Water Testing-january 2010

7/21/2019 Water Testing-january 2010

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INSTITUTE OF ENGINEERING TECHNOLOGY - KATUNAYAKE

1.1.4 WATER TESTING AND TREATMENT

It is important to control the h!ro"en ion concentration o# $ater tominimi%e corrosion as it ma&es $ater aci!ic $hen the 'H (al)e is lo$*!isc)sse! in the pre(io)s lect)re see notes+,

Chemical a!!iti(es can e a!!e! to con!ition the $ater in or!er tore!)ce the aci!it ie h!ro"en ion concentration an! hence the ph(al)e+ Aci!s lo$er 'H (al)e al&alis increase ph (al)e+

To "i(e al&alinit to $ater the most common a!!iti(es )se! are+ So!i)mh!ro.i!e ca)stic so!a or so!i)m caronate an! Ca*OH,/

It is een st)!ie! in o."en m)st e present to accomplish the #ormationo# metal o.i!e there#ore it is (er important to re!)ce the amo)nt o#

o."en in the $ater $hether it is a coolin" $ater sstem or oiler $atero."en comes mainl #rom the air an! !e aeration can e achie(e! mechanicall or chemicall or a comination o# oth+

0echanical metho! ma e accomplishe! )sin" an air e1ector in thesstem+

Chemicals )se! #or o."en sca(en"in" an! !eaeratin" the $ater2 are)s)all so!i)m s)lphite or h!ra%ine+

So!i)m S)lphite 3 O."en So!i)m s)lphate

/Na/SO4 3 O/ /Na/SO56hen a!!e! to oiler $ater the so!i)m s)lphate $hich is #orme!remains in sol)tion )n!er normal con!itions ca)sin" no prolems+

*Increase oiler $ater !ensit 7 !isa!(anta"e,

Use o# H!ra%ine sol)tion *89: h!ra%ine 59: $ater appro.imatel,

H!ra%ine 3 O."en 6ater 3 Nitro"enN/H5 3 O/ /H/O 3 N/

A!(anta"e o# )sin" h!ra%ine 7 !oes not increase oiler $ater !ensit+*H!ra%ene reacts $ith an metal o.i!e there#ore a controlle! e.cess isene;cial,

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It is important to &no$ the salts presentin" nat)ral $ater an!e(aporate! as it is $i!el )se! #or coolin" o# man machiner an! asma&e )p #ee! #or lo$ press)re oilers+

The salts !issol(e! in nat)ral $ater are metallic salts o# so!i)m20a"enesi)m2 Calci)m+

The stan!ar! metho! o# meas)rin" the metallic salt content parts permillion or '+'+0+

FRESH WATER SAMPLE ANALYSIS

SALT SYMBOL P.P.M.

So!i)m Chlori!e

So!i)m Nitrite

0a"nesi)m S)lphate

Calci)m S)lphate

Calci)m Caronate

Na Cl

Na NO4

0" SO5

Ca SO5

Ca CO4


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ANALYSIS OF SEAWATER

A(era"e sea $ater contains appro.imatel 4/2999 p+p+m+ o# total!issol(e! soli!s+

Salt Chemical Appro.imate : p+p+m+ Smol o# total !issol(e!

soli!s

So!i)m chlori!e Nacl >= /


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Moment

insulation

from water


Calci)m caronate Calci)m caronate 3 Caron !io.i!e 3 $ater

Calci)m caronate has a lo$ sol)ilit an! sol)ilit !ecrease! as tempincrease it can there#ore #orm scale+

Non Al&aline or permanent har!ness salts are the chlori!es2 S)lphates2Nitrates !)e to these salts is not remo(e! oilin" or heatin" the saltscan e remo(e! chemical treatment+

Total har!ness is there#ore is the s)m o# al&aline an! non al&alinehar!ness+

SCALE FORMATION AND SL(DGE FORMATION

Steam )le is #orme! )pon the heatin" s)r#ace the plate )n!er the )leo(erheats as it is ins)late! momentaril #rom the $ater+

The $ater containin" salts is in contact $ith the peripher o# the )le+ I# thesalts are those $hich !ecrease in sol)ilit as temperat)re increases+

