4822 and
spun pipes to BS 1211 245
Corrosion of Metals 246 1llbles N19 , The electro-che!Tilcal aeries
Coefficients of Llne11r Expansion and Melting Points
'Ribles N20 MeWs and glass N21 Plastics
246
246
246 246
Definitions of Plumbing Terms Cold water supply · Hot wat<lr supply Sanitation Drainage
Useful. Addresses
·Page Number
247-252 2<7 248 249 251
252-259 Employers' lrade associations 252 Manufacturers' and othertl'a..de a1tsoclafions 253 Prole6&1onal bodies 254 Research and advisory bodies 255 Regional Water Authorities and Water Ccmpanies in England and Walea 256 Fuel and energy ln!entsts 257 Govttmment departments 257 Training bodies 258 li'ade unions 258 Salety oryanlsatlons 258 Overseas 258
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PLUMBIN~ ENG .. NE£RING SERVICES DESIGN GUIDE -·~~~~~~~~~~~---------~---------Corrigendum
Page No.
3
3&4
35
.43
51
52
75
80&81
as
too
104
"119"
120
12-1"
124
125
132
137
143
148
"158
205
228
236
246
Reference·
GraphA1
Graphs At &A2
Column2
TableA3.1
Greph81
GraphB2
TableB12
F~gures C5 & C6
TableC3
TableC22
Column 2, Step 1 (a)
AgureC24
Column 1, step 5, Line 6 Column 2, Step 5, Una 6
Column 2, Line 40
TableC28
. GraphCS
GraphC13
Column 2, Line 30 Column 2, Line 33
Column 1, Table of · natural gaS properties
Column 1, Pole Formula (lmpunlts) .
Column2,Une42
Compressed Air equations
Figure Ht6
Graphl3
TebleNt
Colunm2
Delails
It should be noted that a design velOCity of 4m/s rnay re!sult In noise within \he plpeworl<.
2000 Loading Unill! on AH axis should read 3000.
"Salt' in the first equation should read Na,S04
Below heading 'Boiler Wate(, 'Total hardness;mglllri,terms of CaC03 max' should be shown as 'non-<fetectable" and a rule drawn tosaparal:efrom lhallgureglvan ror. sodium phosphate.
Add note adjacent to the graph lndlcatingthatltshould, be transposed with Graph 82 on psge 52. The existing graph heading Is correct
Add note adjacenttothe graph indicating that It shou1<1 be transposed with" . Graph B 1 on page 51. The existing graph heading Is "'1rrect. . . For maximum watts de~sJty, substitute; 8.5W/cm2 1 OW/cm2* and 1 OW/cm2.
Delete 'Running trap'; substitute 'Tubular trap'.
(1) In spaca follcwlng Basin spray bop etc,lnoert in appllceble columns; 'Washing bowl, a IHra {domestic) 12002'.
(2) Application of both 80 litre sinks should read (cate~ng).
Delete 'minimum' In Table heading; substitute 'optimum'.
Pips roughness should read Ks- 1.5.
Step 2 should read; 'To select category and determine return period, relerto Table C28' .
Table number should read C26(d). Table number should read C26(f).
Delete Tables (a) to (g);substltutaTeblas (e) and (f).
Insert a C Factor of 1 (or 'Pitched roof with external eayes gutters',
Add nolelldjacerittothe graph Indicating thatlt should l'le transPosed wtih Graph Ct3on page 132. The existing graph heading li• correct
Add note adjacent to the graph lndlcatlngthatllohoulcl be transposed wtih Graph CS on page 125. The existing graph headiog ls:correct.
Amend to read: 1 Newlon= 1 kgx9.8t. F.orrnula shouJd.read: TotaJHaad~L+U+~
CV units should read Btu/H3and MJ/m3
WobbnumbershouldreadWobbenumber. K factor is 2340 (0.0071 lor Sl units)
Amandllnetoraad: 'The reslstanoetothaearthshould not exceed 1 x 105,ohms.
TheJ>ressure drop(psl) equation together with the explanatlonofV shOuld be reposiHonad at lha botto., of column t and raplacad with the Pressure drop (bar) equ1Hon.
Delete 'Bowling lorce';subsutute 'Bowing force'.
Units for Airflow rate should be cubic mtsec.
Metrlc to lmperlaJ column: 1 tonne should read 0.984~! ton.
Column heading should read: · · 'Coefficients or Linear Expansion and Melting Points'.
!'Jovember 191!9
------------,--~~~~-----~---------The Institute of Plumbing 64 Station lane. Hcmchun::h, Essex RM12 6NB Telephone: 04024 ·72791.
JW : ··Copyright by the IP, Wed Aug 22 · 12:55:09 2001
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Section A Hot and Cold Water Supplies
Pages
1-49 Pipe sizing; hot water storage; sizing of primary end secondary circulations; pumped hot water systems; water quality; outward thrust in pipelines due to internal pressure; acoustic and vibration control: water hammer; inspection and testing of water mains and water supply systems: prevention of contamination of w·ater by backsiphonage or cross connection; backflow prevention devices; protection ol draw-off taps, hose connections, bidats, clothes and dishwashlng machines end cisterns; un'lented hot water systems; corrosion causes, ~·ffects and preventative measures; effects of corrosive .environments; prevention of corrOsion; welding, brazing, soft soldering and adhesive bonding; references; Brttish Standards and Cod~s of Practice.
Section B Domestic Central Heating 50-77 Design considerations; heating controls; systems of control; •lectric central heating storage bcilers; domestic electric water . :eating; r.eferences; British ?tandards and Codes of Practice.
Section C Sanitary Plumbing and Drainage 78-136 Design of sanitary pipework systems; kitchen and laboratory drainage; materials for above ground drainage systems; inspection and testing of discharge pipes; vacuum systems; methods of waste collection; sanitary accommodation; the cJesjgn of drainage systems; sewage pumpirig systems; below ground drain renovation; methods of pipe renovation; rainwater systems; solid waste refuse disposal; references; British Slandards and Codes of Practice.
Section D Pumps and Pumping "137-142 Definitions and descriptions; ·pump types; syslems; pump selection; noise; pump installation; British Standards.
Section E Piped Gas Services 143-169 I . .
Naturaigas; liquefied pe!roleum gas installations; c:Ornpressed Jr; vacuum; medicaJ gases; references; British Standards and
L:odes of Practice.
Section F Fire Protection Services 170-188 · 'Principcil causeS of fires in buiidin9s: classification of fire risks· sprinkler installations: automatic sprinklers; risk categories; classes~-system; water supplies; grading systems; pressure and tloo.y requrre'!lents; proving water supplies; fire brigade inlets; slz1ng ol spnnkler heads; area covered tJi sprinklers; multiple controls; other Installations using water; systems using steam; hose reel l~allatlons; dry risers; water risers; foam systems; carbon. dklx1de systems; total flOOding systems; halogenated ~~~gUishJng· agents systems; priVate hydrants; references; Bnt1sh Standards end Codes of Practice.
. CONTENTS.
Section G Steam Supplies I
189-200
Steam; condensate; steam traps ; and separators; British Standards and Codes of Practica
Section H Pipework Expa,nsion 201-207 ' .
Considerations for design and installation; cold draw; anchor design; pipe\rork systems 1\<lfklng UJ/der test condn!ons; pipe guides and supPO<ts; expansion bello~; plastic eoil and waste pipes; British Standards and Codes ofl Practice.
Section I Designing for" the Disabled 208-216
Approaches to buildings; inside buikfl\tgs; we cOmpartments in public buildings; access through 1\lbbii!S; WC faciiHies lor wheelchair diSabled; we facilities lor ambulant disabled; facilities for private use and nursing homes; ad~:anced WC cubicle design for wheelchair disabled; central hej>ting; references: British Stantlerds alid"Codesof Practica
Section J Legionnaires D,isease 217-220,
Engineering Implications; oulbreek a\ntroi; cold water storag.i :cisterns and tanks; continuous chlorinlttion plant; testing outlats; water softening and hot water storage; s'ystems; stagnant water positions; domestic hot water caJOrifiern; cooling ta.vers; humidHiers; references.
Section K Fountain and Water Display Techniques · 221-224 Design considerations; types of fountalr~ and.waterdlsplay; the art of water display; construction and mair)tenance; cascades.
Section L Airflow in Ducts 225-231 Duct sizing; duct fittings resistance; ideal system; fans; Brhlsh Standards and Codes of Practice. ·
Section M Electrical Earthing and Bonding in Water lnstallatic,ms 232-235 Protective multiple e~rthing; bending( problems with plastics; supplementary· bonding; drainage systems; new regulations; plumber's responsibility;_ Blitish Standa_rds.
Section N Conversion Factors and Miscellaneous Data · · 236-259
Conversion l~ors; Identification of ptp~11ines; building drawings; symbcls; max1mum Spacing of pipe supports; spacing of pipes; head end proosure or water; hydrostatic tables; relation to seJVices to. each olher: approximate weight of 1i1ed required for caulked JOrnts;. corrosion of metals; coefficients of linear exparislon· delinition or plumbing terms; useful addresses. •
Copyright by the IP, Wed Aug 22 12:55:10 2001 "l
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PIPE SIZING · Assessment of Required Flow Rate
. The minimum recommended rates of ncr.v at various appliances and fittings are set out In Table A1. Except under very special circumstances, these are rates which are found to be generally acceptable to consumers and the design of a system should provide for thesa delivery rates.
Outlet fittinQ
· wp flushing cistern; float operated valve
we flushing trough, lloat operated valve
Spray tap or spray mixer tap
Bath tap nominal size ~in
Bath tap nominal size 1in
Rate oflcr.Y (lltreslsecond)
0.10
0.15 poj(WC eeNed
O.IJ4 per tap
0.15 hot or cold
D.3o hot or cold
nso·hot or cold
SECTION A Hot and Cold Water Supplies
appropriate loading untt numb<< and adding the resultant totals together, the recommended flow rate can be read from ~raph A1 or Graph A2.
1ible A2 LDBd/llg uni!s
Appliance Loading units lu
WC Hushing cls1ern (911tresl @ Wash basin domestic use 1'h
Wash basln public use 2
Wash basin concentrated use 3
Bath tap nominal size 3f4in . /1o\ . ~-
Bath tap nominal size 11n 22
Shower ;_: ... 3 .
Sink tap nominal size thin 3
Sink tap nominal size %in 10 .
Spray tap "' Notes Shower head 0.10 hot or cold ====----------- 1: ~flushing cisterns wfth single or dual flush contml haliB th,e
Sink tap nominal size lhin 0.20 hot or cold same loading unit.
Sink tap nominal size :~Alfn 0.30 hot or cold 2. The wash basin loading unft ls for pillar taps, and the larger unit is appliCable tosituaffons such tis schools and those offices wham
-~s;..'":::•:::'":::P.::no=m;_ina:::l:::s:::lz:::•_:11:::n ________ o:;.eo::.:.:h:::ot;..o:;r;;.oo;:;l;:.d~ them is a peak perlod,of usa Where spray IBps am installed, an Urinal ftushlng dstems SOlVed '-o.oo4_perp.;,.hi~D~:::> equivalent conffnuousdemand (}/ a04 !Map should be assumed. ~~~~~~~-------~~~~~
Notes 1. The draw-df rate from mixer fittings is nonnally IBSS than that 'from two separate taps. The difference may oo disregarried when pipe sizing. 2. The now rata ol shower heads can VBI}' depending upon the manufacturer. Refer to supplier When in doubt. 3. Wh""' the trequencyo! usage otWCs is likBiy to be more than at 60 second inlfwals, flushing troughs am advised. Urinal demand is vel}' low and Is normally disrBf!Brr/ed. 4. Water demand for industrial and process applio~tions should m designed for their full how rate. The domosffc flow tilts obtsiniid by using loading units should, whene appropriate. be added to the required Industrial flow.
Assessment of Probable Demand!
Equivalent Pipe Lengths for Copper, Plastics and Stainless Steel Piipework
· The diameter of pipe necessSri, to. give a required flow rate will depend upon the head avellable',lhe smoothness oflhe pipe used o.a. 1ype of matelial) and the effl""ive length of pipe run. To the loss of head In the actuall,ength of pipe must be adclo>cllhat caused by pipe fittings s!JCh es e,lbows. mos. etc. For conveniellCEI, the latter is usually expressed as the loss In an equivalent length of pipe as set out in Table 1>:3. · ·
Pipe slze {00) copper mm
15
ElboN m
0.5
Tee m
0.6
In hot and cold water installations, H rarely happens that alllhe =22:__~~--'---~-~_:::::_ __ ~-~_..::_:__~-. appUances Installed are jn simultaneous use. 28
0.6 1.0
. For economic reasons His the usual design praclice to provide tor '35 -~~~~-----~=--~--_..::_:__ __
a simultaneous usage less than the maximum' possible..
