Routine Leak Detection and Reverse Diffusion Leak Detection
There are two ways of leak detection in helium mass spectrometer, one is conventional leak detection, the other is reverse diffusion leak detection. The principle of inverse diffusion is shown in the figure. The reverse diffusion leak detection is to connect the tested piece to one end of the outlet of the molecular pump, and the leaked helium enters the mass spectrometer tube installed in the air inlet end of the pump from the outlet of the molecular pump against the exhaust direction of the pump and is detected.
This leak detection method is based on the different compression ratio (the ratio of the pressure at the outlet of the molecular pump to the pressure at the inlet) of the molecular pump for different mass of gas, that is to say, it is designed with different degrees of reverse diffusion of different gases.The reverse diffusion leak detection method allows high internal pressure of the inspected parts. The sfj-231 / 241 helium mass spectrometer leak detector can reach 1000Pa (generally, the conventional leak detector is below 0.05pa). It is suitable for the detection of large containers or devices with large leakage, and it is also suitable for the detection of suction gun leak. The reverse diffusion method also has the advantages of not easy to be polluted and long filament life.
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