The refrigeration rotary compressor is a type of rotary vane compressor, which is wide used in medium temperature (MBP) and low temperature (LBP) commercial refrigeration equipments. The commercial refrigeration equipments run on an almost continuous basis, so the reliability is the highest priority. And the refrigeration compressor is one of the most important components of the system
But even well maintained refrigeration systems will also have problems from time to time. Thus, knowing the problems and refrigeration compressor troubleshooting is critical in order to prevent series issues.
Liquid hammer is the common refrigeration problem we should be aware of.
What is Liquid Hammer?
Liquid hammer is that there is liquid refrigerant entering into the compressor at the moment of startup or during operation. As the liquid can’t be compressed, the compressor components will be damaged when the refrigerant is compressed.
The liquid hammer phenomenon can be observed with sight-glass. If there is too much liquid refrigerant in the compressor chamber, the sight-glass can be observed to be full of foam and the refrigeration compressor runs with abnormal vibration and noise after starting.
What Are The Reasons Caused Liquid Hammer?
- The return gas superheat is too small. If the superheat is too small, it will lead to incomplete gasification of the refrigerant and the gas-liquid mixture refrigerant enter into the compressor.
- Charge the Liquid Refrigerant with Improper Position. Some customers will charge the liquid refrigerant from the suction pipe for convenience, so the liquid refrigerant will enter into the refrigeration compressor directly; it will lead to compressor liquid hammer.
- Charge Too Much Refrigerant or Oil. In order to increased the system power or maintain the lubrication of the system, some customers will charge extra refrigerant or oil; if charge too much, it will cause liquid hammer when the refrigeration compressor is working.
- Do not startup at low ambient temperature for long time. Because of not startup at low ambient temperature for long time, the gaseous refrigerant in the compressor condenses into liquid refrigerant and is deposited at the bottom of the compressor. The sudden startup will cause the shaking of oil and refrigerant, causing liquid strike.
How to Prevent Liquid Hammer?
Because there is different reasons caused liquid hammer, we need to troubleshoot one by one.
Choose The Appropriate Throttle Device and Ensure Appropriate Superheat
The expansion valve port should be appropriate to ensure that the superheat is large enough and the refrigerant at the evaporator outlet can be completely vaporized.
What is the best superheat for low temperature refrigeration system and medium temperature refrigeration system?
For low temperature commercial refrigeration system, we generally suggest the superheat minimum 11K;
For medium temperature refrigeration system, we generally suggest the superheat minimum 3K~6K.
If you have more questions about the superheat, please feel free to contact with our engineers.
Charge the Refrigerant and Oil with Proper Position
The liquid refrigerant should be charged from high pressure pipe, which is between the outlet of expansion valve and inlet of the evaporator; so the newly charged liquid refrigerant will enter the compressor in a gaseous state after passing through the evaporator.
Add the Crankcase Heating Belt
The function of the crankcase heating belt is to vaporize the liquid refrigerant into gaseous refrigerant inside of the compressor.
Add a Large Accumulator
Choose a large enough accumulator, so that the liquid refrigerant can be stored in the accumulator and vaporized in the gas-liquid, and then enter into the compressor.
Please find the accumulator installation position in the refrigeration system below:
The accumulator is installed between the evaporator and suction pipe of the compressor.
The function of the accumulator is to store the refrigerant and prevent the liquid refrigerant entering into the compressor.
How to Find the High Reliable Rotary Refrigeration Compressor?
Glen refrigeration supplies rotary refrigeration compressor, which ensures your commercial refrigeration equipments with highest reliability.
Please click here Sanyo rotary refrigeration compressor for more details.
Except the fixed speed refrigeration compressor, Glen Refrigeration also supplies Sanyo variable speed refrigeration compressor with different refrigerant R404A, R410A, R290. The variable speed refrigeration compressors not only provide adequate cooling capacity for refrigerated products, they also save more energy bills.
Please click here R290 Variable Speed Refrigeration Compressor for more details.