1.0 1.5
1.4 2.0
Loading Units In most installations, the simultaneous demand can be determined with an adequate degree of accuracy by using the loading unH concept. ·
Althou9h th~ flow rates ~t hot and cold water draw-off points may not be 1denUcal, for practical purposes, the same loading units can be applied to both 1ypes of dr8W.off. In certain Industrial situations where peak usage is possible, the
. judgement of the designer must prevail and a flow rate demand provided in excess of thai Which, in a dOmestic environment would be Considered an adequate simUltaneous flaw rate. ' Thbie A2 sets out the 'loading unH' rating for venous appliances. A loading unh has no precise value in terms otlitres per second. By muHiplying the total number of each 1ype of appliance by the
42 1.7 2.5
54 2.3 3.5
66.5 3.0 4.5
75 3.4 5.6
108 4.5 B. I).
Notes 1. The losses through tees si!OU/d oo assumed to occur at changes or direction only.
· 2. In major hot water distributi~n systems, special finings with significant head losses are oflen• used. For JntonmaNon cin tflese reference sh()(Jid be made to m::.nufitcturers'liteiature. · '
Copyright·by the IP, Wed Aug 22 12:55:11 2001
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---·---------------------- --~---- - --
SECTION A. Hot and Cdld Water Supplies
PIPES/ZING
· Fitting {BS 11l10)• ~·""' Equivalent length of ~ of ·· tap:fully open same d~meter as tap (m61res)
us Copper Galvanlse<l ml~ ~eel
"nin (15mm nominal) blbtap or pillar tap 0.20 2.70 4.00
:Y.in {20mm nominal) blbtap or pillar tap 0.30 a .so 5.75
1in (25mm nominal) ·o.ao bib tap or pillar tap 20.00 13.00
~Some patented draw-off tap's have a loss of head much higher than BS 1010 fittings.
Loss of Head at Plllnt of Delivery In calculating the diamete(· or a pipe to supply an lndMdual fitting, the loss or head through the draw-off or deiM1ry wive should be taken into account. A tabla or head losses through draw-ofltaps Is given in Table AS. Foreas)rcalculation, a table of the loss of head through draw-off taps exjnessed as equivalent pipe lengths Is given in Table A4.
Loss of Head through Bailvalves and Stopvalves The loss of head through ballvalves, which can be very high, and stopvalves vanes with the r;ateot now, It is usually IIJOie convqrien! therelore to deduct the less or head through these fittings from the avaJiable head. The loss I of head through ballwive orifices of various sizes Is gM1n by Graph"" and that through stopvalves by Graph A4. . ·
Tlrbte AS LDu of held thm(1gh d-mpr (meiJesJ
FittillllS (llS 1010) . Discharge rare in Vs 0.075 0.12 0.15 0.20 0.22 0.30 0.35· 0.47 0.55 0.60
'!.lin bibrap 0.185 0.365 0.52 0.75 1.1 1.8
'Ain blbtap 0.21 0.33 0.45 0.75 1.1 1.4
tin blblap 0.45 0.70 0.90 1.2 1.5
•hln pillar lap 0.24 0.40 0.52 0.70 0.80
l'ln pillar laP 0.24 0.30 0.40 0.50 0.70
Tap Aaw rate Loss a! Equivaont pipe head length
V:; m m ' 86541213
Nominal size lf.zin 0:16. 1.0 7.0
Nominal s~ :y.dn o:32 1.0 13.5
•Head loss for. staled flow r:etes are typieal and may vary with taps of different manufacture. .
· Relative Dischargirng Power of Pipes From the pipe sizing graph i1 can be seen that at HIL • 1, the How rates shown in Table A7 occur.
llrble AT Flow 11m II HA. := 1
Pipe size (OD) copper · mm
15
22
2
Flow,a,es Vs
0.44
1.40
!ible AT F1ow 11t.ut /IlL= 1eoot'd
_28
3S
42
54
76
2.70
4.90
8.00
16.00
. 45.00
Exp~ as a ratio of tha 15mm draw-off rate we Obtain the following tabulations: Jib/1M Number rrtoullellat 100% Amllnd It fuN Wow CGIIIMicnl
Pipe sile (00) Fla.v rare Ratio No.of oullets mm Vs ·to oo·supplied
15 0.44 1.0
22 1.40 3.18 3
28 2.70 6.13 . 6 ----35 4.90 11.13 11
42 8.00 18.18 18
54 16.00 36.36 36
76 45.00 102.27 100
Jibls All A- 11t1frJr coMUmpllon of tiomBdic and lllNiliiMICJal app/laroca .
Appliance
we {normaJ RUSil)
Wash basin
Bath
Shower
· Clothes washing me.chlne
Dishwashing maChine
Domestic waste disposal unit
Bidet
Installations
Jt.oerage water COilSt1!TI¢ln (hot and cold) rrtrestoperation
9
6
80-00
4per inlnute
60-180
1Q-15 per minute
6 !
Domestic Jitreslday/person serwd
we nushin:.g __________ as ______ _ PersonaJ Washing and bath"1ng 25
Laundry 13 -'----'------
Washing up 10
Car washing and garden use 3
Drinking, k>Od preparation and cooking 20
Offices •
we flushln!~ woroen - nonnal flush 12
we fiushin1~ women - dual flush 9
we flushin!~ men - urinals provkfed 5
Urinal flushing: 3 flushes/hour- 24 hour day 14
Urin}l] flushing:. 3 flushe&lhour- 8 hour d:::"Y.:____s _____ _
Sanitary tovrel disposal by macerator . 2
Hand waMr.ng: nonnaJ taps 11
Hand washing: spray taps 5
Copyright by the IP, Wed Aug 2·2 12:55:11 2001
SECTION A Hot and Cold Water Supplies
Gt1ph ·~---E""; I
~ \_! I\ \ Lr-
' r r~. v v 2DO
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I J: 1 8 ·L)
n,J· l~ j\j , L lc_
)11:~-, ' t .. > u
P:l rcJ n,, I , 'j l~~
r.j I I
u·
0
6 0
4 0
3 0 r---
o''-15
\ r-~~
10
B_, 6
4v
3 . v 2
1.5
1.0 L
0.8
0.6 ~
0.4
---p ... _'\
I'\- ~ .').
\ ~ \ ~·---~ .. ~- )> 1~-
\ I ,. , l"'~-'' \•- '\ <:Y"~ ~
,..,.v '· 1:0~ \ -
L_ v-~ ~I"' r\ ~ ' cPL
.,... ~
v. L '-· ~ ~ ....... ~
2_, r- ! ,,
10
L v 1\ f--V
• I'~" -~ ~~' v LV ~I-"
-, v ,.- v r "~r- I"
<!""_
/ L' . J
-- ~---k:: 1-' Jj.
/ 1.--" X
~ ,\S ~r-~- "" '\.
·.-
' L ' ........ v ~ L v
v-x:- v~ i ~.."' '/
s ~ .>(
y~ \
.... ~ ~
_d1 L_ --'-v ~ r"' 1'. ~~ 7 " ~ "
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IL ~ --:),.
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y
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.....r' ~
\ ...6: ...... '
L \
~
v ~ v
~ v -l.
e. ~
I' I
v r ~ 2 v - r;
1'..
8 000
5 DOO
-2 DOD
1
1
500
000 00 8
-~ 4 00~
200
1 DO
70
50 40 30
20
j
v v r f-"1'' ' L ' 1~~ . ~L- '. 0.3
n~ u] LJ
', :J . 'I u
~ _.....,
a·2
0.1 sv L /
0~ 0.1 £
0.08 /
o.os"L 0.05
0.001 UD02
v v L
I"
0' r
~r-
.. IL _...., D.D05
--
v f'\ ~ I"_ L. ~
]X:: r
iL""' / -\
"\
.J. I' 1\.
L _, 0.01 0.02 0.03 0.05
Head loss in metres per metre run
,~<1\io' f/\
_-'\. --. U10
'2: ~
I'\ ~
["\ _"\
v \
~ -, I~ ~
10
5
3
w •.
. 0.20 U30 0.50
----------~-----·-------------------------j .3
~ Copyright by_ the IP, Wed Aug 22 ~2:55:11 2001
·--------·- .. . ---------u SECTION A Hot and Co>ld Water Supplies
Gl»Ph A2 Pipe slzlllfl Dfal!h, Ileal')' galnnlud !18611ub1Js Ia 8S 13117
200
150
100
BO
I\- \
\ '
I j\ !
' '
~-I I
. \!
~ t\ I - '\
. 1'\ ~w··
! I • _'\
I\ \ I ' '""" \ r
60
I ' j\ : I '
\
~ 4
3
oj\ 0
. "\ <OI,
r;,<" I l\ .;:~ - --
\. I' ~~:\ ~ '!> ': \ 0 '!>1~'" ~.I I,. i ~l!- !"'
51 ,\ -~ /
2
\ l'
I'>-~
I
' '
l;...-
~ ...... ., ~ .....
l \ -~~ h: I~'.> ((! ·-v· ·, ~ •:, ...... vl\ , 0
8 ~
e""' •
4 /
3 ........ 2v,-. I
~ ~1 .5 v
.0
6 a
0 .6
[........-", ~
a
'o 4v '/ .3
v 0.
_.__: ...- .. I ..)r I \.I.-' I' .. .... ~
. ._ v ..... /' '\
. ' r-: v-~ .-
.....--r L)i.- ....
v ¥ " .......... ~
• _.... ...... ...... ...
i !.-" :t,.......r I--
.. ..... . ..... .... 1[.....- I
/ .· :'"~ .,.........
I :.."\ ~ <§>~ v Y<· ·- \.
.&
v v ~"',
..... I ..
_1.
....... _.,. 1' . .... ' y
' ..... ~ I' / 2~-'.
/, .. ~. v 15 ..... 0. v 0 0.1
0.08
aoo 0.0
0.001 5
...... ..
./ .....
a002
...... r-· vr I
!..-' ,!;"
'I" 0.005
v '. i v \
.L'
A 0.01 002
, .. I"'" I"
~ v l/' [\
k [;'
~-~-~~ t~
' ..,.. ..
I'\
~ ..... P" ~
~ ~ ~~
I' \
!,..-
...... '\
• 0.05
' I - vr /
I
./ / I
v !..- v / ! ' /
.I JV :.,..~-'! I ./:"" 8 000
! IK I I
:.,.. I -, . : ..........
I :vl' . ~ 1.--;.- :.)..
-:;.. \.
/ . \'V ..........
r, "", \11\l)
~~ v
v ~ >VI ;, ~ r '
1..- '
--b--' r, ~
• v !--"
II ..... ~~
~ 1.- \
'\
' I
j..../
v " ~
' .
...........
./
"~
' ·~·~ ..........
i\ .
k
---Lt.
~ ~
""' ~ ......
.L_-
..... r' ~\.
5 000
2000
1
1
500
000 600
j;l
" 400 ~ ... ,/
~- -~
200
' v I'
~ __\ -, ·'i'i ~ .... !'
I\ \
'\
1 00
70
50 40 30
20
10
5
3
w,.
0.10 - 0.20 0.30 0.50
Head loss in metres per metre run .
.-.
~--~----------~--------------------4
Copyright by the IP, Wed Aug 22 12:55:12 2001
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i. i ....1 ~
!L-1 •...I '
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' l u ' ...
1 u D ,.j
U ...
I 1:1
r 1 i I i I
1:;1
( l ' I
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tj
r 1 : I 8 [ l ~ r ' r I 19
1
. I I. I ·~.:L..;
n [~' 'ct ..., : r; : j; 'LLJ
n
ln ~L
I} I ,. ( J' 1L
Glap/J A3 H88d toss through baltnMI Olll/$e8
. 10.0 I BS 1212 Standard ballvalves .
Size/pressure Orifice size (mm)-lh"/OW 9.5
8.0
'h" med (1) 6.0 6. 0 'h" med (2) 5.0
v.· high 3.0 3A"IoW 13.0
. 'A" high. 9.~ 4 D 1" low 16,0
1" high 13.0 For larger sizes Setl manutaoturnrs' information
.. . . SECTION A Hot and ColdVVater Supplies
i
j_J !
.. y -
"" + - v L ~ .... -~ I/ v ....
' I·/ v v .L
v
Q 2 I - ~?~~v ~I v
~ .0
'/V·~"~
j:~~ n-\c
n1 J
LJ
n lJ L
[]-. J· u
,_,.
lJ
., .0
... ....... 0.6 ;.;;
L1-o-
k v 0.4 ,,
1--v ,/
0.2 IC v k
/ v
1-' v ·"" l,..-" 0.1
1--t-· 0.08 t-
O.jl6 ---
~' / /
0.04
...... "" / 0.02
0.05 I
' I v...- ~~ v I ~~·· v I [I / . . / ! ,"''~1-- . ,..-';/
'· ..... L v L / v ... ~ L
, .... _;,- • ~ L v '"'""/ ,/
.......... / P' '
""" H"' . ' I' . , ..
v / v '>~'/ v . ~I-" / ~"" v; -~l~:. ' ....... \\i /1 '
l.-"' """ -
~/ ~ / I, v'" ~ v' r-~-' ..,. J...o - I ~ I
v I/ .. .. ~ ""'" v l::i" /
~·/ / )/ I ~ ..... v v ..... ~ ~ -~ ... _ / I v .... .L . /
""" ).;" v
!...-: >·•'Y' .'!>~ ""' ........ ~ I-' v ' 1.- L ,,,./' '· ~ i I/ / /
~v v ''':;I"'
/ _/,
- .£" .... v_j ..... 1--v ~
0.10 ' 0.2 o.:l 0. 4 0.5 Q6 0.8 1.0 2.0 lO 4.0 5.0 · fiO ·
loss of head in metres
'· J
L •. Copyright by the IP, Wed Aug 22 12:55:12 2001
'·
5
'
• SECTION _A . - · -1J1 Hot and Cold Water Supplies
. . . .
