Leak-Testing at Very Low Test Pressures

A large number of leak tests with compressed air are performed at pressures ranging from 100 mbar to 10 bar and even higher, depending on the type of application.

Occasionally, we are faced with industrial applications requiring a very low test pressure. This is coupled with the necessity to combine positive and negative gauge pressures.

The implementation of a flexible low pressure regulation in both positive and negative gauge pressure ranges is a great technical challenge. Accordingly, there are no standard devices for low pressure testing on the market.

The well-established CETATEST 815 series of differential pressure leak testers has now been extended to include a low-pressure test device specially designed for these applications.

The solution developed for pressure ranges between ±5 mbar and ±50 mbar requires the use of a suitable electronic pressure controller as well as various modifications and optimizations.

The leak tester CETATEST 815 Low Pressure with a pressure range of ±5 mbar has proved very successful for the testing of lamps used in potentially explosive atmosphere. In this case, the lamps must be tested for vapor-tightness at a very low negative pressure of -3 mbar.

The documented results of 603 repeated measurements with a test part volume of several liters and target filling pressure of -3.00 mbar show the excellent repeatability of the device. In 455 cases, the filling pressure lay between -2.99 mbar and -3.01 mbar. This represents 75.6 % of all measurements. An absolute deviation of 0.01 mbar from the target filling pressure of -3.00 mbar corresponds to 0.3 % only of the target value. Only 16 measurements (equivalent to 2.7 % of the total number of measurements) showed larger deviations from the target pressure, but not exceeding 0.05 mbar. The results with positive gauge pressure are equally impressive.

This technical solution has also been extended to the pressure range of ±50 mbar. This increases the available pressure ranges of the CETATEST 815 devices by two additional pressure ranges: ±5 mbar and ±50 mbar. The user enjoys utmost flexibility thanks to the electronic pressure controller.

CETA Testsysteme GmbH will exhibit at the Control 2017 trade fair (09-12/05/2017, Stuttgart) in hall 4, stand 4131.