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How Pressure Decay and Leak Rate are Related

Using pressure decay leak detection testing instruments is an industry norm for leak testing parts that have relatively small volumes. The component to be tested is pressurized with air and the pressure transducer in the leak tester measures pressure changes. A drop in pressure indicates a leak in the component. Most pressure decay panels measure pressure changes in mbar, Pascal, mbar/sec or Pascal/sec. This presents a challenge because leak specifications are usually specified in volumetric units such as cc/sec or cc/min. Relationship between Pressure Decay and Leak RateIn this Application Note, I will provide a solution to easily convert pressure decay readings into volumetric leak rates. I will assume that the total test volume of the part to be tested is known. This is typically available after a test system is designed and built. It is also necessary to take into consideration the total test volume that includes the test part, the test connection pipe and the internal volume of the test unit. The relationship between pressure drop, leak rate and volume is derived from the basic gas law and is as follows: – Download our Application Note, “The Relationship between Pressure Decay and Leak Rate” for full details. Download App Note »

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David Selin

Managing Director at Uson Ltd.

Comments (2)

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    0.2CC/Min is equal to how many Kpa??


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    not possible to download and receive the app note ” relationship between pressure decay and leak rate “


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