10.01=-+::C~C-Lr r-==~c--=-·-cf--=.:r.::JI::r::. :c. J:::.::_,'J J-==-=+-=--=-+r=---=--=r+~-=r-4r::;;j 1-----c-, --1-Hi__ , .. --- . -+ : ---+-..:-~: ~~ -1 , -- ..... r 1--i-++- 1--l---'---'-! . . . . L_[__j__ I_ 1- · · ...- '
I I + . I i ' ' I ' ...<" I
m- .1 __ __ .11""'- , __ - I , __
i I ! II ! I i ~ill i ...-/~" Y: 1 2.0 I :--, ---~:7/ I . 7LJ__ .
[ i " j :7 . I 1~~ i ,/ ~ vi: 1.0
i \ '+A I J_.,~ ~~ ! /l./1 . I L,. , , ~ _. ... ·'"'~ ~~ 1 j.·~n, , . _ .v _, . '/' . ~" I/ r-ri· I io'>#/ . · . . /' ---
8 ! . Y· I : ~-, .... \~...A I ; . ·,1 / -· -- l
~o. I y ~ / I --;;;. ,---. - ,-rr- ··-: / I 8 : r---t--1 -- -- +--.L...,... ~-[o.s/ '. · ;-[ //L/~. · ~~~--~~/ !;~ -~ I /.... l /I .I / I : v I .A I'
1 o.4 ' - _ .v _ . , ....... - ~,,.....1"1''\-i-----+-'-t--=~"""v---1 1-+-J ~ _ v , 1/ ,_ v..,. ~ .. 1 ~ i )#'/ I !
v I ;..kf : . j . _ /; ! ; , ! i /y ,-.______,--t--J ~ , 'A"~~ I /j_ 1. f/ , 1 I 1 1 / _-I 1
1
.
VII , iJ../\ . v 1 : , • i,liv l . 1· 1 0.2 i ~,.,~ I • 1---H~-- , ~· - . I.
~ ) · 1 xr11 1
. ,
:-1 ~~//~ I II 1
I ·f-1-'+-,! -1-1
, I / . . 0.001-----l--1---+--'--+~....'-+,-~____;_-~-- --j--i-f--,--!'-i---1-+- ---'----+-+' --1
1-J..-1---+.,.jo""q"_--f-. ---1----· +! ~-+--+-+-1-++--i----+----+---+-+--1 ,....,., I i ;I
o.04 ....L..-+--,-+-II-1-!H __ --+--+--+---L---'--
00 /' I I I I jj__._.__ll -1--1--1 i ---'--1...1..-JI 1--1 0.05 0.10 0.2 0.3 0.4 0.5 0.6 0.8 1.0 2.0 3.0 4.0 5.0 6.0
~ of head in ·metres
6
Copyright by the IP, Wed Aug 22 12:55:12 2001
. ) u .[J
[j
0 D 0 u D u 0 u u u u
.u u u u l1 u !··.:
[
'1--·---------r· . L
T
..., •, L
HOT WATER S1DRAGE Except In cases of special hot water demand, the requirements for the storage of hotwatermaybe assessed from Tables A tO and A11.
lilblo A10 Cold wa/er tfllrllflll in buHdlng1 Type of building 1
Dwelling up to 4 bedrooms D'M!IIing more than 4 bedrooms
Storage (!Ires)
120 per bedroom 100 per bedroom
Hostel ____________ soper bed space
Hotel 135 per bed space ·· ~~------------------~~ Office premises wnh canteen facilities. 45 per empklyee Office premises without canteen facilities 40 per employee
Restaurant 7 per meal
~~~-----------------Day School Nursery J
· Primary 15 per pupil
Secondary ~-Grammar Comprehensive . Technical ·
20 per pupil
. SECTIONAM Hot and Cold ~later Supplies •
Method of Assessing Recovery/Storage Relationships for Hot Water Storage Vessels When sizing hot water storage generators, n is lll)po<1Bnt to determine not only the cotrect size but also the correct relationship between l1lCOVefy and storage "' enable the most efliclen! selection of plant to be made. If :too high a storage volume is selected and the recovery rate determined as a time function of the volume, then not only Is the vessel, and heat exchanger oversized but likewise the primary generating plant, pumps,. pipework and controls. The effect of oversizing will wry deP.,nding on the degree and type of building, but wherethedon]estic hot water load repnesents a substantial proportion of the total heating load, unnecessary expenditure, both in capnal and running costs, Is ln110/ved. Where Inadequate storage and ..iciJvery ere provided, then the sy.;tem will not meet the user req~lrements, with the result that 1 costly modifications may be necessary when the building Is occupied and the engineering serVices In daUy use. Whatever the building under consi~ration, a pattsrn of hot water usag~ can be project~. the actual1usage being largely a function of the building population and the type of ectMty that takes place within. In· determining the patterr) of usage, ft is important to
Boarding School
Children's Home or Residential Nursery
Nurses Home
90 per pupil differentiate between the maximum dally demand and the _.:.,._...:.._.:..__-' ... · average daily demand, so that thellmplications 01 the system not 135 per bed space meeting the demands made Upon!it can be recognised, and the
120 per bed space maximum requirements designed for where necessary. To project the demand pattern over the operating period an hour
~N="":.:'::.:"=.g:.:or_:C:.:o::.:"::.:"":::'•:.:•.::c•::."::.' :.:Ho:::m:::•:...__ _____ 1:.:3.:.5.::pe:::r.:bed.::.:_•:::pac:.::::•::.: by hour analysis of hot water usa~ should be made. Taklng'lnto account the building popuiO!ion, the taw/ end type of actiuUy and all other factors which affect hot; water demand, a quantitive : assessment of hourly usage shoulol be tabulated for every hour of the operating period.
Table A11 Atseum .. t of hoi water dlmlnd and sfllrii!IB tequirements . (baltid"" d/11' of-tltfmand dtllfnl -1
Tl'P' cr1 bw~in~ . Max. daily demand Storage . per person reQuirement
per person Colleges and schools litres litres Boarding 114 23 Day 14 4.5
Dwelling houses Low rental 114 see nota•
below Medium rental 114 45 High rental 138 45
Flato (blocks) Low rental BS 23 Medium rental 114 32 High rental 138 32
Factories 14. 4.5
Hoaplblls' General 138 27 Infectious 225 45 lnffrmari$S 68 23 lntirmaMe:i (wHh iaundrtes) 90 27 Maternity 225 32 Mental 90 23 Nurs_es' h~mes 138 45
Hoatela 114 32
Hotela First class 138 45 Average 114 38
offices· 14 4.5
Spol"b pavilions (with spray-type showers 36 36
Restaurant. Per meal 6111ros
•storclge normaJiy a minimum ~f 1141ltres with a 4-hour heat-up period. 1Aeter also to relevant Hospital Building Notes (DHSS) HMSO.. -
For offices and schools, a conffnupus 12 hour operating period may be sufficient, but for other buildings such as hospitals and factories a 24 hour operating pefiod may be necessary. The projected demand pa/fem should 'p. recorded in the form of a histogram profile as Illustrated in Rgure Al.
Flgum At Oe1111nd Jllnem hlriiJQiam
3500
3000
2500
ll2000
~ 1500
1000
=' -
• ' ' •
.
!M...L:I- ~~
o\::c=4LU.UjjjlllilWL=· 0 6 12
500
'18 24 Hours
From the histogram, a series of "!'<lUentlal peak h~rly loads should be calculated fer groups of hours, from 1 hour through to the maximum number of hootS In tlie operating period. The total · hounyloadsshoutd be recorded as !n Tab/eA121ogetherw~h the average hourly load fer each group 9f hours under consideration. On completion of lllble A12, a graph should be drawn using Column 3 co-<Jrdlna1es as the 'y' axii; arid Column 2 eo-ordinates as the 'x' axis as In Figure A2. Unking the CO<>rdlnates for each
' '
7
G Copyright by · th IP W d e , e Aug 22 12:-55:13 2001
.. ~; · · ' SECTION A • . \fl.'-<· .. .Pl.. .
. ~L · Hot and Gold Water Supplies . -~ ..
HOT WATERI. S1lJRAGE group of hours will prod!JCE! a curve, any point of which establishes a specific relationship .Of recovery to storage which satisfies the system requirements, ! assuming of course these have been predicted with sufficierit accuracy in the demand profile.
T<lb/e A12 Peak hourly loads
2 3 2 3 Peak lit res . lilres Peak Utres LH..s hours used , per hour hours used per hour
3400 3400 13 27000 2130
2 6600 J300 14 26300 2021
3 9600 3200 15 29900 1920
4 11600. 2900 16 28900 1806
5 13300 2660 17 29000 1705
6 t6300 2716 18 29100 1616 ----··-··
7 19300 2757 19 29200 1536
8 . 22000 2760 20 '29300 1465
9 24000 2666 21 29400 1400
10 25600 2560 Z2 29500 1340
t 1 26400 2400 23 29600 t286
12 27200 . 2266 24 29700 1237
Figu"' A2 Storage maA·e-up rallo t:UFYe
500
0 ~o--~woo~·-t~oooo~~1~&oo~·~~~~~~ Storage-Hires
it should be noted that for groups of buildings in which similar types of activity take Jllace and which have the same operating period, the shape of the curves will be closely-related;· the-only variable being the quantitive values of the storage and recovery co-ordinates. It shoul~ also be noted that the storage volumes represent net usable Volumes to which an allOWBfJCe should be added to compensate: for stratification and heat losses. The method described is suitable for calculating all types of hot water storage vessels; including off-peak electric heated vessels. The method Is not hovrever. applicable to non..storage generators because the maximum performance of these is determined by the peak system requtrenient per minute not per hour.
8
SIZING OF PRIMARY AND SECONDARY CIRCULATIONS
Tabt& A13 O&ns/ly afllllllllr
Temperature Density ~emperature Density ·'C kg/m3 "C kg/m'
0 999 .. 8 6Z . 982.1 .
• 1000.0 64 981.1 ·iQ 999.7 66 979.9 '12 999.4 68 978.9
'14 999.2 70 977.7 '16 998.9 72 976.6 '18 998.6 74 975.4 20 9962 76 974.3
!22 997.7 78 973.1 !~4 997.2 80 971.8 :~6 996.7 82 970.6 :28 996.2 84 .969.3
:30 995.6 88 968.0 :32 995.0 88 966.7 :!4 994.3 90 965.3 :l6 993.6 92 984.0
38 993.0 94 962.7 40 992.2 96 961.2 •12 991.4 98 959.8 44 990.6 )00 958.3
··-·-----46 989.8 102 956.9 48 988.9 104 955,5 00 988.0 106 954.0 52 987.2 108 952.6
S4 986.2 11,0 951.0 !)6 985.2 120 943.1 ne 984.3 130 934.8 llO 983.2 140 926.1
Circulating Pressure In a 9ravlty heating circuit it Is necessary to calculate the circulating pressure in the system in order to determine the allowable frictioo loss per metre run of effective pipe length.
For any system, this is obtained as follows: CP in Nim2 = 9.81 (D,- Du x circulating height in metres where D, =density¢ water in return pipe and D1 =density of water in flow pipe.· As low pressures are usually expressed In millibars and 1mfbar = 100N/m2, the expression becomes: .
Cp I ) .::9.8.::1:_(,;::0.!.., --=D~I).:cx:,:c::,irc::.:u:..la::tl:.:.ng=he:.::lge:h:.:.t (m Jar = 100
Ex:ample Deterr!Jine the circulating pres sur~ In a system desi~ed for a ~low temperature of 8_200 ana a return temperature of eooc if the clrcula~ing head ls.5m.
CP = 9.81 (963.2- 970.6).x 5 = 9.61 x 12.8 x 5 100 100
CP = I> 18 mbar = 61800 Pa.
Primary Circulation Pipes When the primary circuit to a hot water supply system operates by natural circulation, the si~lng of th~ primary. circulatl.on pipe$ Is carriecf out In the same manner as that used for sizing gravity heating circuits. The circulating head is the vertical dislance
Copyright by the IP, Wed Aug 22 12:55:13 2001
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SECTION A Hot-and Cold Water Supplies
between the centre of the boiler and the centre of the hot water ~orage vessel.
beanngs having no seals to replace. These units will normallx give years of trouble free service. ·
Normally. the temperature or the stored water should not exceed ss•c and the temperature drop between the primary How and return pipes· shoutd not exceed 22"0. For any indirect system with a pump assisted circulation, the temperature drop should not exceed 11°C. ·
Secondary Circulation Pipes Secondary circuits ·may be designed for· pumped or natural circulation, but where practicable they should be designed for natural circulation. Circulation depends upon the heat loss from the circuit, the circulation pressure available and the frictional resistance of the circuit.
