GAS CORRECTION FORMULA
Air Equivalent Flow Rate = 
Customer Gas Flow Rate
X Gas Correction Factor 

Step 1: 
Convert Customer Gas Flow Rate unit of measure to a standard unit of measure for air flow (SCFM or SCCM).

Step 2: 
Calculate Gas Correction Factor from given values.

Step 3: 
Calculate the product of the Air Equivalent Flow Rate from the Customer Gas Flow Rate and the Gas Correction Factor.

Step 4: 
Calculate the maximum or minimum flow rate for the customer’s conditions. 
Step 1: Convert Customer Gas Flow Rate unit of measure to
a standardunit of measure for air flow
Customer Gas Flow Rate ________________
Converted Gas Flow Rate ________________ SCFM / SCCM
Gas Flow Rate Conversions

From 
To SCFM 

From 
To SCCM 
SCFH 
Divide by 60 

SCFM 
Multiply by 28,317 
SCIM 
Divide by 1,728 

SCFH 
Multiply by 472 
SLPM 
Divide by 28.317 

SCIM 
Multiply by 16.39 
SM³/MIN 
Multiply by 35.31 

SLPM 
Multiply by 1,000 
SM³/HR 
Multiply by 0.5885 

SLPH 
Multiply by 16.67 
NM³/MIN 
Multiply by 37.99 

SM³/MIN 
Multiply by 1,000,000 
NM³/HR 
Multiply by 0.6331 

SM³/HR 
Multiply by 16,667 
SCCM 
Divide by 28,317 

NM³/MIN 
Multiply by 1,075,785 
KG/MIN 
Multiply by (29.39 ÷ SpGr) 

NM³/HR 
Multiply by 17,929 
KG/HR 
Multiply by (0.49 ÷ SpGr) 

KG/MIN 
Multiply by (832,000 ÷ SpGr) 
LBS/MIN 
Multiply by (13.33 ÷ SpGr) 

KG/HR 
Multiply by (13,876 ÷ SpGr) 
LBS/HR 
Multiply by(0.2222 ÷ SpGr) 

LBS/MIN 
Multiply by (377,500 ÷ SpGr) 
LBS/DAY 
Multiply by (0.00926 ÷ SpGr) 

LBS/HR 
Multiply by (6,292 ÷ SpGr) 
ACFM 
Multiply by [[(Operating PSIG+14.7)(530)] ÷ [(14.7)(Operating °F+460)]] 

Step 2: Calculate Gas Correction
Factor from given values
This information is required to size for conditions other than air at STP:
• Operating Temperature: _________°F
• Operating Back Pressure:_________ PSIG
• Specific Gravity of Gas: _________ @STP
Temperature Conversions


Gas Density Conversions

From 
To °Fahrenheit 

From 
To Specific Gravity 
°Centigrade 
(°C X 1.8) + 32 

LBS/FT³ 
Divide by 0.075 
°Kelvin 
(°K – 273.15)1.8 + 32 

KG/M³ 
Divide by 1.2 
°Rankine 
°R – 459.67 

MolWt 
Divide by 29.0 



g/cm³ 
Divide by 0.0012 
Pressure Conversions

From 
To PSIG 

From 
To PSIG 
foot Water 
Divide by 2.308 

Pa 
(Pa÷101,300)
X 14.7 
Inch Water 
Divide by 27.73 

PSIA 
Minus 14.7 
mm Water 
Divide by 704 

ATM 
(ATM X 14.7) – 14.7 
inch Hg 
Divide by 2.036 

Torr 
((Torr÷760)
X14.7) – 14.7 
mm Hg 
Divide by 51.7 

Bars 
((Bars÷1.013)
X14.7) – 14.7 
kg/cm² 
Multiply by 14.228 

Millibar 
((Millibars÷1013)
X 14.7) –14.7 
kPa 
(kPa÷101.3)
X 14.7 



Gas Correction Factor (GCF) formula:
GCF = _________________
Step
3: Determine the Air Equivalent Flow Rate.
Air Equivalent Flow Rate = Customer Gas Flow Rate x Gas Correction
Factor
Air Equivalent Flow Rate = ____________________
Step
4: Calculate
the maximum or minimum flow rate for the
customer’s conditions (Customer Gas Flow Rate Scale)
Customer Gas Flow Rate
Scale = Catalog Flow Rate ÷ Gas Correction Factor
Customer Gas Flow Rate Scale = ______________________ 