1.Hydrometric method
This is the simplest and original leak detection method, which is used for bicycle tyres. It is to fill the tested work with air greater than atmospheric pressure. 1.0-3.0Mpa) Put it into the water to see if there are bubbles emerging from the workpiece. The location of bubbles is the location of leakage. The leakage rate can be estimated according to the rate of bubbles, the rate of bubbles and the size of bubbles.
2.Halogen method
Previously, common refrigerators used halide as the refrigerant. When the refrigerant was filled and sealed, the probe of the halogen leak detector was used to find the leak point outside the suspect. If the leak point was found, an audible and visual alarm would be given, and the leak point and leak rate would be relatively determined.
3．Pressure reduction method (differential pressure method)
It is to connect the inspected work to a pressure gauge using a compressor or compressed air (generally 1-3Mpa), seal it (ensure that the head does not leak) after filling it with gas, and observe the pressure drop of the pressure gauge within 24 hours. If there is a leak, the pressure will drop, but it is impossible to judge where the leak is and how much.
Of course, there are many other methods. The sensitivity of these methods generally cannot reach or can only barely reach the national standard, or they can only detect large leaks, and some cannot detect where and how many leaks.
4．Helium mass spectrometer leak detector
Its working principle is that charged ions are subject to the influence of magnetic field force in the magnetic field. According to the size of their mass charge ratio, they are separated by different deflections. It is a vacuum system and sample introduction system that ensure the normal operation of the separation and avoid collisions, which are composed of ion sources (generally generated by electron bombardment) that generate ions, magnetic fields separated by mass charge ratio, and ion receiver with amplification function that receive ions, And electrical control system. Why is it called helium mass spectrometer leak detector here? As helium naturally exists in the atmosphere in a small proportion, generally 5 ppm, small mass number means small diameter, easy to pass through gaps, easy to spread, and it is a inert gas, non-toxic, tasteless, colorless, harmless, so it is very appropriate to use it as a tracer gas and to make standard leaks.
There are many leak detection methods using helium spectrum leak detector, mainly including injection method, suction method, helium hood method and back pressure method. The vacuum chamber method in back pressure method is often used for evaporator and condenser of automobile air conditioner.