Owing to their form of construction, this type of pump can be refitted into the existing main purrlp housing when a replacement motor and rotating element is required. • · The power output of these pumps varies betWeen 40W- 120W, and with a running current of 0.40 to 1.9Amp. The recommended poSition lor a s6condary H W circulating pump Is shown in Rgure /J.3..
Rguro A3 Recommended pump /Hll,utlon/ng ilr hot water cln:uiB/Ians
The f\QIN pipe of a secondary circuli Is also the hot water distributing pipe and should be sized accordingly. The return pipe should be sized so that the temperature drop on the ci.rcuit is not . Cold feed cistern less than SOC and not more than ~c. dependent upon the ·
HW draw-offs
I temperature required at the draw.off points.
Hot Water Distributing Pipes Dead legs to hot water draw-off points should be as short as possible and in no case must they exceed those given beiOYJ.
Maximum Permissible Lengths of Unins.ulated Hot Water Draw-off Pipes BS 6700 gives the following restrictions on· the lengths of pipe supplying a hot water draw-off tap, measured along th~ axis of the pipe from the cylinder or tank or from a secondary circuit. These are: Largest Internal diameter of copper pipe: (.1) Not exceeding 12mm· 20.0m length {2) Over 12mm, up to and including 22mm 12.0m length (3) Over 22mm, up to and including 28mm B.Om length (4) Exceeding 2Bmm 3.0m length In the case of a compound pipe of differing diameters the largest diameter Is to be taken.
PUMPED HOT WATER SYS1'EMS In order to allow for a rapld response to user demands, many large hot water lristaOatrons Include a circulating pump within the secondary circuit.
. Owing to the large amount of alrthat is present in the systems, care should be taken with the pump positioning. The pump should not be fitted in the lowest point of ths secondary circulation plpework because sediment builds up and When passed through the pump could easily damage the beartngs and also cause the pump to sei:ze. · To ensure quiet runnlflg, th8 plpework should ba Qeiierously srzed to reduce friction losses af1d, the pump head kept to a minimum. Adequate spac;e to permit free ventilation arOund the pump Should be allowed. This will also facilitate servicing shouk:J this be necessary.
·lb render servicing of the pump easier, isolating valvoo should be tltted on both the Inlet and delivery sicfe. so that the pump can be inspected Without the need to drain down the system. To prevent ~in to the pump body the pipework on either sid~ should be adequately supponed and care takf!n to line up with the inlet and delivery connectors. The type of pump most sulled to this work Is of canned rotor, bronze or stainl~ steel ~nstruction with water lubricaied
CI~Uiallng p~inp and Isolating valves
WATER QUALITY .
I Secondary cin::uit
The quality of water Is defined by chemical and bacterial analysis and where the end usage is directly or indirectly for human consumption. It should comply \with recognisad standards to ensure freedom from hannful ba~te~a. acute and long term toxic .substances and In addition, the water should be clear, odourless, iasteless and wholesome. The 'International Standards lor Drinking Water' produced by the World Heallh Organisation deline the .toxic limits for substances frequently found in water supplies. In the UK, the Ministry of Housing Report No. 71 (4th edtlion 1969), recommends the bacterial purity standards for w'~ter supplied bY public water authorities In addition to estabflshing procedures to be followed In obraining sampres . Waters which satisfy the quallly standards for human consumption are not alwayssuitai,rle for certain medical, industrial and commercial uses. They may contain levels of trace elements, high total dissolved solids contents, non-pathogenic bacteria, gases and suspended matter which necessitate some form of
'"trea.tme"nfbefore ·the water can be used in activlttes such as foOd and pharmaceutical preparation~ brewing, research, medicine and in many areas where heat gerleratlon and transfer take P.lace. Chsmically pure water has no free Ions; Its hydrogen ion concentration, usually known SS' pH value, is equivalent to the hydroxyl ion coni:entratlon and o~1 the pH scale has a value of 7 which represents neutrafrty. . This figure Indicates the concentration of hydrogen ions In a litre of solution and tor pure water the concentration for both ~rpes of ions being equal·at 1077
gram molecules per litre.
9
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SECTION A ==~~~~------------------~-·-------------------· Hot and Cold Water Supplies
WATER QUALITY 1
The pH value usually being expressed as pH ~ log -. H+
where H+ is the hydrogen ion concentration, hence . 1
·the pH of pure water IS log10 - = 7 10-7
WaJer having a hyd'!J9erl ion concentrallon in e~ of 10-7
gram molecules per iltre Will have a pH of less than 7 and will therefore tend to acidity !and conversely, watem with a pH of greaier than 7 will tend to idkalinity. From the above ~followS that pure water having no fi'9EJ ions has poor CQnductivily aoo high resistence to electrical culnmt. The conductivity, or ~ roclprocal resistivity, of a sample of 1water is a gOOd measure of its purity Where this is concemed with dissolved ionisable solids or gasas, which Is l"'ll"IY the case in resean:h end laboretol)' applications ..
Deionised Water \iVhere water Is required Icc a higher biological and chemical purity· than that supplied by the local water Authority, single or mixed bed deionlseiS are capable of producing pure and ultra pure water approaching theoretical Jtl20. _Purity is usually measured by a conductivity monttor which measures the conductivity In microsiemens. ·
The operation of deionisat~oo is bascid on Using twin bed or riiixed bed columns.of positive a:ncl negative charged ionised resins so that the incoming water dlii&SSOCiales into positively charged ioos such as magnesium and calcium which exchange. with the hydrogen loos <if the acidic resins. Ukswlse, the negative io'ns of sulphate and bicarbonates are exchanged wtth the hydi'Oxyl ioos of the alkaline 1'99ins, the resultant hydrogen end: hydroxyl ions combining to form theoretical H20. The exhausted resins are periodically replaced or regenerated with acid end alkaline regenerates. /'s the name of the procesS Implies, onlylonlsable dissolved solids and gases con be ren1oved and the treated water Is no1
· necessarily pura or sterile.1!Centralised recirculating s-jStems, boa\
units, and both in com :»nation where terminal poflshing is requited, can produce water up to 18 megohms at 250Cwhich is close to theoretical maxirrium.
F!Qure A4 shows a two bed rocin:ulation system suttable tor
Figure M llllclroulaiiiM doionJatloll syotsm
10
Lo· -to. service
Rng main return
1. Hand- wive 2. Break tank lor lliW water 3. l.<M' leYet noa1 soitch 4. Deliwiy pump 5. Pump motor startar
20
5
~ ''
12
6. Non mum valw 7. l'ooSSIIr"'llefval;o 8. lllt1ifj<lllng wat« meter". 9. Rat> of""' meter
10. 1Wo bod automalic delonlser
providir!l;l 3 M31HR of deionlsed water up to microsiemen cantirrn~re quality. lnstellaii<lrls should comply with local Water Authority requiremeniS to prevent backflow oootaminatlon.
Softe,ned Water Water Sl>ftening in large quantities tor commercial use end distribution Is usually carried out using one or more ol the lime or limelsodi! processes For domestic application hoNever, the base exchange system o1 softening is more commonly used and only this method lsdescriled. Base exohangesoltenlng operates on a similarpuincipleto the ion exchange described in Oelonlsed Water end functions by the process of axchanging sodium salts lor those of calcium.
The action ol softening can be expressed chemically as follows:
SOOIUM CALCIUM CALCIUM soDIUM
+ eldlanges to + ZEOLilE !'ARBONME ZEOLITE !'ARBONAfE
and that of re-generation:
CALCIUM SODIUM SODIUM CALCIUM
+ ~to + ZEOliTE· GHUJAIDE · ZEOLITE GHI.OAIDE
Because1 the base eD(Change system produces water of zero hardneS!~. it is allen only necessary to soften partofthetatal water requirement and blend the rew_and softened water togetha'
Operation of a Base Exchange Water Softener The raw/hard water supply Is connected into the to pol the softener tank end llows ·downwants uooer pressure through the bed of softenln{l mineral (zooltte) where the hardness Is removed by .the process t::lf 'ion EDO::hange'. At the same time, sediment In the water Is filtered out and retained by the minerel bed. Clear soft water. leaves tha bottom of the tank into the waler dlstr'.butlon sysiem.
· The softening mineral eventually beComes saturated with hartlnes:; and no longer softens the wale' Re-generation of the soltenin~l mineral Is then necessary and the three stege process is as follclWS:
10
Plant b'/·pass
9 a
11. SoilriOid """ 12. Brealillllk lor reciiCUiation \Wier 13: Reoi'ctCitlon pump 14. DeixllserC)inder· 15. lm•cell
•
2·
.1
Aaiv wal.er il
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(a) Backwash Reverse the wstar flow through the mioeml bed to remove accumulabad sediment and wash ID drain. A backwash controller is necessary to limH the waler flow and thus Jli8"<lnt washing out the mineral bed.
(b) Brine Rinse Ordinary salt {so<iium chloride) has the ability to lu!ly restore the softening capacity of the mineral. A measured amcunt of saJt. brine Is drawn from the brine tank through the brine injector and is rinsed slowly down through the minerai bed 1o namove the hardness which is rinsed to drain.
(c) Flushing The water flow is again reversed to ~ack the minerai bed end any trace of sediment not rBillCNed ill' the backwash Is flushed to drain. The softener can new be returned tc normal Mrvlce.
Distributed Loads on Steel Joists
w per Unit run= w K41
R,= ~ 1-----· .:.L ____ -+1 A,=~
(1) Bending mcment WL 8
(2) Bending moment • stress x section modulus =fxz
G·. Load distributed (kg) - 134.55 X zJm
c
~ ,, i\1.
L/
i.,!
libM AlB
Nominal Slll!(mm) iliH! Mass (kg/m)
203)<102
25.33kglm
78x102 ·
21.54kofm·
15~x89
17.61lkglm
1~x76
13.35kglm
102x&i
9.65i<g/m
71lx5_1
6.67Jq,~m -
0/stn!JutBd loads lor lpaDB up hJ 3 lllillrlo
Section Modulus
em' .,. 1.25 1.50
225.8
170.9
. 115.6 1tl370
74.94 IIOOl 6720
42.84 5764 ~1610 3640
21.67 2916 2330
-
SECTION A Hot and Cold Water Supplies
WL. Equating 8 = f X Z
and when f = 1S5N/mm
I = 1 metre
W = 8 >< 165 X Z m 1320.zlm m
13200 X Z Wkg • sa1 x m •• 13455.zim
Distributed loads In kg which c8n be carried ill' some Standard beams as RSJs are shown in Tables A 14 end A 15. ·
TlbleAU
Beam lqj/m Sodion modulus (z) mm em'
(1) 203 )( 102 25.33 225.8
(2) 178 X 102 21.54" 170.9
(3) 152x 89 17.69 115.6
(4) 127x 76 13.36 74.94
(5) 102 X 64 9.'i5 42.84
(6) 76x 51 6.trl 21.67
~bleA15
Calctl-s W(kofm) ' (1) 134.55 X 225.8 30381.39!
(2) 134.55 X 170.9 ~ 22994.59
(3) 134.55 X 115.6 15553.98
{4) 134.55 X 74.94 10083.10
(5) 134.55 X 42.64 5764.00
(S) 134.55 X 21.67 2915.69
Refer to Table A16 for loads at cl~ar spans, 1-3 metres:
Distributed Loads In Kllogrammes Clear Spans in Metres
1.75 2.0 2.25 2.50 2.75 3.00
15190 13500 )2150 11050 10130
11470 10197 9180 8340 7650.
8890 7780 6910 6225
5760 . 5040
11
SECTION A ==~~~~~~--~--~~~--·---------------------Hot and Cold Water Supplies
. .. · ..
WATER QUALITY
The nominal sizes of pipes and fittings used for ~ot and cold water installations in buildings are noomally decided on the baels ol two main criteria: (a) that the resistance o1 the pipeworl< Is loW enough to give the required outflow at the various draw-offs within the pressure head available. ·
(b) thstlheflow116locities:arek&pllow enough to~nsure, as far as is possible, that the system does not generate excessive noise whan the appliances are being supplied with water.
Anolher factor, which in special cases, must be borne in mind is the elf9c:t of erosion (due io cavilalion) and corrosion In pipeworl< whether external or interrial.
Expe~ments carried out at BRE some }'OS1S ago Indicated that acceptable noise levels Would be when flow velocities reached about 3mls.
The noise which arose when water was trilvelllng along the pipeworl< was affected, to some a>rtent, by the plpeworl< configuration; i.e. whethe'r sharp pattern elbows were· used or large ~dius bends. It would appear from the BRE expertments that the time taken for the sound 19\/el to be reduced to acceptsble ""'els was affecled by the melhpd of pipe fixing and the degree of absorbence olthe wall surface finish.
