The mass point leak rate technique is often the methodology of choice for quantifying
leak rates as it uses simple elementary measurements, applies to gas systems of low
mass, proves effective for low leak rates, and does not rely on test-gas conversions.
In this methodology, a number of instantaneous mass measurements are calculated
through samples of volume, pressure, gas composition, and temperature measurements
over time. A regression analysis of the corresponding mass-time sample set yields
the leak rate of the system. A detailed uncertainty analysis is paramount for a
complete, experimental characterization of the leak rate and previously was not
fully implemented in the mass point leak rate method. Recent advancements in
regression uncertainty analysis by propagation of errors afford the ability to quantify
the uncertainty with estimates of covariance in the regression results. The mass point
leak rate technique with the associated detailed measurement uncertainty analysis
offers the ability to quantify both the leak rate and the uncertainty associated with
the leak rate value. Detailed herein is the development of the methodology and
a detailed uncertainty analysis that includes both precision (repeatability) and bias
(systematic) error. Alternative leak rate methods are also discussed for comparison
purposes. An example in the methodology is presented.
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