Comparison of two flow measurement devices for use in fire experiments.

Bi-directional probes are utilized throughout fire science to measure fire-induced flows due to their ability to measure flow which changes direction, and to withstand hostile environments. However, they are not available commercially and researchers must take it upon themselves to make and manufacture them. S-type pitot probes (S-probes) work on the same principle as bi-directional probes, measuring the differential pressure between two openings, thereby offering the same benefits.

Exhaust flow calibration for a large-scale calorimetry system using tracer gas dilution.

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 (TGD), 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.

Improving the State-of-the-Art in Flow Measurements for Large-Scale Oxygen Consumption Calorimetry.

The accuracy of the exhaust flow measurement contributes significantly to the uncertainty of calorimetry measurements for large fire testing. Less than ideal flow characteristics such as skewed velocity distributions are typical of these large-scale flows and make it difficult to achieve the desired measurement accuracy. Consensus standards for fire testing recommend either bi-directional probes or orifice plates to determine exhaust flow.

Uncertainty estimates of tracer gas dilution flow measurements in large-scale exhaust ducts.

Accurate measurements of volume or mass flow in large conduits can be difficult to achieve due to non-ideal flow characteristics such as asymmetry of the velocity profile and off-axis flow components due to swirl. The tracer gas dilution method is independent of these and other non-ideal flow characteristics, but relies on the conservation and uniform mixing of the tracer. This study demonstrates the application of the tracer gas dilution method to measure the volume flow in a large-scale exhaust duct used for flue gas venting.