Post on 12-Jul-2018
A = Area (ft²) IP, (m²) SI M = Mass (lb) IP, (kg) SI
ACH = Air Changes per Hour ma = Mixed Air
Ak = Effective Area m = meter (metre)
AV = Average m³/s = Volumetric Flow: Cubic Meters Per Second
BHP = Brake Horsepower (IP) HP NLA = No Load Amperage
BP = Brake Power (SI) kW NPSHA = Net Positive Suction Head Available
Btu = British Thermal Unit oa = Outside Air
Btu/h = Btuh = BTUH = BTU/Hour % oa = % of Outside Air
= Center Distance (used in belt formula) Ω = Ohm
°C = Degrees Celsius, °C P = Pressure
C = Friction Loss Coefficient (For Duct Fittings) Pa = Atmospheric Pressure
CCF = 100 Cubic Feet Pab = Absolute Pressure (Atmospheric Pressure + Gauge Pressure)
CFM = Volumetric Flow: Cubic Feet Per Minute Pa = Pascals, Pressure SI
Cp = Specific Heat π = 3.14
Cv = Flow Constant (IP) PD = Sheave Pitch Diameter
ρ = Density (lb/ft³) IP, (kg/m³) SI P = Pressure at Pump Centerline
d = Diameter (in.) IP, (mm) SI ppm = parts per million
Δ = Difference or Change (Final - Initial) psi = Pounds Per Square Inch
dimp = Impeller Diameter psia = Pounds Per Square Inch Absolute
E = Volts psig = Pounds Per Square Inch Gauge
Eff = Efficiency Pvp = Absolute Vapor Pressure
EP = Pump Efficiency Q (flow) = Volumetric Fluid Flow Rate: (i.e. CFM, GPM, m³/s, l/s, etc.)
°F = Degrees Fahrenheit, °F Q (heat) = Heat Flow Rate (BTU/Hour) IP, (W or kW) SI
f = Friction Factor °R = °Rankin = Degrees Rankin, °R
FLA = Full Load Amps r = Radius (in) IP, (mm) SI
fpm = Feet per Minute (fpm) % ra = % of Return Air
ft = Foot R = Resistance
g = Acceleration of Gravity ra = Return Air
gal = Gallons rad = Radians
GPM = Gallons Per Minute (GPM) RH = Relative Humidity
h = Enthalpy (BTU/lb dry air) IP, (kJ/kg dry air) SI RPM = Revolutions Per Minute
H = Head (in wc, ft wc, psi) IP, (Pa, kPa) SI Rvalue = Thermal Resistance
Hg = Mercury s = second
hma = Mixed Air Enthalpy SHR = Sensible Heat Ratio
hoa = Outside Air Enthalpy SME = Sash Movement Effect Performance Rating (SME-XX yyy)
HP = Horsepower SP = Static Pressure
hr = Hour Sp Gr = Specific Gravity (for water use 1.00)
hra = Return Air Enthalpy T = Temperature
HT = Height (in) IP, (mm) SI Ta = Absolute Temperature (460˚ + T) or °R
I = Amps Tma = Mixed Air Temperature
J = Joules Toa = Outside Air Temperature
K = Kelvin, K TP = Total Pressure
Kv = Flow constant (SI) Tra = Return Air Temperature
kg = Kilogram TS = Tip Speed (fpm) IP, (m/s) SI
kJ = Kilojoule U = Heat Transfer Coefficient
kPa = Kilopascal µ = viscosity, dynamic
kW = Kilowatt = 1000 Watts V = Velocity
l = Liter (Litre) VP = Velocity Pressure
l/s = Volumetric Flow: Liters Per Second W = Watt
lb = Pounds WD = Width (in) IP, (mm) SI
lm = Lumens wg = wc = water gauge = water column
ln = natural log WHP = Water Horsepower (IP)
