LPG Flow and Heat Power Calculator

LPG composition

Select volume or mass percent composition

Volume fraction %vol

Ratio of propane or butane volume to the total volume of the mixture

Mass fraction %wt

Ratio of propane or butane mass to the total mass of the mixture

Description

q liq - volume flow rate of the liquid phase

LPG flow when it is in the liquid phase, before the evaporator

q gas - volume flow rate of the gas phase at normal conditions

LPG flow when it is in the gas phase, after the evaporator

V liq - velocity of the liquid phase

The velocity of LPG when it is in a liquid phase before it evaporates

V gas - velocity of the gas phase

The velocity of LPG when it is in the gas phase, after the evaporator

D liq - pipe diameter of the liquid phase

Internal pipe diameter of the LPG line liquid phase before the evaporator

D gas - pipe diameter of the gas phase

Internal pipe diameter of the LPG line gas phase after the evaporator

ṁ - mass flow rate

LPG flow rate in terms of mass flow in the unit of time. Conserved between liquid and gas phase of LPG

P - combustion heat power

Heat power generated after the combustion of LPG. Actual heat power should be reduced for the efficiency loses

LHV_G - lower heating value - mass

The heating value of LPG mixture - energy released during the combustion of a unit of mass

p - absolute pressure of LPG gas

The pressure of the LPG after the evaporator or after the pressure control valve

T - gas temperature

The temperature needed to calculate LPG density after the evaporator or after the pressure control valve

ρ gas - gas actual density

Calculated density for entered pressure and temperature, and mixture components ratio

ρ gas_nor - gas density at normal conditions

A density of LPG mixture at normal conditions p=101325 Pa and t=0⁰C

M -molar mass

Calculated molar mass for the selected ratio of propane and butane in the LPG mixture

Calculation setup

Select value to calculate. You should enter not selected one.

P

combustion heat power calculation

q liq/q gas/ṁ

LPG flow rate calculation

Select value to input. You should enter selected one. The other two will be calculated

ṁ

mass flow rate

q liq

liquid phase flow rate

q gas

gas phase flow rate

Select value to input. You should enter selected one. The other one will be calculated. Available only if the gas is selected fluid

V liq

liquid phase velocity

D liq

liquid phase pipeline diameter

Select value to input. You should enter selected one. The other one will be calculated. Available only if the gas is selected fluid

V gas

gas phase velocity

D gas

gas phase pipeline diameter

Why Use This LPG Flow and Heat Power Calculator?

This calculator is a practical tool for estimating the flow rate, pipe diameter, and heat power of liquefied petroleum gas (LPG). LPG is a hydrocarbon fuel composed mainly of propane, butane, and their mixtures. For example, you can use this tool to determine the required LPG flow rate for a gas furnace burner based on the desired heat output.

How the Calculation Works?

The calculator supports flow and heat power calculations for both liquid and gaseous phases of LPG. It can also be used for pure propane or butane flow calculations.

In gas form, propane and butane are compressible, but this tool assumes incompressibility, which is accurate only for the liquid phase of LPG. The calculator computes key physical properties—such as mixture density and partial pressures—based on your selected propane–butane ratio.

You can also use the calculator to determine the required pipe diameter for a given flow rate. Flow rate inputs can be entered as mass flow rate, liquid volume flow rate, or gas volume flow rate at standard conditions.

It also provides convenient unit conversion between mass and volume flow rates, for both liquid and gas. The standard conditions for gas phase flow rate are:

• Pressure: 101,325 Pa (1 atm)
• Temperature: 273.15 K (0°C)

When Should You Not Use This Calculator?

This tool does not calculate pressure drop in a pipeline. If you need to estimate pressure loss, please use a dedicated liquid or gas pressure drop calculator.