The are !eposite! in the #orm o#

a crstal rin"+ This is eca)se the$ater is s)persat)rate! locall$ith the salts+

6hen the )le )rsts the$ater comes in contact $ith theplate o(erheate! plate2 localo(erheatin" occ)rs an! moresalts are !eposite!+

There#ore salts $hose sol)ilit !ecrease $ith increase o# temp are those$hich #orm scale )pon heatin" s)r#aces an! sl)!"e )pon the coolin" s)r#aces+


Bubble

OverheatingPeriphery ofbubble overheats


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Salts $hose sol)ilit increase $ith increase in temp !o not

normall #orm scale )pon heatin" s)r#aces+ @)t sl)!"e ma e#orme! i# their sat)ration point is reache!+

EFFECTS OF (SING SEA WATER AS BOILER FEED WATER

As st)!ie! earlier sea $ater contains #ollo$in"+ issol(e! soli!s2 ieso!i)m Chlori!e - Nacl2 0a"nesi)m Chlori!e 7 0" Cl/2 0a"nesi)mS)lphate2 Calci)m S)lphate2 Calci)m @icaronate 7 Ca*HCO4,+

S)ium C*lri)# +NaCl,

Hea( concentrations - Ca)se #oamin" an! primin"Sol)ilit Bariale - Increase o# temp an! 'ress)re

Slu"i! O- Eac* Sal" I /aria!c# Wi"* T#m

Some chlori!es some not o# sol)tion

/Na Cl/ 3 0" SO5 0" Cl/ 3 Na/SO5

0" Cl/ insol)le )n!er normal oiler con!itions+

0" Cl 3 /H/O 0" *OH,/ 3 /H Cl

0" *OH,/ Lo$ Sol)ilit can !eposit an! #orm scale

HCL Can ca)se corrosion

/ HCL 3 Fe Fe CL/ 3 H/

Fe Cl/ 3 / H/O Fe *OH,/ 3 /HCl



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Corrosi(e Ccle contin)es

Ma0!#ium Sul*a"# +M0 SO4,

Sol)le )n!er normal oiler con!itions

I# !ensit too hi"h eposit #orm scale

Nacl 3 0" SO5 0" Cl/ 3 Na SO5

Calcium Sul*a"# +Ca SO4,

0ost !an"ero)s - Forms scale - Tenacio)s Har!

EDects heat trans#er - Fail)re o# heatin" s)r#ace+

Calci)m icaronate *CaHCO4,ecomposes $hen heate!

Ca*HCO4,/ CaCO4 3 CO/3H/O

CaCO4 - Has lo$ sol)ilit !ecreases $ith increase o# temp can #orm scale

*so#t an! poro)s, not e a! as CaSo5 $hen heat trans#er isconcerne!+

Fr#* 2a"#r a bil#r -##) 2a"#r

It is etter than )sin" sea $ater as the !issol(e! salts are m)ch less than insea $ater chance o# #ormin" an! primin" re!)ce! har!ness salts $ill ca)sescale #ormation to a lesser m)ch !e"ree than sea $ater+ *0ost lo$ press)reoilers )se #resh $ater #or their #ee!,+

Di"ill#) 2a"#r a -##) 2a"#r

O(io)sl (er m)ch less !issol(e! soli!s *m)st #or hi"h press)re oilers+ 6ithhi"h e(aporation rates etc+,



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*@lo$in" !o$n o# oiler re")larl,

THE PRINCIPAL OB3ECTS OF BOILER WATER TREATMENT

*?,+ To pre(ent scale #ormation in oiler an! #ee! sstem+*a,+ Usin" !istille! $ater *@, 'recipitatin" all scale #ormin" salts

into the non a!herin" sl)!"e+

*/,+ To pre(ent corrosion in the oiler an! #ee! sstem maintainin"the oiler $ater in an al&aline con!ition an! #ree #rom !issol(e!"ases+

*4,+ To control the sl)!"e #ormation an! pre(ent carr o(er $ith steam+

*5,+ To pre(ent #orei"n matter enterin" the oiler oil2 $aste2 mill scale2iron o.i!e2 copper particles san!2 $el! spatter+

