Abstract: A method and apparatus for determining the calorific value of a first combustible gas involves mixing the first combustible gas with a second combustible gas having a known calorific value and with a combustion supporting gas and burning the resulting mixture, detecting a property of the burning mixture indicative of whether the burning occurred at the stoichiometric point, adjusting the relative flow rates of the first and second combustible gases and the combustion supporting gas so that said burning occurs substantially at the stoichiometric point or at a selected offset from that point, and ascertaining the volume ratios of the gases at the adjusted flow rate to produce a value proportional to the overall calorific value of the mixture of the first and second combustible gases. Based on the foregoing, the contribution to the overall calorific value made by the second combustible gas having a known calorific value can be deleted to yield the calorific value of the first combustible gas.

Abstract: A gas calorimeter and method of measuring the calorific value of fuel gases in which a fixed volume of gas to be measured is burned in a controlled environment. The temperature increase of the air in the environment caused by the burning is used to determine the calorific value of the gas. The gas to be measured is intermittently supplied to the controlled environment using a base plate which has portions defining a plurality of dispersion holes in a distributed manner so that a greater number of the plurality of dispersion holes are in and around the periphery of the base plate than are in and toward the center of the base plate.

Abstract: Gas is vented through a very small orifice or pore with substantially stable pressures before and after the orifice. The orifice is designed so that the expansion through it is similar to a Joule-Thompson expansion of the gas. With ideal gas, this occurs isothermally. The flow through this orifice is determined for a selected pressure drop across it and the square of this flow is inversely proportional to the relative density. With real gases there is a slight error introduced due to a supercompressibility of the gas, but this is offset by an error in the opposite direction believed to be due to the Joule-Thompson cooling of the gas as it passes through the orifice. Substantially exact error cancellation is obtained within a preferred operating range of the pressure drop across the orifice for a given orifice diameter.

Abstract: The flowrate of a compressible gs is determined by measuring the pressure and temperature on each side of a flow impedance device, such as an orifice plate and computing the flowrate from the resulting pressure and temperature differentials according to a newly discovered orifice equation disclosed herein. The flowrate determined in accordance with the invention is more accurate than that calculated by using the standard orifice equation, which ignores the temperature differential. In addition, the calculation is independent of the type of flow impedance used and is not affected by degradation of the impedance device, such as the erosion of the orifice in orifice plates.