One of the classic methods used in leak measuring is, of course, pressure decay. In this tutorial we will go through the theory and steps for measuring leaks using pressure decay methods. You can also download the entire course in PDF format and more detail here on the last page of this tutorial. 

Part 1 – Pressure decay testing – how it works

Pressure decay is probably the most widely used method of leak testing in manufacturing production lines. The process is uncomplicated, relatively inexpensive and easily automated.

Air is simply injected into a test object, after which the pressure source is valved off. Any decrease in air pressure over time signifies a leak.

For pressure decay, sensitivity is a function of the object’s size and the time interval of the test. Medium and large objects require a longer cycle time to achieve an adequate level of sensitivity for most applications. For medium-size objects, sensitivity is limited to the detection of leaks emitting 0.5 – 1.0 cc/min.