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Exhaust Flow Calibration for a Large-Scale Calorimetry System Using Tracer Gas Dilution



Rodney Bryant


Exhaust flow measurements are a significant source of uncertainty for measurements of heat release rate in large-scale fire experiments. Irregular flow distributions are often present in the exhaust ducts, making it difficult to measure flow accurately. Tracer gas dilution, a measurement method for volume flow, is not sensitive to flow distribution and has been applied to calibrate flow measurement devices at the exhaust ducts of a large-scale open calorimetry system. The in-line calibration reduced the bias in the exhaust flow measurement by as much as 6 %, improving the overall measurement accuracy of heat release rate. Experimental results provide evidence that the flow calibration is an improvement over the accepted practice of developing a flow correction from the comparison of oxygen consumption calorimetry with the heat output from a gas burner. The flow calibration is valid for a wide range of flow conditions and decouples the oxygen consumption calorimetry measurement from any error in determining heat release rate from the gas burner.
Fire and Materials


Tracer Gas Dilution, Flow Calibration, Heat Release Rate, Calorimetry, Flow Mixing, Exhaust Flow


Bryant, R. (2023), Exhaust Flow Calibration for a Large-Scale Calorimetry System Using Tracer Gas Dilution, Fire and Materials, [online],, (Accessed April 19, 2024)
Created October 17, 2023, Updated March 5, 2024