Very high water velocities creaie noise when c:avitatlon Is occurring, g<111erally at abrupt changes of direction. Cavilation is a cond~lon artslng whi>n pockets of vapour in the water suddenly collapse and the in-rush ~of pressure causes a distinct noise to emanate from the pipewcirk. Cavitation is also well· known to hydraulic engineers as a destructive agent which c'auses severe erosion and pitting of the material in contact whh Wi!t&r where cavitation is occuning. · n would appear ihat llmliing the water ve!ooities to about. 3miS, placing the plpeworl< on brackets which kaep the pipewor1< out o1 contact witr"l the wall surfa'ce and using sound absorbent finishes to the wall surfaces whorever possible are Important design considerations. A srnoot11 waterway through even small elbows also reduces substantiallY the degree ol noise created at these sharp changes of direction.
OUTWARD TIIRUST IN PIPELINES DUE TO INTEfllNAL PRESSURE
When water under pressure flews round any form ol bend there is an outward thrust at the bt,ond. Theloroewhich exists Is crealed by the static int~mal pressure and the dynamic force. created by· a change in direction of 1he flowing waler. For most nonnal vetocilles as used In water supply the dynamic force Is small and can be 1disregarded. All pipelines subject to Internal pressure must therefore be provided with ffnn anchorage at any change of direction and be restrained from movement at any blanked off ends.
The thru!~ P Is given by u,e basic expression
P ~ p.A.2 Sin ~
whare
P ihrust (Newtons) p Internal pressure (bar) = 10' N/m2
A .. <'ross sectional area of pipe (m') 6 " ••ngle of bend (degrees)
For ready applicatioo to most practical problems the basic expression given can be simplified down to:
p •• ;B.to-2.K.d'(mm)
where
K (90°) 1.42 K (45°) 0.765 K (22'12°) ·0.390 .K(11Y.o 0
) = 0.100 K (blank end) = 1.00
.Example Estimate the thrust which w~l be transmittecl1o an anchor block restralnttl!a 90" bend Uthebore olthe pipeline is 100mm and the lnt~rnaJ water pressure is 1 bar ..
p = 8.1o-2 X 1.42 l< 100" =8:< 1.42x 10'
P = t136 Newtons z 1.t36kN
The ou~vard thrust for various bores and angle of bend at a pressure of 1 bar can be read from Graph 1>5 based on the simplified formula. For higher pressures, multiply by the system pressure In bars. Where terSt pressures are in excess of system worl<inQ preSsures the greatest pressure must be used in the calculation.
Value~; of K for Various Bends 90"
2 Sin ~ = 2 x Sin 45° = K- 2 x 0.7071 ~ 1.414 = 1.42
45• 450
2 Sin --2- =- 2 x Sin 22Y2° = K = 2 >c 0.3827 >= 0.7854
22Vz0
2 Sin --2- = 2"x Sin 11Y•0 = K = 2 x 0.1951 = Q3902
11V4° . . . 2Sin --2-·-= 2 x Sm 5Vs0 -= K·2x ~5-=0.180
K = (Blank End) = t.O
----------------~--------·-------------------t2
· Copyright by the IP, Wed Aug 22 12:55:15 2001 ·
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SECTION A Hot and Cold Water Supplies
Graph A5 &tomll thrusts develop«J In plpe/IJIB$
350
25
- I / v !/ I ! . I ]I II --- il 17 v / II l/ / v
0 v ]I I
300
ti" I / / ~ il 0 ·-
I ~;;~f v )7 / t/ / ' I / ..
' ' II I i ; '/ ,I 0 !
/I ¢( kv / I ! I
/:/ ~ I I [/ ~~
00
/ I/ ll v L IL /' I
f.- --80 1.., II / i// . I ]I ..
ll / / v v 601/ / I i
·- 1-
50 !Ill // v I. I i
50 100 sop 1000 5000 10.000 2.10'
Thrusts In Newtons - (lnternal1 bar}
The size and shape of thrust bkx:l<s (concrete} will be determined bv the load bearing capacity of the ground where the thrust takes place. The following lnformallon Is given es a guide, but on- site checks should· be made, and if nacessary, an analysis of the ground condition should be.oblained. ·
Jllbls A17 BMdng capaclly Ill 11lf11
SoH type
Soft clay
Sand
Sandstone and QraVet
Sand and graver ~ended with clay
Shale
Safe liearing ~ad kNfm
24
48
72
240
Pipes should be run so that air is expelled through iennlnal fittings; balrvatves and space heating elements or vent pipe connections. Pipes must be suppo~ed to pllM!I)tsagging and the formation of 'iiigh polnls which will collect al[ This Is particularly impo~t 1or plpework where the circulation Is by gravity. Pipes should be fitied clear of tln.>ber joists, floorboanls and all building componenls. Where this;, not posslble, pads rasislant to damage by insects and vermin-should be fitied between the pipe and structure to minimise noise. ' · _
Protective saddles to prevent d"Jl1age by nails when laying floor boards and carpets should be inst!llled around &!I pipes located in positions where they might be subject to damsge.
Acoustic The plpework should be installed and secured In such a manner whCh will prevent contact with eleCtric cables. Plpework should not be buried in solid concrete. Where unavoidable, only short lengths of Jiipe should be Installed in solid concrete-floors or in walls without using dLJCts or Chases. Then, the
ACOUC'T'II'l A ••o pipes must be. installed to comply wtth Water Byelaws and British QIICI II, Standard Codes. of Practice.
· VIBRATION CONTROL. The minimum acceptable requirements for pipes installed ·with 1
solid and concrete floors are:
All pipes should bo securely fixed to rigid structures lidher than to (1} The pipe must be In a continUCIUS length without jointS aion9 lightweight flexible panels. When pipes are rigidly fixed to flexlblo the whole length of the embedded: pipe. structures wtth expansion joints, the pipe must be provided with (2} The pipea must be adequately p-.:ted from damage and movement joints. To reduce plumbing noises to a minimum, the· corrosion oy a specifically designed and manufactured piSsticS pipes should be irislalled in subslaotial and reasonably airtight cavarlngorbeprodu.ctsspeciflcallymanufactured1orthepu~• . ducts or enclosures, and adequately supported clear of the · e-
encloslng Wails. The pipes should never touch the st1-ucture. (3) The pipe must be edeqUaiely thermally insulated to meet the
-----~~--~~;~~~~~ 13
Copyright by the IP, Wed Aug 22 12:55:15 2001
SECTION A Hot and Cold Water Supplies
ACOUSTIC AND . VIBRATION Ci(JNTROL
requlremel11s of Water Byelaws and British Standard Codes of Practice. (4) The pipe must be frE!<l to mOYe along ils entire embedded length to allow thermal movementwtthoutdamageto ltsellorother
. members or property and must not cause, create, emrt or transmit · an audible noise. (5) Pipes passing through brickwork, masonary, concr8te, or other building componenls must not be 'built-in' but be provided with a neatly drilled hole or sleeve of suitable diameter and material. (6) Pipe fixings and supports must be fined at Intervals n01 exceeding 1.8 metres and where the pipes are fixed to skirtings or in othenulnerable posttions, the int81Val must not exceed 1.2 metres. All pipes should be supported to allow free movement for expansion and contraction. The support brackets should be of the screw fixing type with the prtlllision of suitable plugs for masonary locations.
Water Flow Noise Noise from pipework is g~nerally caused when th_e pipe su'!Bc~ are set into vibration ancUor oscillation by "the action o1 the water Hewing throoght the syst?m. water flow noises do not become significant below a watervetoclty of 3mk!. Cavitation will greatly imfrease noise. Although Cavita11on can occur in outlet fittings, it is not common in pipework because ~~ normal pressures, an average velocity of 7m/s to Bm/s is needed to produce cavltation In an elbow fining. Reduced pressures at the upper parts of water sySt~ms incorporating long drop pipes can causa cavitation to begin'
1et lower How rates and such pipework
should be avoided if possible. It Is essential that cavttation is prevented for noise revers: to be kept within acceptable limits.
Water Terminal fittings The sudden changes of direction and minimal downstream
. pressures that occur at the1seating of an outlstfittlng, such as a tap orfloat operated vatve,·cml create cavitation. This phenomenon is the major cause of nois~ in such fittings, whicH are the main sources of flow noise In water systems. Gavltation can be reduced by lowering the pressure at the point of inception and by reducing the water velocity. In termfnal fittings, the pressure at the point of caVita~on may be Increased by restricting the outlet . Tho water velocity al the ""ating, the usual location of cavnation Inception, may be neduced by design changes or by lowering the supply pressure. When suit:h a pressure reductiOn resufts in a tap being opened further to m!llntain the rate of flow, the water velocity through the seating!v.ias~er clearance will be further reduced allowing tho tap to operate mqre quielly. Similarty, a float operated
. valve will operate more qui1BIIy at a lcwe·r supply pressure, with the delivery rate maintained bY fitting a larger diameter seat.
Water Hammer (Impulsive noise) Stopvalve Operation When a tap or valve is cloeed lllpidly, the operation is S<lmetimes accompanied by a backing noise like that of a hammer blow. Possible prevention and alleviation of 'water hammer' may be achieved by preventing the sudden closing of the valves, by absorbing the pressure peeks; by increasing the attenuation of pressure waves when transmitted through the plpeworf<; by designing the pipeworf< to B'IOid long straight pipe runs and by restricting the water velocities.
Solenoid-operated valves and·se~.alosing taps are frequent!¥ the .. cause of 'water hammer' •noise. When fittings of this type are sp~fied, non-concussive, types should be used and property
14
maintained to ensure continuance of their non.aoncusslve qualitiea. An air vessel may be used to absorb the pressure wave at a point close or adjacent to ils fonnation. It may be> possible to reduce lhe pressure peak wave as it travels ·along th<> pipe. One solution Is a bellows.type vibration ISOlator to reduce pressure peak waves. another and more elfective being a rubber hcJSe.type isolator. By analogy w~h the sound transmission snuation, the use of 'plastic' pipes may be expected to prtlllide increased attenuation of the pressure pulse but with some materiallii, mcposure to excessiVe pressure surges should be avoided. Reference to British Standard CP312: Pert 2 gives guidancE• regarding the pennlssible limits ol pressure surges in unplasticized PVC plpework. The sizing of system pipework to limft water velocities to a maxlmurn of 3m/swill not· necessarily prevent the ocourrence of 'water hammer' but will be helpful in limiting the magnnude of the pressure peek waves produced.
Float Operated Valve Oscillation In the oVE>nt of an operating ann and float of a float operated valve being SE>t intO oscillation, the consequent rapidly repeated ·dpeni"'lllnd closing of the valve usually causes a loud and violent noise in the system which can shear the operating arm. There are many ~rMISOns for this oscillation, the most common being the' folmatlon of waves on the walar surface In the water storage cistemttank. This wave system is maintained by the intermittent entry of water through the float operated wive. Because of the extended duration of the 'water hammer' noise caused in this way, compared with that o1 hammer noise resuHing from vaJve closure, tt constitutes a very serious risk of damage to pipework and fittings should this oscillation Continue. When thl! float operated valve is correctly, in~alled, maintained, and Is sultableforthesupply pressure, the prevention of oscillation is obtained by Installing a damping plate immersed in the water of the storatiB cistern/tank in such a position as w!IJ give the greatest resistanC1! to vertical motion. This plate should easily be fitted to the fl0a1 ()f' arm. · An attematlve solution is to fil baffle Plates In the water storage . cistern/tank to Prevent the surface waves affecting the float.
. Surface waves can also be magnified when the length of the cistern tank Is In sympathy with the wave length end this can be eliminated by fixing baffle plates across the width of the storage structure.
Tap WElsher Olicillation (Valve bounce) RenewinH the washer normally cures the problem bui In obstinate cases, ~~ c:hange of washer matertal may be necessary. For float operated valves, proper maintenance of tho tap mechanism will reduC!! lhe tendency to oscillate (valve bounce).
Pump• Noise A correctly designed pumping system uaed under the correct condttlonu should not generate excessive noise. When the flow is much greater than the rated flovi or the static pressure on the pump is Insufficient, there is a risk of cavitation and turbulence, which could resuh In noise and vibration.
Noise transmission from pumps and pumping se1s can be reduced by using rubber vibration iS<llators between the pump and the main pipework. Suitable isolatOrs can restriCt transmissiOn of weter.OOnte noise and vibration of the pipes. The pipeworf< should be isolate;j from the building structure by using resilient Inserts In the pipe brackets. In severe cases of noise transmission. a hydr8ulil:.acoustic filter, tuned to the unwanted frequency, should be used and at this point the advice of a specialist acoustic englfle_er should be obtained.
