Abstract: A method of continually monitoring the heating value of a fuel gas, and the apparatus for carrying out this method. The method includes mixing a fuel gas of known heating value with a combustion-supporting gas, putting the mixture through a combustibility meter, adjusting the mixture to 100% or some fixed portion thereof of the lower explosive limit of the combustible gas, substituting a fuel gas of unknown heating value without changing the air to gas ratio and using the percent LEL now indicated by the combustibility meter to calculate the heating value of the unknown fuel gas. The apparatus for carrying out this method includes a combustibility meter (10) having a sensing transducer (12), a source of certified known fuel gas (30), a source of unknown sample fuel gas, a mixing system (14) for mixing these gases with air in controllable ratios, and an instrument (28) for recording the heating value of the unknown fuel gas.

Abstract: A combustible fuel gas burner has a primary tube supplying gas and primary air to a main burner, a secondary tube supplying secondary air to the main burner to afford complete combustion, and an exhaust tube through which the products of combustion are exhausted. The exhaust tube also acts as a flash-tube for igniting the main burner. In the absence of combustion, the gas and primary air issuing from the primary tube and the secondary air issuing from the secondary tube combine to form an air-gas mixture in the exhaust tube which is too lean (below the lower limit of flammability) to be ignitable. The supply of secondary air is controlled so as to vary the air-gas ratio in the exhaust tube such that this ratio changes through a spectrum of values between the lower and upper limits of flammability wherein the flame propagation speed of the mixture is substantially greater than the flow velocity thereof.