LG = Length (in) IP, (mm) SI WP = Water Power (SI)
lx = Lux ω = Humidity Ratio (lb or grains of water/lb of dry air) (g H2O/kg dry air)
NEBB Fundamental Formulas
Approved NEBB - January 11, 2018 Page 1 of 8 Version 1.31
Airflow & Velocity Equations
Q V A Q VxA
TP VP SP TP VP SP
V 4005 √VP V 1.66 VP
V 1096VP
V 1.414VP
ACHQ 60
LGxWDxHT ACH
Q 3600 LGxWDxHT
Areaπ
d2
144π r144
Areaπ
d2
1,000,000π r
1,000,000
Area /HT WD144
Area /HT WD1,000,000
Area
HT x WD-HT π 2HT
144 Area
HT (WD - HT π 2HT
1,000,000
Air Temperature Equations
1.8 32° 32 1.8
°R 460 K 273
T % T % T h % h % h
%T TT T
100 %h hh h
100
Heat Transfer Calculations
Q 4.5 CFM ∆h Q 1.2 l s ∆h
Q 60 Cp ρ CFM ∆T Q Cp ρ l s ∆T
Q 1.08 CFM ∆T Q 1.23 l s ∆T
Q 0.69 CFM ∆ Q 3.0 l s ∆
Q 4840 CFM ∆
SHR Q Q Q Q Q
Q A U ∆ Q A U ∆
Fan Equations
CFMCFM
RPMRPM
l sl s
m sm s
rad srad s
PP
CFMCFM
PP
l sl s
m sm s
BHPBHP
CFMCFM
kWkW
l sl s
m sm s
TipSpeed TSπ d rpm
12TipSpeed TS
π d rpm60
NEBB Fundamental Formulas
Approved NEBB - January 11, 2018 Page 2 of 8 Version 1.31
Sheave Equations
RPMPDPD
RPM RPMRPM
PDPD
FanBeltLength 2 1.57 PD PDPD PD
4
Electrical Equations
Power E I 1 kW 1000Watts
I E Ω Ω E I
1HP 746Watts 1Watt 3.413Btu/hr
Power Equations
BHP E I PF Eff
746PF PowerFactor
kW E I PF1000
PF PowerFactor
BHP E I PF Eff 1.732
746PF PowerFactor 0.8&Eff 0.9;ifnotgiven
kW E I PF 1.732
1000
BHP HPI NLA 0.5FLA NLA 0.5
FLAFLA E
E
FanHPCFM TP SpGr
6356 Eff
Resistance
SeriesCircuit:totalresistance:Ω R ParallelCircuit:totalresistance:Ω R
R R R R ⋯ R 1
R1R
1R
⋯1R
E I E I VoltageDrop I R
Conversions
kilowatts Kw Btu/hr 3413
horsepower HP Btu/hr 2545
joules Btu/hr 0.000948
kilogramcalories Btu/hr 3.968
tonsofcooling chiller Btu/hr 12000
tonsofcooling coolingtower Btu/hr 15000
gallonsU.S. water poundsU.S. lb. 8.33
millimeters inchesU.S. 25.4
centimeters inchesU.S. 2.54
bar poundspersquareinch PSI 14.5
inchesofwater poundspersquareinch PSI 0.036
inchesofMercury Hg poundspersquareinch PSI 0.491
NEBB Fundamental Formulas
Approved NEBB - January 11, 2018 Page 3 of 8 Version 1.31
Hydronic
Pump Equations
GPMGPM
RPMRPM
l sl s
m sm s
rad srad s
GPMGPM
d
d
m sm s
d
d
HH
GPMGPM
HH
mh
mh
rad srad s
BHPBHP
GPMGPM
BPBP
m sm s
rad srad s
WHPGPM H SpGr
3960
SpGr 1.0, unlessgiven, EPuse0.7ifnotgiven
WP 9.81 m s H SpGr
WPl s H SpGr
1002
BHPGPM H SpGr
3960 EP
SpGr 1.0, unlessgiven, EPuse0.7ifnotgiven
BPWPEP
EP %WHP 100
BHPEP %
WP 100BP
Hydronic Calculations
Coil∆P:GPM GPMPP
Coil∆P: m hm
hPP
CGPM SpGr
∆PK
mh SpGr
∆P
GPMC ∆P
SpGrSpGr 1.0, unlessgiven, EPuse0.7ifnotgiven
mh
C ∆P
SpGrSpGr 1.0, unlessgiven, EPuse0.7ifnotgiven
∆P SpGrGPMC
SpGr 1.0, unlessgiven, EPuse0.7ifnotgiven
∆P SpGrm
hK
SpGr 1.0, unlessgiven, EPuse0.7ifnotgiven
NPSHA P PV2g
P P
Heat Transfer Calculations
ρ ∆ ρ ∆
500 ∆ 4190 ∆
4190 ∆
Boiler Calculations