Copyright by the IP, Wed Aug 22 12:55:1.6 2001
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Acoustic liansmisslon In practice, the transmission process from lhe noise source lo lhe hearer is complex ln110lvlng muttlpletmnsmlsslon paihs, including possible direct airborne transmission; transmission thrqugh the plpework; transmission through the building structure and possible various combinations. To minimize audible noise from fmlngs ~is neceS$8ry 10 lake all possible lmnsmisslon paths inlo considl:fraUon. Sound Is transmil1ad along metal pipes with lillie loss, and outlet filling noise can be mistakenly diagnosed as pipe flow noise. Plastics pipes attenvate noise. appreciably. The reduction Js not linear proportionally to the pipe length. BS 6700 gives lengths between Sm and 20m generating the mnge t Odb/n1 lo 2.5dblm, depending o~ the pipe material and walllhickness, and states lhat insertion of the metal-beUows type of vibration isolator in a metal pipe run can reduce the noise transmission by Sdb to 15db, but a reinforced rubber hose type of vibration isolator can usually give better attenuation values. Structure-borne noise should be reduced al source. The weight of the structure an'd the stiffness of the pipe ar:e major lactom In eliminating the noise. A t5mm diameter copper pipe llm1ly fiXed 1o a 230mm thick solid brick wall will not induce any appreciable vibrations in it . while a 25mm diameter nominal bore gafvanised steel pipe due to ·Its stiffer structure, can generate vibration and so transmit. noise. Lightweight stnJcllures are relatively easy to set into vibration and readily transmit structure. borne noise. When pipes haw to be seournd to lighlwelghl
. SECTION A Hot and Cold Water Supplies
Impact Noise in Sanitary fittings Taps can generate noise by the impact ollhe discharging water stream wfth the surlaces ollhe sanilaiY fitting appliance. The use · of floW aeralom is helpful in rnducing such· noise as lhe most disturbance from this type of noise can occur whh mstal sinks and similar appliances. The undamide of stainless steel bowls and draining boards
. complyingwnh BS;t244 m~ be treated lo minill]izsyibr.jllonand noise transmission. This treatment could be applied lo oihertypee of llghlweighl appliance when wale~ Impact noise is a problem,
.. and. in some ir}Stances, additional t.reatment of stainless stEM;~I appliances could be worthwhile. n is good praclice 1o isolate lighlwelghl appliances from lightweighl !'ructuml elements.
Thermal Movement Noise· Noise caused by the thermal movement of pipes can be disturbing by generating creaks, squeaks am:( banging noi~ which can occur after the water has been dmwn off. Slgnlllcanl thermal movement occurs In hot water pipeS as a result of temperature changes. Expanding pipes when inStalled correctly Wnh proper expansion allowances do not creata noise. The use· of resilient pipe clips or brackels, or resilient pad.s belween pipes and fixings, win, In many cases, Introduce sufficient flexibility lo lake up thermal movements. Where very long Sllaighl runs of pipe are I!Mlivad, expansion loops or joints mi!Y be needed. In such cases. refer to·pipe thrust section of this Guk:le.
' structures, lhe use of flexible and vlbrallon-isolallng clips or Aeration of Water Pipes brackets are required. Where a design choice exists,.,the use of . 1 smalldlametercopperorplaslicsralherlhansteelplpes·shouldbe · Bubblesirrlhewatercancauseaslgnllloanl ncreaseinwalerflow
sfe noise which normally cx::curs in the .hot water system and arises used to reducelhelran r of sound energy from fl1e plpework to from poor design or operation of.lhe !;'Stem. Bubbles fonming In or the structure. I . . passing into water heaters of hot w~itter cylinders are particularly Where noise Is likely to be·transmitted to large surtaces such as noisy. Domestic hot water systenls must be desJgned. al1d · storage cisterns and tanks which rest directly on ceiling joists, operated so as to avoid generaJ and/or localized boinng, with the thereby giving a direct acoustic coupling wllh the air in lhe · whole !;'Stem being designed to fa~llltale removal of air during habitable rooms, Isolation of lhe structure from lhe plumbing filling of the !;'Stem after maintenance. component is essential. Resill~nt mountings can be helpful in Isolating a water Slorage cistern/tank from tts supporting structure · Acoustic Bridge and the advice of the manufacturer of the mOuntings should be sought to ensure the correct type are selected for the specific In addition, noise generated by the water service installation may application. intr:oduce problems by acting as .a noise transmission. path
bridging structural sound insulation~ For sensitive habitat areas Flow noise originating In outlet fittings and transmitting to the pipe such as recording studios, the insertion of flexible vitiration runs can be reduced by running lhe pipes In closed duets when isclatOJB in pipe runs may be necessary and should provide the soond radiation from the pipework Is a polenlial problem. · desired degree of acoustic Isolation.
Float Operated Valve Water Noise When the stream of water Issuing from a f1oal opernrtad valve Strikes the water surface In the water storage cistemltnnk or the cistern/tank itself, the resufting noise can causa ; serious dlslurbence lo lhe occupants of lhe building. Previously ft was common practice to supty water from a float operated vatve at a level belOW' the normal water surface by attaching a 'silencing tube' to the valve outlet. Due to difficulty in rneetlng the backsiphonage protection requirements of BS 1212 when silencing tubes are fitted, this practice is no longer used. Backsiphonage protection Is usually achieved by the float operated valve discharging above lhe surlace of the water in the water storage cistern/tank with silencers available for some types of BS 12'12 valves. These reduce flow noise generation at the seat and. alsc control lhe emergent water stream 1o rndw:e splash n01se.
AOal operated valves using collapsible silencer rubes in conjunction with built-In anti""'aCuum devices are available and are listed by the Uniled Kingdom Water Research Centre (WRc) Fittings Scheme which comply 1o the byelaws but do not comply with ·es t212. The isolation at Slorage cisterns from the building structure is essential" and this is necessary to reduce noises caused by splashing.
WATER.HAMMER Water hammer is a pulsating type of noise which may, on occasion, be heard emanating from a pipework installation. The noise Is caused mainly by shock waves which are sal up when water. which Is flowing at high velocily, is suddenly arresled .. The practical condnlons which can create lhls adveiBB effect are the too rapid closure of manual valves, or the virtual instantaneous closure of automatic control valves.
Pumped piped water s4ppf105 are also liable lo water hammer If· provision is not made at lhe design stage. Plunger type pumps tor example give a pulsating type at discharge which may require dampingout. .
Cases have occumed of water hammer damage although little audible scund was present. Premature failure of valves, joints and the loosening oi supports and clips aie common exar,nples of such
·damage, . 1
Gravity water Installations Po not as a rule give rise to the problem
----~---------------------------------15
~Copyright by the IP, Wed Aug 22 12:55:16 2001 ,. ,' ' '
SECTION A Hot and Cold Water Supplies
WATER HAMMER but wMn waler"velocltles :.Xceed 3m/s, water hammer condttions may exist. The increasing_ use of pressurized domestic water systems In the UK could well lead to a'n Increase in the incidence of water hammer !I proper precautions are not taken a! the design stage.
System Protection Sheck pressures In piPB")''rk supplied at high pressure can be reduced to acceptable liinits by lncorpoJaling hydro-pneumatic accumulators or water hammer anestors In the pipeline at suitable points. The ea~iest form of water hammer absorber was the simple air vessei or air bottle. In service, these usually became water-logged arid Ineffective unless means were available to renew the air cushion. Modem hydro-pneumatic accumulators Incorporate a precharged flexiple gas bag in their design which is filled with air or nftrogen gas(see Figure As). Lossofalrorgas in service is thereby prevented. Consequently; their continuing efficiency in service is satisfactory and reliable. When used for this application, hydro-pneumatic accumulators absorb the kinetic energy of the moving water and much of the initial shock pressure; this oocuring when the nitrogen gas is compressed in the flexible bag.
Basic Design Principles The shook pressure waves which may be generated In pipes, travel al a velocfty V which is affe<:ted both bv the comprosslbilfty of the water and the elasticity of the pipe walls. It can be shown mathenialicallythatthe velocftyofthe shockwave Is close to 1he velocity of $ound under the ~arne conditions.
The time interval, in seconds, for a shock pressure wave to fOITTI at the back of a valve or oth•" arrest point Is given by:
t = :!x length of pipe" va'.ccjty of sound
t = 2 x"L v,-
l'rote<tlve C8j) protects llf'<l\arge YIWe against domaoe and dirt.
Sch""" type non-retum YIWe backo<l "' will\ ·o· rinll sea1"" 10011> saalnJI.
'JU~~~ Naml!lllatB, colour coded IJr different "''0no
pressUres. · ••
Sl>ei slrell. No lml1S. - or PJinls. lk7,<1s ilpproo.od and Ill Home Office spocification 'S'.
~--11'1- Separalrx bag, f1jy or- and aYailabla In a \OIIety rlnt;il!rlals (til<! bag ~ quickly r>placeable). The shells treated Ill PIMnl corrosion. Poppet vatvo. spri~ed p18Yerrts bag P.xtruslon. l~lllld m. !of quick and controlled ll!mtNai of ill- or 11uid. l1uid pofl; maximum possiJie flow ''" alaMng 1.11gt1 flow r.rta Easiy "'"""""'for bag Ill placement.
The vaiO<:Ity of sound is 1450nils under perlact conditions. In the case o~ 1;hock pressure waves, this is usUally reduced by the conditioons prevailing which must be taken into account.
·Example Calcula!EI the time required for a shock wa"e to fonm at a rapid closing v.atve in a pipe 14.5 metres long.
V ~ 1450m/s
t ~ .2L 1-150
t. 2x14.5 1450
t = ~ seconds
Solenoid wives of the type frequently filled to automatic washing mach in~~ etc, have closure times Of a few milliseconds i.e, 511000 or 2/200 t;econds. This type of vatve can therefore be regarded as tap:id ~ling and liable, In some circumstances, to cause shook waves to be sat up when In operation, p~lcularly when they are installed in high pressure water ln.'llallations. It can be ''hewn that, If the time taken to close a valve Is less than that ,for the pressure wave to travel the 1en9th of the pipe, the pressure wave produced Is equal to that if tile valve was closed instantafli:JOUS!y.
Shock Pressure Rise '#hen considering water hammer problems, lt is necessary to take into account the initial water velocities, the pipe material and the disposition of the pipe runs.
ape,.til311J . . T.he accuroulator Is fi..t charged with nitrogen at a prodetennlned P"""'""'· !Auld from the pump enters through the Huld port, compreosing the gas In the rubber bag, the bag 11oeling ""'-n gas and fluid in equlllbrlum. TM gas rnaliltalns pressure In ltlo accumu1at.or and forcM out the syst&m flued under pressure when the 1::ircu1t mqulres it.
1. Accunl!iilllr neillleriQ$SIX/gtd""' c:lwped 2. Acam!dator,..._with fPS. a Gas ., 1>111 """fli8SS8d bt #uld trom pump. 4. Big.,.,...,. aner ~ w.
' ' •
------------------------------·------~------------16
Copyright lby the IP, Wed Aug·22 12:55:16 2001
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Giaph M shows that the velpcif¥ oi the sound wave is affected by __ . the nialn conditions: · .
(Q The pi~ material, I.e. value of 'E'. Qi) The dlamatsJtwall thickness ralio. (iii) The bulk modulus of water oJ 'K'. These variables are taken Into account In the basic formula below:
v~ = / P(k ~ ~~) where: V = velocity of sound pressure waws (m/s) p' = density of water in (kg/m') K = bulk modulus of water = 2.()7 GNim' E = modulus of elasliclty of the pipe material
E =lor steel= 200GN/m2
E = for cast lron -= 100 GN/m2
E =for copper= 110GN/m2
~ = pipe diameter/wall thickness ratio Qndependent of. the t units) . . .
Graph M is based on the above formula Theshockpressurerise In a pipe can be shown to be given by the product of the initial water ve~ity and the sound pressure wave velocity from which:
.Pr=V5 .V.kN/m2
where V = initial water velocity in mls P, =pressure rise kN/~2
Example 1 Galct!late the shock pressure rise when water Is flowing through a 150mm nominal bore copper pipe at 3 mJs when the water is suddenly arrested by the closure of a valve.
For 150 mm pipe -~ a 80 (see Graph N!J)
From Graph N!J V, ~ 92Sm/s.V = 3m/s
· Pressure rise Pr = 925x3 P a 2775kNhn2
~xample2 Gaiculate the shock pressure rise when water is flowing throogh a 15mm nominal bore copper pipe at 3mls when the water is suddenly arre!'led by the clooure of a valve.
For 15mm pipe ·~ = 2011) (see Graph A6)
From Graph A6 V, = 122Smls.V £ 3m/s
P, = 122S"x 3 P = 3675kNim2
It will be seen from these· twO examples that thinner wall pip"!' reduce the pressure rise more than rigid thick wall pipes.
Sizing qf Hydro-Pneumatic Accumt:ilators In addition to the shock pressure rise, the plumbing dEJSignermust also calculate or otherwise evaluate, the kinetic ener'gy released by the moving water when it is brought to rest. In a hydro-pneumatic accumulaiOr, the ldnetlc energy Is absorbed in doing work by. compressing nitrogen gas.
