m3/h Gas Rate


In the simplified power output calculation, the variables and constants used are as follows:

  1. Qn: Gas flow rate in m3/h (cubic meters per hour) This represents the volume of gas flowing through the combustion system per hour. It's a measure of how much gas is being consumed in the process.
  2. ηcomb: Combustion efficiency (gross or net) This is a dimensionless value ranging from 0 to 1, which represents the efficiency of the combustion process. A higher value indicates a more efficient combustion process, where more energy from the fuel is converted into useful heat.
  3. CV: Calorific value of the gas in MJ/m3 (MegaJoules per cubic meter) This represents the amount of energy contained in a unit volume of gas. Different gases have different calorific values based on their composition. The higher the calorific value, the more energy the gas can release during combustion.
  4. 3.6: Conversion factor This factor is used to convert the energy units from MJ (MegaJoules) to kWh (kiloWatt-hours), as 1 kWh equals 3.6 MJ. The power output is usually expressed in kilowatts (kW).


Now, let's break down the simplified formula:

Power output (kW) = Qn x ηcomb x CV / 3.6

This formula calculates the power output by multiplying the gas flow rate (Qn) by the combustion efficiency (ηcomb) and the calorific value (CV). This product gives the total energy released by the combustion process in MJ/h. To convert this value to kW, we divide by the conversion factor (3.6).


In the example provided, the values were:

  • Qn = 62.34 m3/h (gas flow rate)
  • ηcomb = 0.94 (combustion efficiency)
  • CV = 39 MJ/m3 (calorific value of the gas)

By plugging these values into the formula, we get:

Power output (kW) = 62.34 x 0.94 x 39 / 3.6 = 643 kW

This result indicates that the combustion system produces approximately 643 kilowatts of power output, given the specified gas flow rate, combustion efficiency, and calorific value.

ft3/h Gas Rate

Power Output Calculation using Gas Flow Rate in ft³/h

To calculate the power output using gas flow rate in ft³/h, we first need to convert the flow rate from ft³/h to m³/h, and then use the simplified formula.

1 ft³ = 0.0283168 m³

Conversion and Calculation

First, let's convert the gas flow rate from ft³/h to m³/h:

Qn (ft³/h) = Qn (m³/h) * 0.0283168
Qn (m³/h) = Qn (ft³/h) / 0.0283168

Now, let's calculate the power output using the simplified formula:

Power output (kW) = Qn x ηcomb x CV / 3.6


  • Qn is the gas flow rate in m³/h
  • ηcomb is the combustion efficiency (gross or net)
  • CV is the calorific value of the gas in MJ/m³


For example, for a gas flow rate of 1765 ft³/h, a combustion efficiency of 0.94, and a calorific value of 39 MJ/m³, the power output would be:

  1. Convert the gas flow rate from ft³/h to m³/h: Qn (m³/h) = 1765 ft³/h / 0.0283168 = 62.34 m³/h
  2. Calculate the power output: Power output (kW) = 62.34 x 0.94 x 39 / 3.6 = 643 kW

This simplified calculation does not take into account the gas pressure and temperature but still provides an estimation of the power output of the combustion system based on the gas flow rate, combustion efficiency, and calorific value when the gas flow rate is given in ft³/h.

Flue Flow

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Burner Input

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Oil Nozzle Sizing

Nozzle Selection Example

BoilerOutput = BurnerInput / 0.91 (boiler efficiency)

BurnerInput = Kg / Hr * CV

CV = 11.8 (Gas Oil)

12.02 (Kerosene)

Kg / Hr = USGall / Hr @ 100PSI * 3.13 (Weight of 1 x US Gall = 3.13Kg)


Boiler Output: 250 kW, Fuel: Gas Oil

To calculate burner input:

250 = BurnerInput / 0.91

To calculate kg/hr:

BurnerInput = Kg / Hr * 11.8

To convert kg/hr to USGall/Hr (@ 100PSI - approx 7 bar):

Kg / Hr = USGall / Hr * 3.13

To calculate nozzle size @ 12 bar:

7.44 = 5.68 / 1.31

1.31 is the factor to convert from 100PSI to 175PSI (12 bar).

To calculate the required factor, proceed as follows:

Step Calculation
1. Required pump pressure x 14.5 = PSI (12 x 14.5 = 174)
2. PSI √ (square root) (174 √ = 13.1)
3. Divide figure by 10 = factor (13.1 / 10 = 1.31)

This ventilation calculator is for commercial and industrial applications only.

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LPG m3/h Gas Rate

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Mass Flow Rate & Power Output

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Boiler Load

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Burner Load

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NOx Conversion & Calculation

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Air Flow Needed

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Chemical Combustion Efficiency

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Nozzle Diameter

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Oil Orifice Diameter

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Air Orifice Diameter

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Gas Density

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Oil Kg To MW

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Flow Rate Converter

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Gas Pressure Temperature

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