OutputBtu InputBtu %Eff FireRateInputBtu
FuelBtu
BoilerOperatingCost FireRate hrsBurned $Costgal Btu lbofwater 500 ∆T
NEBB Fundamental Formulas
Approved NEBB - January 11, 2018 Page 4 of 8 Version 1.31
Metric Equivalents
acceleration m/s2 meterspersecondsquared 1m/s2 3.281ft/sec2
airflowvolumetricflowrate
m3/s cubicmeterspersecond 1m3/s 2118.88cfm
l/s literspersecond 1l/s 2.12cfm
m3/hr cubicmetersperhour 1m3/hr 0.589cfm
aream2 squaremeter 1m2 10.764ft2
mm2 squaremillimeters 1mm2 0.0016in2
atmosphericpressure
kPa kiloPascals 101.325kPa 29.92inHg 14.696psi
Bar Barometers 1Bar 100kPa 29.53inHg 14.504psi
distance.length,ordistance
m meter 1m 3.281ft
m meter 1m 39.370in
mm millimeter 1mm 0.039in
lightingintensitylx Lux 1lx 0.093fc
lm/m2 Lumens/squaremeter 1lm/m2 0.0931fc
pressurekPa kiloPascals 1000Pascals 1kPa 0.296inHg 0.145psi
Pa Pascals 1Pa 0.004inwg
temperature °C degreesCelsius °C °F‐32 /1.8
velocity m/s meterspersecond 1m/s 196.9fpm
volume m3 cubicmeters 1m3 35.31ft3
1Btu Energyrequiredtoheat1lbofH2Ofrom39˚Fto40˚F
1CCF 100000Btu
1ft inches 12
1ftwc 0.434psi
1ftHg 5.89psi
inches ftx12
1mmHg 0.535inwc
1inHg 1.133ft
1kW/hr 3413Btu
1lb moisture 7000grains
1psi 2.307ftwc
1psi 27.681inwc
1psi 2.036inHg
1Tonrefrigeration 12000Btu/hr
Atmospheric.Press 29.92inHgor14.69psi
DensityofAir Std 0.075lb/ft3
DensityofWater Std 62.4lb/ft3or7.49gal/ft3or8.33lb/gal
Onefootofmercury Hg column 5.89lb/in2 psi
Oneinchofmercury Hg column 13.6inches inwg 1.13ftwg
SpecificHeat Cp ofdryair 0.24Btu/lbx˚F@68°F
SpecificHeat Cp ice 0.50Btu/lbx˚F@68°F
SpecificHeat Cp vapor 0.45Btu/lbx˚F@68°F
SpecificHeat Cp water 1.00Btu/lbx˚F@68°F
SpecificVolumeofAir Std 13.33ft3/lb
NEBB Fundamental Formulas
Approved NEBB - January 11, 2018 Page 5 of 8 Version 1.31
-10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 125 130
DRY BULB TEMPERATURE - °F
10
20
30
40
50
60
70
80
90
100
110
120
130
140
150
160
170
180
190
200
210
10 15 20 25 3035
40
45
50
55
55
60
60
65
70
ENTH
ALPY
- BT
U P
ER P
OU
ND
OF
DR
Y AI
R
0
5
10
15
20
25
30
35
40
45
50
ENTH
ALPY
- BT
U PE
R PO
UND
OF
DRY
AIR
SATU
RATI
ON
TEM
PERA
TURE
- °F
-50
05
510
1015
1520
20 25
25 30
3035
35 40
40 45
45 50
50 55
55 60
6065
6570
70
75
75
80
80
85 WET BULB TEMPERATURE - °F
85
90
15%
25%
2 %
4 %
6 %
8 %
1 0 % R E L A T I V E H U M I D I T Y2 0 %
3 0 %
4 0 %
5 0 %
60%
70%
80%
90%
12.0
12.5
13.0
13.5
14.0 SPECIFIC
VOLU
ME ft³/lb O
F DR
Y AIR
14.5
15.0
15.5
HU
MID
ITY
RAT
IO -
GR
AIN
S O
F M
OIS
TUR
E PE
R P
OU
ND
OF
DR
Y AI
R
PSYCHROMETRIC CHARTBAROMETRIC PRESSURE 29.921 inches of Mercury
Linric Company Psychrometric Chart, www.linric.com
.1
.2
.3
.4
.5
.6
.7
.8
.9
1
1.1
1.2
1.3
VAPO
R P
RES
SUR
E - I
NC
HES
OF
MER
CU
RY
-20 0
10
20 25
30
35
40
45
50
55
60
65
70
75
80
85
DEW
PO
INT
- °F
0
1.0 1.0
2.0
84.0- 8.