Hot and Cold Wate
kinetic en9f911 destroyed = work done on gas In .. on imp"act ' ai::cumulatOr
~"' p V2-P3V3 =INOrkdone I<E=:z112mv-- 2' n-f
where:
forKE m=masskg g = 9.81 mJs2 v = Velocity m1s
Example 3
work done on gas P1 =gas charge pressure v ~ = gas charge volume .P2 = Initial pre5sure V2 = innial gas volume due to P2 P3 =shock pressure V3 =shock volume n = 1.4 (gas index lor nitrogen) p ~Nim'
V =cm2
Water Is flowing at 3m/s through a, 15mm nominal bore (13.6mm aclual) plpe when the water is suddenly arrested by the closing of a v.>lve. Calculate the KE of the moving mass of water If the pipe
. is 15m long.
KE • V2m V" mass of water moving at 3mts
-rdz L mass • 1000 x 4 x 10'
15 = 0.7854 X 13.6" X 10' .
mass a 2.18 kg
I(E = 1/2 X 2.18 X 32
I<E • 9.8Nm
To provide a small working margln·to allow 1or variations In actual pipe bores say KE = 10Nm.
f:~ote (i) If the pipe lengrh remains constant then,
new KE = original KE x (~)'
(il) If the pipe lsngth is altered lhsn,
new KE ~ original KE x t. E.xample4 Calculate the volume ot nltiOg.., 9as In cm3 required to be pi"OIIided in a hydro-pneumatic accumulator which Is required 10 absorb the kinetic enellJ)'ofwalerwhlch is flowing at3m/s through" a 15mm diameter pipe 15m long. The line pressure Is 414kN/m2
and the shock prassuie rise Is not to exceed a funher kNim'.
Note Initial fill pressure of the gas is to be 90% of line /XSSSlJre. Absolute pressuros have been obtalnsd by adding 100kN!m' to gauge pressures.
------------------------------------------~-17
Copyright by the IP, Wed Aug 22 12:55:17 2001
SECTION A Hot and Cold Water Supplies
WATER HAMMER Figure A& .Accumulator sizing
.--r----. --.-. jv,
V, P3 =524+720~1244kNini' . " ··.
(Q Initial compression= PT~1 = p~~2
(ii) CompreSsion duB to shoCk Pressu'ras = ·P;.~ = P3.~ (iii) Work done on gas= P,V,- P,V,
n-1
Allowing for initial compression due to line pressure, and assuming T 1 • T 2 (constant temperature)
. P, P1V1 = P2.V2 or V2 = p
2 V,
470 . =
524· X 100
v2 w 90cm3
Taking n = 1.4 (nitrogen)
Main compression due to· shock pressure
P;.V';= P, V';
v3 = v2{=:} ~ - (~)'·"· -90x 1244
90 -~
90 = 1.854
Va = 48.0cm3
Work done on the nttrogen gas during compression stage
WD = P~V2 - P3V3
•
n-t
(524 X 90 - 1240 X 40.0) (1.4-1) 10'
(5.24 X 9 - 12.4 X 4.80) 0.4
47.2-59.5 0.4
. 12.3 = - 0.4
WD ~ · - 30.6Nm por 100cm'
from Example 3, KE for ism run of 15mm pipe, v = 3mls
KE = 10Nm
Volume of nitrogen tor 10 Nm of energy
100 Volume = 1 o x
30_6
• 32.6cm3
Volume :=tay"" 33cm3
Example 3 can be used as a basis tor other condHions .
It will be Clbserved thatthreevariables can be Isolated as affecting the kinetic energy to be absorbed under any given practlcal conditions.
(i) KE "'n vary with the square of the diameter (d'). (IQ KE can vary with the square of the velocity (V'). Oii) KE "'" vary wtth the length of the bmnch.
From which we get the following relationships:"
(ij New KE = KE x ~: = KE x (~)'
(ii) New KE ~ KE x ~~:) ~ KE X~~) OiQ New KE = KE x 1.,
. . L,
These relationships have· been applied to obtain the volume of nitrogen !:Ja.S for other pipe diameters, velocities, pressures and lengths.
Hydro-Pneumatic Accumulator Sizing KE o11Mmm dla(15mm NB) copper pipewlien thevelocltyolthe water is3m/s and length of 15m. KE=10Nm
For 20rnrn NB 20.2mrn (actuaQ
KE= tOx ~~:~)' =222Nm
For 25mrn NB 26.2mm (actual)
KE = 10 x ~~:~)' = 37.0Nm
For32mrn NB 32.6mm (actuaij
KE1=10x (~~:r a57.5Nm
For 40mrn NB. 39.6mm (actuaQ
KE = 10 x (~::)' = 85.0Nm.
For 50nnon NB 51.6mm (actual)
KE = 11) x (~~::)' ~ 144.0Nm · .
~--------------------··----------------18
Copyright by the IP, Wed Aug 22 12:55:17 2001
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SECTION A ----------------~~~~~~~-~~~~~~~ Hot and Cold Water Supplies
TBbm,l18 Accumu/8/or sizing I
calculated 42m head v-am/s Volume POl Copper Klnetfc Volume USA/POl 42m Pipe Energy lOP
15 10.0 32.5 33 A
22 22.2 72.0 68 B
28 37.0 120.0 119 c 35 57.5 186.0 187 0
42 85.0 276.0 257 E
54 144.0 465.0 475 F
'filble AlB Accumu!JJhJr slzklg 2
Ca~ulated OOm head v= 3.5m/s USA Copper POl Pipe KEx15 Volume 60m
Head
15 15.0 48.6 B
22 33.2· 108.0 c 28 55.2. 180.0 0
35 86.0· 280.0 E
42 122.0 470.0 F
54 216.0 700.0 OF
78bl8 A20. Flow tales tmm copper lubes sl311!1!1snd equivalent 101' loading units
A ow lOP Olameter rate KENm loading USA POl mm lis units vol. silo
15 . 0.52 10.0 25 33 A
22 1.10 22.2 75 66 B
28 1.80 37,0 140 119 c 35 2.80 57.5 400 187 0
42 4.00 85.0 500 267 E
54 6.80 144_.0 900 475 F
f57 10.00 214.0 1600 800 OF
76 14.00 268.0 2500 900 FF
In the USA where hydro-pneumatic accumulators or water hammer arrestors are widely used on high pressure water installations, a method of rationalizing the capacities ot. the units has been .adopted.
Six 51l!ndard slzos frOm 15 mm to 54 mm are given oojeletters A to F. Size A, which Is Intended for v, in or 15mm pipes is the smallest (see Graph A7). For applications outside the largest standard siz~. various combinations of the six basic units can be used ($ee_ Grllj)h AB).
Note
The basic pipe length is 15m and the velocity at the water is up to 3mfs. The basic line pressure used Is 42m head and the shock pressure I MN!m' or 102m head. The adoption of a 31M; 1/mff an the velocfties ussd with the basic sizes also provides a rational basis for sizing the units In a .L-S raffng or in lOP loading units.
A table giving the anemative sizing is shCNm in 7!lblo A20:
Hydro-pneumatic accumulator sizing based on the kinetic energy of the watsrfloWing In the branch can be conveniently carried out by referring to the Graphs A7 and A8 For sizing units where the branches are oi variable lengths use Graph AS.
Example 5-Calculate the KEto be dissipated by a pumping main at tho point of switch-off and the resultant shock pressure rise. 1
Data 1 •
Static head 50m Pump power output 4 kW
"' d' Massofwater=px 4 tO' xL
Diameter of main 75 mm
. 762 ~ 1Q3 X 0.7854 X 1~ X 50
= 0.7854 x 7.62-x 5
Mass = 227kg Farce= m x a= 227 x 9.81 = 2220N
4kW = 4000N. mls . 4000Nm/s
Velocity atwater~ =oN = 1.8m/s
KE ~ 1f2. mV2 = 112 .227 x 1.82
KE=368Nm Pressure rise at switch off
d Far 75 rrlm steel pipe, 1 = 15
from the graph AS
V5 = 131J;m/s P, = V5 V = 1315 x 1.8 • 2370kN/m2
P, = 2.370M N/m2-= 2.37M. Pa
ExampleS A pump Is supplying overhead stor-age tanks with water under the following hydraUlic conditions: Static head 50 m Effaclive pipe length Including fitting resistance 150m Pipe diameter 50m
head 50 length = 150 ""0.33m permet~e run
From lOP pipe sizing chan, Graph At, a 54mm pipe ato.33m/m run will give a flow velocity of 4mJs
"' d' mass=p. 4 . 10'.L
,n' 0.7854 "' = v-x~ x5v-x125
= 10 X 0.7854 X 5" X t.25 =246kg
KE =-"hm.V2=~x246x42
KE ~1960Nm .
50mm pipe, ~ = 12 t .
from _graph A6 V5 = 1330m/s_ Pr ""V8 .VkN/m2
=1330x4 = 5320kN/m2
P;· = 5.32M Nim2 = 5.32M. Pa .
------------------~,-----------------~---------19
l Copyright by the IP, Wed Aug 22 _12:55:17 2001
I' I
SECTION A Hot and Cold Water Supplies
WATER HAMMER Exarople7. Calculate the capacitybf a hydro-pneumatic accumula!or required to be provided for a Sm branch pipe supplying tO wash basins concentrated use. Velocity of How 3m/s From TObie A2 tOwb-tOx3~3oLU
and from pipe sizing chart, Graph At . 30Lu = o.eolls .
From the pipe sizing chart Graph At, a t5mm· pipe wUI convey 0.61/s at 3m/s and from lhe selection chart for hydro-pneumatic accumulators, Table A18", a 15mm pipe canying water at 3mls requires a 1~cllfl accumulator. The nearest standard slz,e ls 33cm3 Or.PDI'A'. . . .
Exantple8 A branch pipe It m long, Is under a static head of 40m. The estimated flow rate is 3.21/s. From the lOP pipe sizing chart a 42mm pipe would be ~~~quirad for the branch. 3.2Vs is ·Bqulvalent to 350 LU. From tho hydro-pneumatic sizing graph Nl a 42mm diametl!r branch tt m tong would require an accumuiO!Or of 190cm' capacity. The nearest single size is 267cm' or PDJ size 'E'.
In practi"e twosmallerunitscoupled lntandam v.oold probsbiybe used.
From wt1ich 1;o = 95cm'
Nears<rt size to 95cm' Is 119cm'. Therefore two t19cm' accumulators could be used coupled PDI size 'c·. I
--------·-------------------u------------------. 20 I
Copyright by the IP, Wed Aug 22 12:55:17 2001
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1
p(~+~ Grnnh of the Jormule~ V.
120t----
110t----~-~~-r-----t----~------r------~----t-----+-----+-------r------i
100t-----~------~------+---~-----r-----+----+-----t-----4------t------i
! 00~-~-r--~-~-t------r-----+----~---+-----r-----+-----t---~~ li L· ' ~ ! ao'-"'-""'--+----1-------"~ ~ ~ I
lij:i! ~jro~~~--~~~---r-------r--~~-t--~---+-------+-------+~-----+-------+--------r-----~ E
~ 60r----T~-~~~--+---~~--+----+----t---~---4---~---1
~ 1 -sorl-·------4----
4ot---~r----t--~~~~~~-----+-~~+-----~~-----r-----t-----_,------1
30t-----~,------t----+----~~~~~~----+-~~~-----~----t------+-~---1
20t-----t-~-+-----+-~-+----+~~=-~~~~~~~~--~---~-----1
) 10~----+---+----+---+------+-----+----+~~~~~~~~~-~---~
0 --
~ B = - ~ 1& ~ ~ u· E - ~ Velocity of pressure waYe (m/s)
., iii . ~ 1J:
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L.-J ' '
•. SECTION A 'If Hot and Cold Water Supplies
v
Gniph AT HYJIIV"fl/llfl1118tlc KCUmuiaWr 8tllet:l/on chlllt ($Ingle uniiiJ
400 -
300
··.
200
\I:Jiurni ima=KE Nm)x 100 29.5Nm
15 0 x : ..
/ ' .. ...
0 /
/ 0 /_E
0
1/ 0
/_ 0
/ v
0
I . 7'
0
I v I /. i 0 /'
100
. 9
B
7
6
2
./ 5 v· I
I /' 0
~ 9
"
. 1
Bv ..
7 -
6
5 .. 25 30 40 60 60 100 150 200 300 400 500
Volume of nttroge_n in accumulator
~------------------------··------------·-------22
Copyright by the IP, Wed Aug 22 12:55:18 200l.
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SECTION A Hot and Cold Water Supplies
Graph A8 HydtrJopneumstk sccumula/or soJoclion cbBrl (muntple ooia)
1000 900
800 700
600
500
400
300
20 0
. 1 50
00 9!i 80
70
60
50
I
I
40 /
30i/c' 20
. 1 5 .
10. 100
I I
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/
150 200
, .. " ... I
KE(Nm x100 29l>~m i
v VF
/c F
/c /' \
.. ~ ... "
/ /E
-300 400 500 . 600
Volu~m~ of nlt~ge~. in .accumul~tqr
Copyright byrthe IP, Wed Aug 22 12:55:18 2001
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BOO 1000 1500 2000.
23
~ . ·~t:·
.. ff.'t~, SECTION A ~~ Hot and Cold Water Supplies
·~~
Urafl/1 A9 ffvrfrrrpneumatic ar;s;umufalor selection chalf (5-50m pipe run)
.100G,.-------,----;----·-~-.,-~~--:
goor---6CDI-- -------1-----+--
i
!>DOl----
400 1--:---.,.----,----''----
3Dor---
200 --··
i I . !
