Conversions, Formulas, and Engineering Data
Technical Resources
Pressure Conversions
1 PSI = 27.71 inches water
1 PSI = 2.0418 in. Hg @ 60F
1 PSI = 51.81 mm Hg @ 60F
1 PSI = .0689 bar
1 PSI = 6.895 kPa
1 inch water = 1.8718 mm Hg
1 inch water = .2489 kPa
Volume Conversions
1 Gallon = .1337 cubic feet
1 Gallon = 231 cubic inches
1 Gallon = .003785 cubic meters
1 Gallon = 3.785 liters
1 Barrel (oil) = 42 gallons
1 Bushel = 1.2445 cubic feet
Mass Conversions
1 lb. = .4536 Kg
1 Ton (short) = 2000 lbs.
Volumetric Flow
1 GPM = .227 cubic meters/hour
1 GPM = 3.785 liters per minute
Distance
1 inch = 2.54 centimeters
1 foot = .3048 meters
Water Density
At 60 degrees F = 62.371 lbs/ft.
At 60 degrees F = 8.3378 lbs./gal.
Steam Data
Gage Press. Temp Spec. Volume
PSIG Deg. F Cubic ft/minute
0.0 212 26.8
25.3 267.25 10.5
50.3 297.97 6.66
100 337.90 3.88
101 365.99 2.75
200.3 377.89 2.13
250.3 406.13 1.74
Pressure
PSI (absolute) = PSI (gauge) +14.696
Flow Velocity of Water
V(ft./second) = .4086*Q/D*D
Q is flow in GPM
D is pipe ID in inches
Table of Liquid Flows in
Schedule 40 pipe
Pipe Size GPM at 3 fps GPM at 15 fps
1 8.086 40.43
1.5 19.026 95.13
2 31.358 156.79
3 69.12 345.6
4 119.046 595.23
5 270.27 1351.35
8 468.748 2343.74
10 738.342 3691.71
11 1044.78 5223.88
12 1651.38 8256.88
24 3761.76 18,808.78
Flow Velocity of Gas
V = 3.056*Q/D*D
V is flow velocity in SFPS
Q is flow in SCFM
D is pipe ID in inches
Volumetric Gas Flow
SCFM = ACFM*(pf*520)/(14.7*Tf)
Pf = Pressure at flow conditions PSIA
Tf = Temp. at flow conditions Deg. R
Volumetric to Mass Flow of Water
33F water, 8.325 lb./gallon density
Q(GPM) = Q(lbs/hour)*.002
Control Valve Sizing
Liquid
Cv = q*Ã(gf/DP)
Steam
Cv = W/(2.1*Ã(DP(Pf1+Pf2))
Gas
CV = Q/963*Ã((G*Tf/DP(Pf1+Pf2))
q is GPM, Ã is Square Root
gf is liquid specific gravity
DP is Differential pressure
W is steam flow rate lbs./hr
Pf1 upstream pressure in psia
Pf2 downstream pressure in psia
Q is gas flow rate