@e#ore pre commissionin" - clean $ell6atch the !rainso not allo$ corrosion in con!ensate sstem+

PHOSPHATE TREATMENT

4CaCO4 3 /Na4'O5 Ca4*'O5, 34Na/CO4

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Calci)m Caronate 3 Tri So!i)m phosphate Calci)m 3 So!i)m'hosphate caronate

4CaSO5 3/Na4'O5 Ca4*'O5,/ 3 4Na/SO5Calci)m s)lphate 3 Tri So!i)m phosphate Calci)m 3 So!i)m

'hosphate s)lphate

4CaCl/ 3 /Na4'O5 Ca4*'O5,/ 3 8NaClCalci)m Chlori!e 3 Tri So!i)m phosphate Calci)m 3 So!i)m

'hosphate chlori!e

0" SO5 3/Na4'O5 0"4*'O5,/ 3 4Na/SO5Calci)m s)lphate 3 Tri So!i)m phosphate 0a"nesi)m 3 So!i)m

'hosphate S)lphate

@ )sin" in so!i)m phosphates so!i)m caronate is #orme!+ )e to the snea&!o$n o# the so!i)m caronate so!i)m h!ro.i!e is essentiall #orme! an! theirma&es the $ater mo!eratel al&aline+

Tri So!i)m phosphate is !irectl a!! to the oiler since the are ")i!e toreact an! co)l! #orm scale in the #ee! $ater sstem+

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Other phosphate So!i)m Hecata phosphateSo!i)m 'hosphatei So!i)m phosphate 'o)re! !irectl intoTri so!i)m phosphate the @LR+

)e to the calci)m remo(al the phosphate the ten!enc #or these silicatepresent at the $ater to #orm scale is "reatl re!)ce!+ The ten! to remain insol)tion+

'hosphate treatment is s)itale #or lo$ as $ell as hi"h press)re oilers+

LIME AND SODA TREATMENT.

Internal so#tenin" Tra!itionall this is achie(e! In1ectin" lime - Ca*OH,/

an! so!aSo!a ma e in the #orm o# Na/Co4 or ca)stic so!a NaOHLime react $ith temperaror har!nes saltSo!a react $ith permanent har!ness salt+

These chemicals are )se! in con1)nction $ith the s)itale coa")lants s)chas starch an! tannin to con!ition the sl)!"e ;nal to #orm a occ)lent oc&+So!i)m al)minate is )se! to remo(e the traces o# oil #rom the oiler i#s)ch contamionation has ta&en place+

"

The !ensit "i(es an i!ea o# the total !issol(e! soli!s+

An electric salinometer ma also e )se!+

The ran"e o# scales are2

'RESSURE

TY'E OF @OILER

6ATER TU@E

SCOTCH BERTICA )pto ?>+


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499->99 499-


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I# sea $ater is )se! as ma&e )p #ee! #or lo$ press)re oilers it isrecommen!e! that the oiler !ensit sho)l! e maintaine! as close aspossile to A- *appro.+ ?/


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a!! ?9 !rops o# methl-oran"e2 res)lt ello$ colo)ration2 a!! N


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P**a"# T#"

Ta&e 9p+p+m+,+ It $ill e appreciate! that the sample o# oiler $ater

m)st e hot in or!er to !issol(e the crstals+

Har)!# T#"

Ta&e ?99 ml o# oiler $ater sample2

a!! 9+/ ml at a time2 stan!ar! soap sol)tion2sha&e (i"oro)sl a#ter each a!!ition o# soap )ntil a latherpersists #or at least ;(e min)tes+Calc)lation ml o# soap sol)tion )se! . ?9 p+p+m+ CaCO3e)i(alent+

H /alu#A oiler $aterQs pH (al)e can e otaine! three asic metho!s+

*?, Litm)s papers+

*/, Colo)rl metricall+*4, Electrolticall+

The litm)s paper metho! has alrea! een !escrie! )t the test !oes not"i(e a (er acc)rate pH res)lt2 in!icatin" merel i# the $ater is aci!ic oral&aline+ Tests */, an! *4, ho$e(er "i(e a reasonal acc)rate pH (al)e

