Visual leak detection:  

When oil is found somewhere in the system, it may be a leakage point.  

Visual leak detection is simple and easy, no cost, but there are great defects, unless the system suddenly broke the big leak point, and the system leakage is liquid colored media, otherwise visual leak detection can not locate.  

Soap water leak detection:  

Fill the system with 10-20kg/cm2 pressure nitrogen, and then apply soapy water to all parts of the system, and the bubbled place is the leakage point.  This method is the most common leak detection method in roadside repair factories at present, but the human arm is limited, the range of human vision is limited, and most of the time, we can not see the leakage point.  

Nitrogen water leak detection:  

Fill the system with 10-20kg/cm2 pressure nitrogen, immerse the system in water, the bubble is the leakage point.  Soapy water leak detection in front of this method and the essence, while the cost is low, but there are obvious disadvantages: leak detection with moisture is easy to enter the system, lead to the system of material from corrosion, high pressure gas at the same time also is likely to cause more damage to system, carries on the leak detection when the intensity of labor is big, thus make the maintenance costs. 

Halogen lamp leak detection:  

Light the leak detection lamp, hold the halogen lamp on the air tube, when the mouth of the tube near the leakage of the system, the flame color turns purple blue, that is, there is a lot of leakage.  In this way, open flame is produced, which is not only dangerous, but also harmful gas will be produced when open flame and refrigerant are combined. In addition, it is not easy to accurately locate the leakage point.  So this approach is hardly used now, and if you can see it, it's probably in the uncivilized stage.  

Gas differential pressure leak detection:  

Using the pressure difference inside and outside the system, the pressure difference is amplified by the sensor, and the leak detection results are expressed in the form of digital or acoustic or electronic signals.  This method can only "qualitative" to know whether the system leakage and can not accurately find the leakage point.