- -8.04.0-2 0.-1.0- -0.540.-0.3-0.2-0.1
0.10.20.3
0.4
0.50.6
0.8
-2000-1000
0.0
50.0
1000
1500
2000
3000
5000
-
SENSIBLE HEAT QsTOTAL HEAT Qt
ENTHALPYHUMIDITY RATIO
hW
NEBB Fundamental Formulas
Approved NEBB - January 11, 2018 Page 6 of 8 Version 1.31
5 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70
DRY BULB TEMPERATURE - °C
-30 -20 -10 0 10 20 30 40 50 60 7080
90
100
110
120
130
140
150
150
160
160
170
170
180
180
EN
THA
LPY
- K
J P
ER
KIL
OG
RA
M O
F D
RY
AIR
-30
-20
-10
0
10
20
30
40
50
60
70
80
90
100
110
120
130
140
ENTH
ALPY
- KJ
PER
KIL
OG
RAM
OF
DRY
AIR
1.02.03.04.05.06.07.08.09.010.011.012.013.014.015.016.017.018.0
19.020.021.0
22.0
23.0
24.0
25.0
26.0
27.0
28.0
29.0
30.0
31.0
32.0
33.0
34.0
35.0
36.0
37.0
38.0
39.0
40.0
41.0
42.0
43.0
44.0
45.0
46.0
47.0
VA
PO
R P
RE
SS
UR
E -
MM
OF
ME
RC
UR
Y
-10
-5
0
5
10
15
20
25
30
35
DE
W P
OIN
T TE
MP
ER
ATU
RE
- °C
1.00
0.95
0.90
0.85
0.80
0.75
0.70
0.65
0.60
0.55
0.50
0.45
0.400.350.300.250.20
SENSIBLE HEAT RATIO = Qs / Qt
SE
NS
IBLE
HE
AT
RA
TIO
= Q
s / Q
t
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
15%
25%
2%
4%
6%
8% RELATIVE HUMIDITY
10% RELATIVE HUMIDITY20%
30%
40%
50%
60%
70%
80%
90%
-30 -25 -20 -15-15 -10
-10 -5
-5
05
510
10
15
15
20
20
25
25
30
30
35 WET BULB TEMPERATURE - °C
35
0.76
0.78
0.80
0.82
0.84
0.86
0.88 VOLU
ME - C
UBIC
METER
PER KG
DR
Y AIR0.90
0.92
0.94
0.96
0.98 1.00
1.02
HU
MID
ITY
RA
TIO
- G
RA
MS
MO
ISTU
RE
PE
R K
ILO
GR
AM
DR
Y A
IR
0
1.0 1.0
-
2.04.08.0-8.0-4.0-2.0-1.0-0.5
-0.4-0.3-0.2-0.1
0.10.20.3
0.4
0.50.6
0.8
-4.6
-2.3
0.0
1.2
2.3
3.5
4.7
7.0
11.7
-
SENSIBLE HEAT QsTOTAL HEAT Qt
ENTHALPYHUMIDITY RATIO
hW
-35 -30 -25 -20 -15 -10 -
PSYCHROMETRIC CHARTPSYCHROMETRIC CHART - METRICNORMAL TEMPERATURENORMAL TEMPERATURESI UnitsSI Units
SEA LEVELSEA LEVELBAROMETRIC PRESSURE: 101.325 kPaBAROMETRIC PRESSURE: 101.325 kPa
NEBB Fundamental Formulas
Approved NEBB - January 11, 2018 Page 7 of 8 Version 1.31
Sea Level 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
29.92 28.86 27.82 26.82 25.84 24.90 23.98 23.09 22.22 21.39 20.58
407.50 392.80 378.60 365.00 351.70 333.90 326.40 314.80 302.10 291.10 280.10-40° 1.26 1.22 1.17 1.13 1.09 1.05 1.01 0.97 0.93 0.90 0.87-0° 1.15 1.11 1.07 1.03 0.99 0.95 0.91 0.89 0.85 0.82 0.7940° 1.06 1.02 0.99 0.95 0.92 0.88 0.85 0.82 0.79 0.76 0.7370° 1.00 0.96 0.93 0.89 0.86 0.83 0.80 0.77 0.74 0.71 0.69
