Helium mass spectrometry leak detection method The helium partial pressure measurement principle of helium mass spectrometry leak detector is used to measure the helium leakage amount of specimen. If there is a leak in the sealing surface of the part under test, it indicates that the leaking helium and other gases have been discharged from the leak. After the leakage gas enters the leakage detector of the helium mass spectrometer, only the helium partial pressure signal value in the gas is displayed due to its selective detection ability. On the basis of obtaining the helium signal value, the amount of helium leakage from the leak hole can be obtained by comparing the standard leak hole. Helium mass spectrometry leak detection methods can be divided into vacuum method, overpressure method, vacuum pressure method and back pressure method according to the different relationship between the leakage gas location shown in the process of leak detection and the measured object. The principles of these four helium mass spectrometry leak detection methods are reviewed. Advantages and disadvantages and test criteria.

Leakage detection by vacuum mass spectrometry.

If a leak is detected using a vacuum method, the internal seal chamber of the test product should be vacuum treated using an auxiliary vacuum pump or leak detector and helium gas should be applied to the outer surface of the test product by helium cap or spray method. If there is a leak hole on the surface of the product under test, helium gas enters the product under test through the leak hole and then enters the helium mass spectrometer leak detector to realize the leakage measurement of the product under test. According to different leakage methods, the vacuum process can be divided into vacuum injection method and vacuum helium cap method.

Vacuum spraying method: Helium is sprayed on the outer surface of the tested product with a spray gun, which can realize accurate positioning of leakage;

Vacuum helium cap method: Cover all tested products with a helium cap with a specific sealing function, fill it with a certain helium concentration, and measure the total leakage rate of tested products.