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How does the leak detector work?
- 2020-09-01-

The leak detector has three test types: direct test, indirect test and sealed part test. These three test methods are respectively applied to tests under pressure and vacuum conditions. The configuration is determined based on the application and must be set before the instrument is used.

Indirect/pressure rise test: The test parts are placed in the sealing cover and the HRS leak tester and the sealing cover are connected with a gas supply pipe. Apply external pressure to this part (up to 20MPa or 200bar pressure), and apply slight pressure to the sealing cover. If a part leaks, the pressure in the sealing cover will rise. This method allows certain parts to be tested under high pressure and avoids related restrictions. The HRS leak tester only tests and measures the pressure in the sealed enclosure. If there is a large leak, the pressure electronic monitoring in the sealed enclosure will cause the instrument to switch to a safe state. Direct/pressure drop test: After the pressure of the test and standard parts is charged to the required level, the HRS leak tester tests the differential pressure between the two volumes separated by the balance valve. At the end of the cycle, the HRS leak tester vents the pressure of the parts through the exhaust valve. Sealed parts test: This test is used to completely seal the parts that cannot be inflated. They are placed in a pressurized sealing cover. After closing the two valves, if the test part leaks, a pressure difference will be generated at both ends of the differential pressure sensor.

Leak detector test operation methods are divided into three categories: test method without standard parts: test the pressure change between the tested part and the sealed joint. It is not recommended to use the test without standard parts, unless it is to test the parts with very small volume; it is more objective to test the standard parts with a certain volume. There is a test method for standard parts: test the pressure change between the tested part and the standard part. The ideal test condition is: the tested part is the same as the standard part, and the tubes connected to these two parts are also the same (same length, diameter and tube type). Testing with standard parts saves time because the pressure balance time is shorter. Suitable for parts that will not deform and have similar thermal and mechanical effects. Intermediate zero test method: It is possible to test two parts at the same time using a leak detector. Connect one of the parts to the test end and the other to the standard part end, and the pressure difference sensor tests the pressure drop of one of the parts related to the other. This method is suitable for the situation where there are few defective products (generally less than 1%), and the probability of two defective products at the same time is very low; this method is also suitable for deformable parts and the temperature is different from the surrounding temperature. The fixed temperature parts. The central zero test saves time (because two parts are tested at the same time).