T"al Dil6#) Sli)

These are ascertaine! )se o# a h!rometer or electrical con!)cti(itmeter+

Hydroeter! "droeter! Us)all "ra!)ate! in "rains per imperial "allon *to con(ert"rains per imperial "allon to p+p+m+ m)ltipl ?5+4,+ Care m)st e ta&en



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$hen )sin" the h!rometer to acco)nt #or the $ater menisc)s an! toascertain acc)ratel the temperat)re o# the sample+ Temperat)re correctiontales #or the h!rometer are )s)all s)pplie! $ith it+

Conducti"ity #eter! A portale2 atter operate!2 electrical con!)cti(itmeter is )se! in this test+ The remo(ale con!)cti(it cell is $ashe! o)t an!;lle! $ith a treate! oiler $ater sample *treatment consists o# coolin" to?< to /9M C2 a!!in" phenolphthalein an! remo(in" pin& colo)ration$ith aci!,+ The ;lle! cell is pl)""e! into the meter2 its temperat)rechec&e! an! the temperat)re control set to correspon!+ A ran"e s$itch is setto appro.imate ran"e o# rea!in" e.pecte!2 then a central control is operate!)ntil Qn)llQ alance o# the electrical ri!"e circ)it *the cell #orms oneresistance, is achie(e!+ 'osition o# the central control in!icates thetotal !issol(e! soli!s in the $ater )s)all in p+p+m+ )t it ma econ!)cti(it in micromhos *to con(ertP p++ p+m+ total !issol(e! soli!s

con!)cti(it in micromhos . 9+>,

WATER SIDE ATTAC7 IN DIESEL ENGINES.

Great importance is attache! to the nee! #or $ater treatment an! it isrecommen!e! that specialist a!(ice is al$as ta&en to protect en"ine #rom



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!ama"e that can e ca)se! the )se o# )ntreate! $ater in en"ine spaces2$here !ama"e has occ)rre! )t is onl correct $ater treatment can ee.pecte! to arrest it+ For mo!em lar"e slo$ spee! t$o stro&e en"ine the)il!er recommen! to )se e(aporate! $ater+ E(aporate! $ater has a lo$sal in i t 2 $hich can pro( i!e the l iner s)r #ace $i th a protecti(e

coatin"+Cast iron clin!er liners an! 1ac&ets are s)1ecte! to the #ollo$in" #orms o#

attac&+

I + Corrosi(e attac&

/+ Gal(anic attac&

4+ Ca(itations erosion5+ Belocit erosion or impin"ement attac&

Corrosive attack

This res)lts #rom the )se o# )ns)itale coolant an!or the incorrect application

o# the $ater treatment+ The presence o# #ree or !issol(e! o."en $ill

accelerate the attac&+ The pH (al)e o# coolant is o# partic)lar importance2

aci!ic $aters $ith pH elo$ se(en $ill attac& #erro)s metals an!

al&aline $aters $ith pH ao(e = $ill attac& al)min)m allo+ 'resence o#

#ree caron !io.i!e can also ca)se this #orm o# attac&+ CO/ is release! $hen

!issol(e! caronate are heate! ao(e >?9C+

Galvanic action

This occ)rs et$een !issimilar metals )ns)itale $ater con!itions+

Cavitations erosion.

It is the res)lt o# (iration o# the clin!er liner $all+ This ca)se thecollapse o# small air or (apor )les an! s)1ects the $all to locali%eh!ra)lic hammerin"+ This #orm o# attac& is )s)all con;ne! to the thr)st#ace o# the clin!er $all+ Attention m)st e pai! to o(er come the ca)seo# anormal (iration e.cessi(e piston slap ma also ca)se this attac&+



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Velocity erosion

This can res)lt #rom e.cessi(e coolant (elocit create! restriction inthe $ater sstem+ This is a""re"ate! the presence o# arasi(e particals+

