How to detect expansion valve

How to detect expansion valve: detailed explanation of methods and steps

The expansion valve is a key component in the refrigeration system, and its performance directly affects the cooling effect and energy consumption of the system. This article will introduce the detection method of the expansion valve in detail to help you quickly judge its working status.

1. Function and common faults of expansion valve

The main function of the expansion valve is to regulate the flow of refrigerant to ensure full evaporation of the refrigerant in the evaporator. Common failures include:

2. Steps to detect expansion valve

1.Visual inspection

Check the expansion valve for obvious damage, leakage or frost. Leaks usually show up as traces of oil or refrigerant.

2.stress test

Use a pressure gauge to detect the high and low pressure side pressure of the system. The normal value range is as follows:

If the pressure is abnormal, it may indicate that the expansion valve is clogged or the adjustment fails.

3.Temperature detection

Use an infrared thermometer to measure the temperature difference between the inlet and outlet of the expansion valve. During normal operation, the outlet temperature should be significantly lower than the inlet temperature.

4.Superheat test

Superheat is an important indicator for judging the working status of the expansion valve. The calculation method is as follows:

Normal superheat is 5~8℃. If it is too high or too low, the expansion valve needs to be adjusted or replaced.

3. Adjustment and replacement of expansion valve

1.Adjustment method

Adjust the superheat by changing the spring pressure by turning the adjustment screw. Turn clockwise to increase superheat, turn counterclockwise to decrease superheat.

2.Precautions for replacement

• Make sure the system has fully recovered refrigerant
• Choose an expansion valve that matches the original model
• Pay attention to cleanliness and sealing during installation

4. Frequently Asked Questions

Q: How to clean the clogged expansion valve?

A: Slight blockage can be purged with nitrogen, serious blockage requires replacement of the valve core or the entire expansion valve.

Q: What causes frost on the expansion valve?

A: It may be caused by insufficient refrigerant, clogged filter or excessive expansion valve opening.

5. Summary

The detection of the expansion valve requires a combination of pressure, temperature, superheat and other data. Regular maintenance and correct adjustments can extend its service life and ensure efficient operation of the refrigeration system. If the fault cannot be eliminated, it is recommended to contact professional technicians.