# Technical Resources

Conversions, Formulas, and Engineering Data

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