Theoretical background of the leakage test

In the case of a leakage test, the tightness of hollow bodies such as pumps or motors is checked. For this purpose, the so-called test piece is pressurized. If the pressure measured inside the test specimen changes, leaks occur. In the following chapters, we will inform you about the physical and technical principles of leak testing with compressed air. This knowledge is useful in understanding the overall context.

Technical overview of the leakage test at a glance

In the first chapter, we will look at the physical basics and show the relationships between pressure and leakage as well as pressure and temperature. The individual pressure descriptions and the relationship between mass flow and volume flow are also contents of the first section. The second chapter deals with leakage considerations, including the comparison of air and liquid leaks. Our online calculation aids in the third chapter support you, for example, in the determination of pressure changes or conversion. In the last section, you will find information on the actual design of test equipment, for example, important notes, which must be observed in a test machine.

Leak tester for leak testing with compressed air

A leak test can be carried out using different test methods which are suitable for different application fields. Our Leak Detector PMD02 can be used for leak testing in relative pressure and differential pressure as well as mass flow processes. The selection of the correct measurement method depends on the size of the test volume. Should you have further questions on the leakage test or the appropriate leak test method, please contact us! As an experienced leak testing machine manufacturer, we offer competent advice.

You can also find the information in the "Physical Basics" and "Leakage Considerations" on these pages in the download area as a PDF file or completely in the customer area.

Note: Please note our test conditions!


The compressed air supply should follow for all test systems in DIN ISO8573-1, the following classification:

Particle class 2 (<= 5µm)
Water class 3 (pressure dew point -20°C)
Oil class 2 (<= 0,1mg/m3)

For pollution by liquids or solid particles in the pneumatic circuits and the resulting damage to the pneumatic components and damage the pneumatic components by applying an external pressure on the test item connection no warranty or liability is accepted. This also applies for any consequential damages in test or test parts.