Flowmeter Sizing Calculations
Gas Flowmeter Sizing
Click Here To Download A PDF Version Of The Sizing Calculations
Variable area flowmeters suitable for liquid service have a capacity rating based on water at 70° Fahrenheit. Flowmeters suitable
for gas service have a capacity rating based on air at STP (70°F, 14.7 PSIA) conditions. The correction factors listed below are
used to calculate the flow capacity when using a liquid other than water or a gas other than air at STP conditions.
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 standard unit 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:
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 = ______________________
Liquid Flowmeter Sizing
Click Here To Download A PDF Version Of The Sizing Calculations
Variable area flowmeters suitable for liquid service have a capacity rating based on water at 70°Fahrenheit. Flowmeters
suitable for gas service have a capacity rating based on air at STP (70°F, 14.7 PSIA) conditions. The correction factors
listed below are used to calculate the flow capacity when using a liquid other than water or a gas other than air at STP conditions.
LIQUID CORRECTION FORMULA
Water Equivalent Flow Rate = Customer Liquid Flow Rate X Liquid Correction Factor
Step 1: Convert Customer Liquid Flow Rate unit of measure to a standard unit of measure for water flow (GPM or CC/MIN).
Step 2: Calculate Liquid Specific GravityCorrection Factor from given values.
Step 3: Determine the Water Equivalent Flow Rate from the product of the Customer Liquid Flow Rate and the Liquid Correction Factor.
Step 4: Calculate the maximum or minimum flow rate for the customer’s conditions.
Step 1: Convert the Customer Liquid Flow Rate unit of measure to a standard unit of measure for water flow.
Customer Liquid Flow Rate ________________
Converted Liquid Flow Rate _________________GPM / CC/MIN
| Liquid Flow Rate Conversions | ||||
| From | To GPM | From | To CC/MIN | |
| GPH | Divide by 60 | GPM | Multiply by 3,785 | |
| CC/MIN | Divide by 3,785 | GPH | Multiply by 63.08 | |
| CC/HR | Divide by 227,100 | CC/HR | Divide by 60 | |
| LPM | Multiply by 3.785 | LPM | Multiply by 1,000 | |
| LPH | Multiply by 227.1 | LPH | Multiply by 16.67 | |
| M³/MIN | Multiply by 264.2 | M³/MIN | Multiply by 1,000,000 | |
| M³/HR | Multiply by 4.402 | M³/HR | Multiply by 16,667 | |
| PINTS/MIN | Divide by 8 | PINTS/MIN | Multiply by 473.1 | |
| FT³/MIN | Multiply by 7.48 | FT³/MIN | Multiply by 28,320 | |
| FT³/HR | Divide by 8.021 | FT³/HR | Multiply by 472 | |
| KG/MIN | Multiply by (0.264 ÷ SpGr) | KG/MIN | Multiply by (1,000 ÷ SpGr) | |
| KG/HR | Divide by (227 X SpGr) | KG/HR | Multiply by (16.67 ÷ SpGr) | |
| LBS/MIN | Divide by (8.347 X SpGr) | LBS/MIN | Multiply by (453.6 ÷ SpGr) | |
| LBS/HR | Divide by (500.8 X SpGr) | LBS/HR | Multiply by (7.56 ÷ Spgr) | |
| GMS/MIN | Divide by (3,785 X SpGr) | GMS/MIN | Divide by SpGr | |
| GMS/HR | Divide by (227,000 X SpGr) | GMS/HR Multiply by 3.785 | Divide by (60 X SpGr) | |
Step 2: Calculate the Liquid Correction Factor from the given values
This information is required to size for liquids other than water:
Specific Gravity of Liquid:____________ @ Operating Conditions
Liquid Temperature:__________°F @ Operating Conditions
Liquid Viscosity: _________cps @Operating Conditions
Specific Gravity of the Float to be used: ___________
| Teflon | 2.20 | 316 SS | 8.04 | From | To Specific Gravity | |
| Glass | 2.53 | Hastelloy C | 8.94 | LBS/FT³ | Divide by 62.4 | |
| Sapphire | 3.99 | Carboloy | 15.00 | KG/M³ | Divide by 1,000 | |
| Titanium | 4.50 | Tantalum | 16.60 | API | [141.5 ÷ (131.5+API)] | |
| 316L SS | 8.03 | g/cm³ | = SpGr | |||
Liquid Specific Gravity Correction Factor (LSGCF) formula:
3. Determine the Water Equivalent Flow Rate
Water Equivalent Flow Rate = Customer’s Liquid Flow Rate ÷ LSGCF Water Equivalent Flow Rate = ______________________
4. Calculate the maximum or minimum flow rate for the customer’s conditions. (Customer Liquid Flow Rate Scale)
Customer Liquid Flow Rate Scale = Catalog Flow Rate ÷ LSGCF @ 70° F
Customer Liquid Flow Rate Scale = ____________________