Propane Flow Rate Calculator
Calculate gas demand (CFH) and estimated pipe size requirements based on BTU load.
Low Pressure (11″ Water Column)
High Pressure (2 PSI)
Schedule 40 Iron Pipe
Type L Copper Tubing
Cubic Feet per Hour (CFH):
–
Gallons per Hour (GPH):
–
BTU per Cubic Foot used:
2,500
Suggested Min. Pipe ID (approx):
–
How to Calculate Propane Flow Rate
Understanding the flow rate of propane is critical for ensuring that your gas appliances receive adequate fuel for safe and efficient operation. Gas flow is typically measured in Cubic Feet per Hour (CFH) or BTUs per Hour.
The fundamental formula used in this calculator is:
CFH = Total BTU Load / 2,500
This is based on the industry standard that one cubic foot of propane contains approximately 2,500 to 2,516 BTUs. If you need to know how many gallons of liquid propane you are burning, the conversion is roughly 91,502 BTUs per gallon.
Key Factors in Propane Pipe Sizing
- BTU Input: Sum of the maximum nameplate ratings of all appliances connected to the line.
- Pipe Length: The total distance from the regulator to the furthest appliance. Longer runs result in greater pressure drops.
- Pressure Drop: Systems are typically designed for a specific allowable pressure drop (usually 0.5 inches Water Column for low-pressure systems).
- Material: Friction factors change between smooth copper tubing and rougher black iron pipe.
Realistic Example
Imagine you are installing a tankless water heater (199,000 BTU) and a gas range (60,000 BTU). Your total load is 259,000 BTU.
- Flow Rate: 259,000 / 2,500 = 103.6 CFH.
- Gallons Per Hour: 259,000 / 91,502 = 2.83 GPH.
- If this setup is 40 feet from the regulator, you would typically require at least a 3/4″ or 1″ iron pipe depending on specific local codes and pressure drop tolerances.
Safety Disclaimer
This calculator provides estimates for planning purposes only. Propane piping systems must be designed and installed by qualified professionals in accordance with NFPA 54 (National Fuel Gas Code) and NFPA 58 (Liquefied Petroleum Gas Code). Incorrect pipe sizing can lead to appliance malfunction, soot buildup, or carbon monoxide hazards.