100° 0.95 0.92 0.88 0.85 0.81 0.78 0.75 0.73 0.70 0.68 0.65150° 0.87 0.84 0.81 0.78 0.75 0.72 0.69 0.67 0.65 0.62 0.60200° 0.80 0.77 0.74 0.71 0.69 0.66 0.64 0.62 0.60 0.57 0.55250° 0.75 0.72 0.70 0.67 0.64 0.62 0.60 0.58 0.56 0.54 0.51300° 0.70 0.67 0.65 0.62 0.60 0.58 0.56 0.54 0.52 0.50 0.48350° 0.65 0.62 0.60 0.58 0.56 0.54 0.52 0.51 0.49 0.50 0.45400° 0.62 0.60 0.57 0.55 0.53 0.51 0.49 0.48 0.46 0.44 0.42450° 0.55 0.56 0.54 0.52 0.50 0.48 0.46 0.45 0.43 0.42 0.40500° 0.58 0.53 0.51 0.49 0.47 0.45 0.44 0.43 0.41 0.39 0.38550° 0.53 0.51 0.49 0.47 0.45 0.44 0.52 0.41 0.39 0.38 0.36600° 0.50 0.48 0.46 0.45 0.43 0.41 0.40 0.39 0.37 0.35 0.34700° 0.46 0.44 0.43 0.41 0.39 0.38 0.37 0.35 0.34 0.33 0.32800° 0.42 0.40 0.39 0.37 0.36 0.35 0.33 0.32 0.31 0.30 0.29
60° 150° 200° 250° 300° 340°1.046 1.070 1.090 1.110 1.150 1.165
Sea Level 250 500 750 1000 1250 1500 1750 2000 2500 3000
101.33 98.30 96.30 93.20 90.20 88.20 85.10 83.10 80.00 76.00 71.90
0° 1.08 1.05 1.02 0.99 0.96 0.93 0.91 0.88 0.86 0.81 0.76
20° 1.00 0.97 0.95 0.92 0.89 0.87 0.84 0.82 0.79 0.75 0.71
50° 0.91 0.89 0.86 0.84 0.81 0.79 0.77 0.75 0.72 0.68 0.64
75° 0.85 0.82 0.80 0.78 0.75 0.73 0.71 0.69 0.67 0.63 0.60
100° 0.79 0.77 0.75 0.72 0.70 0.68 0.66 0.65 0.63 0.59 0.56
125° 0.74 0.72 0.70 0.68 0.66 0.64 0.62 0.60 0.59 0.55 0.52
150° 0.70 0.68 0.66 0.64 0.62 0.60 0.59 0.57 0.55 0.52 0.49
175° 0.66 0.64 0.62 0.62 0.59 0.57 0.55 0.54 0.52 0.49 0.46
200° 0.62 0.61 0.59 0.57 0.56 0.54 0.52 0.51 0.49 0.47 0.44
225° 0.59 0.56 0.56 0.54 0.53 0.51 0.50 0.48 0.47 0.44 0.42
250° 0.56 0.55 0.53 0.52 0.50 0.49 0.47 0.46 0.45 0.42 0.40
275° 0.54 0.52 0.51 0.49 0.48 0.47 0.45 0.44 0.43 0.40 0.38
300° 0.51 0.50 0.49 0.47 0.46 0.45 0.43 0.42 0.41 0.38 0.36
325° 0.49 0.48 0.47 0.45 0.44 0.43 0.41 0.40 0.39 0.37 0.35
350° 0.47 0.46 0.45 0.43 0.42 0.41 0.40 0.39 0.38 0.35 0.33
375° 0.46 0.44 0.43 0.42 0.41 0.39 0.38 0.37 0.36 0.34 0.32
400° 0.44 0.43 0.41 0.40 0.39 0.38 0.37 0.36 0.35 0.33 0.31
450° 0.41 0.40 0.38 0.37 0.36 0.35 0.34 0.33 0.32 0.31 0.29
500° 0.38 0.37 0.36 0.35 0.34 0.33 0.32 0.31 0.30 0.28 0.27
15.5° 65.5° 93.2° 121° 148.7° 170.9°
Water Temperature °FFeet head differential per inch Hg differential
Air Density Correction Factors (US Units) Standard Air Density (Sea Level & 70°F) = 0.075 lb/ft3 @ 29.92 in Hg
Air Temperature °F
Altitude (ft)
(in wg)
Barometer (in Hg)
Water Temperature °C
Air Density Correction Factors (Metric Units) Standard Air Density (Sea Level & 20°C) = 1.204 kg/m3 @ 101.325 kPa
Altitude (m)
Barometer (kPa)
Air Temperature °C
NEBB Fundamental Formulas
Approved NEBB - January 11, 2018 Page 8 of 8 Version 1.31