Cylinder heads

Corrosion o# the clin!er hea! $ater spaces $ill in(arial res)lt #rom)ntreate! 6ater+ The res)ltin" re!)ction in material section can res)lt in#ati")e crac&in" allo$in" lea&a"e o# $ater into the com)stion spaceclin!er hea! crac&in" can also e ca)se! local o(erheatin" !)e eitherto the !eposition o# scale2 loss or re!)ction o# $ater circ)lation or retentiono# air in the coolant passa"es in the hea!+

It is essential that $ater treatment e emploe! in all en"ine coolin"

sstem as soon as the en"ine "oes into ser(ice+ Some inhiitors pro(i!echemical protection an! pH control $hile others !eposit a protecti(e ;lmon the $atersi!e s)r#aces+ Some inhiitors contains anti-#ree%e chemicalsli&e so!i)m en%oate or so!i)m nitrate+

The instr)ction s)pplie! $ith an inhiitor m)st e strictl a!here! topartic)larl in respect to !osa"e stren"th+ The presence o# chlori!es inthe $ater can "reatl a""ra(ate corrosion+ Normall the ma.im)m limito# /


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Sodium Nitrite and sodium silicate

Here so!i)m nitrite pro(i!es protection o# cast iron an! steel an! so!i)msilicate pre(ents attac& on sol!ere! 1oints+

Soluble oils:

This is a special anticorrosion oil $hich is completel imm)lsi;ale in $ateran! acts as a corrosion inhiitor+ 6hen intro!)cin" sol)le oil to an en"inealrea! in ser(ice it is (er essential to ens)re that all r)er hoses arenitrite line! an! other r)er 1oints an! seals in contact $ith the coolant areo# nitrite r)er+

Recommendation for scale and corrosion control in diesel enine

coolin system!

'resent practice is to re!)ce the ris& o# scale #ormation an! corrosion attac& incoolin" sstems )sin" a comination o# acceptale )alit coolin" $ateran! a s)itale corrosion inhiitor+ I# har! $ater is Use! calci)m scale!eposits2 $hich can acc)m)late an! act as an ins)lator2 $hich maca)se o(erheatin" res)ltin" in e.cessi(e clin!er liner $ear an! possile#ract)re corrosion ma also ca)se serio)s !ama"e to clin!er 1ac&ets2pipin"2 p)mps etc+ The $ater )se! in the en"ine sho)l! not ha(e har!ness

contain as calci)m caronate ao(e ?99 ppm an! the chlori!e contain orthe s)lphate contain sho)l! not e.cee!


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$ater "enerators+

n Acts as pH )Der a"ainst lea&a"e o# com)stion "ases in to the coolin"

$ater+

T*# disadvantaes are.

This mi.t)re cannot e )se! in "al(ani%e! pipe $or& or i# sacri;cial %incano!es are ;tte!+ Also it attac&s so#t sol!ers+

C*romatic has the followin advantae

n Ber eDecti(e inhiitor+

n Concentration easil !etermine! color

n Can e )se! in presence o# %inc coatin" or sacri;cial ano!es+

"he disadvantaes are

n 0)st e han!le $ith ca)tion to a(oi! s&in contact+

n Lo$ concentration $ill promote pittin" attac&

n Can not e )se! i# the en"ine $ater is )se! in a #resh$ater "eneratorn

'oisono)s2 there#ore care m)st e ta&en $hen !)mpin"n Foes not act as pH )Der+

Soluble oils has the.f#$owin advantaes.

n Sa#e to han!le

n Appro(e! #or en"ines $here $ater is )se! in #resh $ater "enerators+

n Re!)ce ca(itations eDects

n Gi(es "oo! protection on clean metal s)r#aces+

T*# disadvantaes are.

n I# $ater )alit is not "oo!2 the em)lsion can loose stailit an! oil "ets

separate! o)t+n The sstem m)st &eep asol)tel clean+

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n Ten!enc to #orm eat ins)latin" laers o# soli! s)stances $ith

separate! oil actin" as on!in" a"ent+n Hi"h concentration can ca)se o(erheatin"+

n Foamin" ma ta&e place i# $ater has (er lo$ har!ness+


Water Testing-january 2010

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