--------1
·------1
------------1
10_';-------~----~----~,.----l::-------.,.,...- --_,l ~s 22 2a 35 .;z f.: _
Dlame1er of pipe (copper)
24
Copyright by the IP, Wed .(\.ug 22 12:55:19 200:L
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T 1 ..
INSPECTION AND TESTING OF WATER MAINS AND WATER SUPPLY SYSTEMS
Water Mains The mains should be tested in sections as the work of k.ying proceeds and joinis should be left exposed for Inspection during testing. After completion of each section, tho main should be carefully and slowly charged wnh water so that all air is expelled, allowed to stand full of water for 1-2 days if possible and then tested under pressure. The test pressure should be 90m head or tho maximum working pressure ,pluS 50%, whichever is tho· greater. The pressure should be applied by means of a m•nuallyoperated test pump or, In the case of long mains or mains ar large diameter, by a power-drtwn test pump provided that the pump is not left une.ttended. Precaution must alwa)<S be taken to see that the test pressure Is not BJ<ceeded. Pressure gauges must be accurate and If necessary should be <&-calibrated before the test. After the PumP has been stopped, the test pressure should be' maintained as Jong as is necessary to Inspect the whole at the pipework under test and In any event not less thE1n half-an.hoUr.
Open ends of rnalns should be tempomrily closed for testing Uf1der moderate pressure by frHing watertight expanding plugs. The en·d of the .f11ain and any test plug must be well secured to resist the erid thrust of the water pressure in the main, i.e. maximum test pressure x crass sectional area of pipe. If the section of main terminates with a sluice valve, the wedge of the valve should never. be used to retain the water because this might lead to permanent distortion of the v.<>rldng parts of the valve. tnstea:d, the valve should be fitted with a blank flange or socket plug and the valve left in the open position whilst testing. End support should be provided as explained previously.
Cold Water Systems . When tho installations are complete they should be siO)Niy and carelully charged with water, allowing all air to escape thus avoiding shock or water hammer. Tho systems should ba Inspected under v.<>rking conditions of pressure and flow and when all draw-of! laPs am closed, should be absoltrtely watertight. · E;ach draw-off tap should be opened and tested tor raue of now. Certain specifying authorttles may requim pr8S5ure testing of internal pipework In which case, systems should be tested in accordance with the pressure test preVIously described. In such cases, it may be necessary to Isolate nems of equipment from the pressure test H they are not capable of withstanding the test pressure. Where these items are removed, blanking Ranges or plugs must be used or a make-up piece ot pipework Installed temporarily. . • ·
All ·piping, fillings and appliances should be Inspected and chocked for satisfactory support and protection from physical damage, corr~IOf'! and frost.
Because. of tho possibility of damage In transit, It Is always advisable tQ re-test cisterns, tanks ana cylinders tor watertightness on' arriVal at site an~ before fixing .
Hot Water Systems Hot ~ter systems should be ihoroughly flushed ou! and then tested 1n t~e same manner as described for cold water systerris. Whore thermal lnsul~lon is u&ed, tho hydraulic test should be .. made before the insulation work is completed and Whilst an joints · are exposed.
Where a pressu.re test is employed, boiler and calorlfier ·reuef valves should be removed and these valves should be tested tater. The test pressu1·e should be one and a half times the nonnal
SECTION A Hot and Cold Water Supplies
woridng pressure and this should be maintained for thirty minutes after makl~g good any leaks. It Is necessary to carry out the hydmulic pressure test on sec!lons of pipeworli prior to completion of'the whole lnslalletion where tqese ara.fl~ in duqls, ChaseS, trenches, etc, and are concealed from view. If rectification of faulty materials or workmanship on such sections is likely to involw disturbance to finished structural features, the test pressure should be twice the normal mr~ing pressure.
Sterilization of Cold Water Systems The whole of the system should be stertlized to eliminate possible traces of bacterta. Sterilization of public water mains. Is carried out by the Water Authority who may also carry out the stertlizatlon of new private mains. Where this is not standard practice, the plumbing contractor should cany out the sterilizing process as described below. After cleaning the cistern of all debris, the clstem and pipework should be filled with water and the whole thoroughly flushed out The system should then be filled with water a second time, but as the cistern is filling, a sterilizing chemical containing chlorine should be added to ensure thorough mixing of the chemical and water. The dose should be such as.to give 50 parts of chlorine to one mllrlon partsofwater.lfordlnarybleaching powder is used, the proportion should be 150g of powder to 1000 Jares of water, the PowtJer first being miXed with water to a creamy qonslstency before being added. Proprietary brands of sterilizing chemicals should be added in the proportions as Instructed by the manufacturers.
After filii rig the system, the Incoming water supply should be shutof! and each tap on the distributing pipes opened sucoassively, starting with that nearest the cistern. />s the water which issues . from each tap beglnstosmellofchlortno, the tap should be closed. The cistern should then be filled again to the water-line wnh water to·whlch has been added the correCt dose of chemical: · · The whole system should then be allowed to stand charged with treated water for a period of at leaSt 3 hours, after which a test should be made by smell for residual chlorine. If none is found, the sterilization should be repeated.
Before any water is used for domestic purposes, tho whole system must be emptle<(and thoroughly flushed out wnh C!earl water.
PREVENTION OF CONTAMINATION OF WA1IR BY BACKSIPHONAGE · OR CROSS CONNECTION
Water Byelaw requirements for P"*""lng mains supplied water services from tho risks of contaminalion arising from backslphonage, backflow orcross-connectlon are concerned with ' three principles of protection: ' ·
1. Water supplied from tho mains must be kept seperale from any· otherWalsr, such as that supplied from a private source (e.g .. a well or borehole) and Walsrthat isotheJWise non-potable. This includes mains supplied water that has been drawn-off for use even if Its quality has not deteriorated. '
2:· Thera must be no ·cross-cOnnectiori within a Water installatiori such as between mains-fed supply pipes and cistern-ted distributing pipes, and between cistern-fed primary and secondary hotWBlerclroul1s. Although a closed circun must not be connected to a mains-fed supply pipe, the primary heating circuit of a sealed system may be filled or topped up from a temporary
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. SECTION A Hot and Cold Water Supplies
PREVENTION OF CONTAMINATION OF WATER BY BACKSIPHONAGE OR CROSS CONNECTION
connection made to a. supply pipe, through an approYO<i and effective backfla.v prevention device, provided that the temporary connection Is removed after use. Tha connection of any pump or Other similar device into a supply pipe, so as to cause beckllow Into the pipe, is prohibited.
. 3. Every point of water U!SS, such as a draw;off tap, we flushing cistern or washing machine, must be protected against backflow by the use at a suitable backfla.v prevention device. . Requlremems for beckfla.v protection ateV19rypointof use of water are based upon tha recommendations of the 1974 Report of the COmmittee on Backsiphonage In Water Installation, for tha three calegories at risk shown· in Table A21, ruid illustrated In Figures A7-A12.
BACKFWW PREVENTION DEVICES The following protective devices are those considered acc8ptabie and mentioned in tha Model Water Byelaws, June 1986. As other Flgums A7-A12, EDmplos or blc/dlaw pmloclfon
26
Supplypipe
SUpplypipe
-- T)1>1> A air gap
----
Glsten)
Hazard to health, continuing or freqoont
-- --il'JYpe A air gap - -
.
From customer's IMrl
Cistern soon:e of non-potable wa!Br
Jipo B *gap, pipe irle~er, doWie check wl\o assembly or BS 1212 paris 2 or 3 float
0~-
Glstem !~m :oJmm
"'" to ... -Hazard to health. corrtlruflll or frequent
CategOI)' ol rlsl< source Eltamples of recommended protection
CIBssf R!sk of contamination WCpon ApprcM!KI flushing whieh ia Uks~1 to be ci!ilem coJT&CCiy harmful 110 health, from a ln&talled subst:anl:e ccnlinuously or """' T)1>1> A Bi<iJ'I' frequently pmsent
Cla8S2 Risk d contamination T"" a1 Type A air-gap whletl 1$, or U1 Uke!y olnlal etc to qe harmful to hea.tlh, Hoe~:t union . Combination in-lin&-from ti SUbstnnCe whlcti - vacuum and check VBMt. may be presont C~nshlng Type 8 air-gap.
mach!-
"C.S3 Aisle of cootaminat!on Hot & cold hrf of tho aboYe device8, which Is .not, or ls not mlxt;~rtape or a check valve or an llk&ly to 1,e, harmful in line anli-Yacuum valYB. to health Domestic Arry of the aboYe devices.
'no less Eflfectlve devices' are developed 8lld accepted, they will be lisled in the 'Water Fittings Directory' published twice-yearly by the Wate1· Byelaws Advisory Service of the Water Research Centre.
Su~~·-p\Je D
A
c B
Glstem ,,.,.,... 3 points of use A, B and c and prMrrts -• from all! ooe ~>acling lhe cistern fetd ~pe D. The~t~ Q)Uki be crnss-contarrinatlon IJetoM:en A to 8 or C and from B 1o C urioss !\and B iiso lr1co!por;te a~proprialll prutedloo at A arn1 B.
r--J,===='-liPe Bar gap,1 pipe lrterrupler,
double ched< me assembly ~::_-=:_-::=:: =-:- or BS 1212 Part 2 or 3 = -::--:.:-_:--"'-. nq.t opofils!lva!Yo.
Supply- _I Glstem. ;:IP<t
Conlerits fMI ~· harmlti to hoalth
Check vaiYo orBS 1212 Part 2 or 3 f!oal opera~od valw
~ __J
Copyright by the IP, Wed Aug 22 12:55:20 2001
r.·, ! I '....J
rrl . I I...J
n . ,_j
1r1 .......
r' ; . I '-'
0 r: ...,I
0 0 [J
0 c r ....,
r ,....
[
[
r
"""'!': -cY
""1-~
H
ll L:
] '.'' \I
d
-,, r·. II
L
'·· Jl c
l L
...,, J.
Li
J Li ..,
i' .J~. L.:'
l: '' c
l. J'
SECTION A ---------------------·------------~~~--~~~~ Hot and Cold Water Supplies
Type A Air-Giap· A visible, unobstructad and complete gap measured vertically between the lowElst point of discharge of the watGr inlet pipe "' fitting and the sp!i over level of the cistern, vessel or 0111er fitting Into which the now Is discharged.
Table A22 lleqltiml d/meiJI/Dnl all\IJ» A oJr.-Bore of Inlet or feed pipe Minimum wrtical distioce of point
of outlet-. •Pill "'" IMI mm
Not exceeding 14
Exceeding 14 but not e~nQ-21
~lng 21 but not exceeding 41
mm
20
25
70
Exceeding 41 lWJce the bore of the outlet
F/gul8 A13 &le of 8 li'Pe A air-gop BIB dTii'IMJ/f lllp on o link, ¥Ish basin or bath
l.Miol'-'1 part of outlet
Th~ wrtlcal -oo, I istheairgapandls ---- · ----rela:l:ed to the bore of ·
tile piper-~--'-----''-'----./
'JYpe 8 Air-Gap
. SpilkMir Of reoaMng IOSSO·(OOresinded)
A vertical distance between the 111i>ie51 point of discharge Into a cistern, vessel or other fitting and Its steady water level when there Is a maximum inflow of water and all outlets, """"Pt any overflow pipe, are closed. The necessary air-gap must enher be sufficient · to prevent back:slphonage should a vacuum occur In the discharge pipe or fitting, or comply with the appropriate dimensions given In Table A22. .
F/gute AU Elrllmp/e ot a l\lw 8 1/~p pti1V/ded D/ a IIGid WBIIr slotage clllem llttrJJI wilb &BS1Z12 Parl2 or l'lllt 3 flollt Dp~~alld Vllve
Minimum wrtical disiMCe
-· tho OU1Iel of the float ""' Is "lated ro the sil! of feed pipe
ea... l.rJooot part of outk!l
-
Check Valve A mechanical d!Mce incotporating resilient elastic and positively tight seals doslgned to penmlt water to now In one direction only. TJ-..Insti!llation of two check valVes with an Intervening draining tap, known as a 'double check valve assembly', Is an acceptable form of protection at certain points of use Of delivery of water. · · EXllm/Ne . · <lid ritw
NOITllal dlrootion of !low
Pipe lnierrupter A non-mechanical device through which wa!Bf passes and into wt>ich air ca.n enter .through an 1110bstructed annular aperture, "' apertures. When a vacuum occurs on the lnJet side of the device, a correspondirig vacuum is produced on the outlet side, thus plliiiBntlng backsiphonage. Pipe Interrupters need to be correptly located and Installed to a\/Oid any reetrictlon downstream (sg, a stopvalve) that could impose beckp;essure on the del/Ice.
F/gu11 A16 &/B alo p/IJII/nlsmtJ)/Or
Normal drection J1 . offla,v v
'Zl
~.copyright by the IP, Wed Aug 22 12:55:20 2001 l· I