Signs of normal operation of refrigeration system and causes of common failures

Signs of normal operation of refrigeration system：

1.The compressor should run smoothly without any noise after starting, and the protection and control components should work normally.

2.Cooling water and refrigerant water should be sufficient

3.The oil will not foam much, the oil level is not less than 1/3 of the oil mirror.

4.For the system with automatic oil return device, the automatic oil return pipe should be hot and cold alternately, and the temperature of the liquid pipe filter before and after should have no obvious difference.For a system with a reservoir, the refrigerant level shall not be lower than 1/3 of this level indicator.

5.Cylinder wall should not have local heating and frosting.For air conditioning products, suction pipe should not have frosting phenomenon.For refrigerated products: suction pipe frosting generally to the suction valve mouth is normal.

6.In operation, the feeling of hand touch horizontal condenser should be upper part hot and lower part cool,The junction of cold and heat is the interface of refrigerant.

7.There should be no leakage or oil seepage in the system, and the pointer of each pressure gauge should be relatively stable.

Common failures of refrigeration systems:

1.Excessive exhaust pressure

Cause of failure:

Air and other non-condensable gases in the system;

Cooling water is Insufficient or too hot;

Dirty condenser, affecting heat transfer;

Too much refrigerant in the system;

The exhaust valve is not fully opened or the exhaust pipe is not clear.

Solution:

Release air and other non-condensable gases;

Adjust the cooling water, reduce the water temperature;

Clean condenser water path;Recovery of excess refrigerant;

Full exhaust valve, dredge exhaust pipe.

·Hazards of excessive refrigerant:

Excessive refrigerant will occupy part of the condenser volume, reducing the heat transfer area, resulting in high condensation temperature and pressure;

The evaporation temperature of the refrigeration system increases, the evaporation pressure increases, and the refrigeration effect decreases.

Inspiratory pressure is too high;

Excessive refrigerant, refrigerant liquid into the compressor, causing wet compression, or even liquid hammer;

Increase the starting load, the motor is difficult to start.

2.Too low exhaust pressure

Cause of failure:

The cooling water temperature is too low or the water quantity is too large;

Compressor exhaust valve blade damage or exhaust pipe leakage;

Insufficient cooling dose in the system;

Improper adjustment of energy regulating mechanism;

Safety valve opens too early, high and low pressure bypass;

Solution:

Adjust water supply;

Check the exhaust valve and exhaust pipe;

Supplement refrigerant;

Adjust the adjustable mechanism to make it normal;

Adjust the opening pressure of the safety valve;

3. Excessive inspiratory pressure

Cause of failure:

Excessive opening of expansion valve;

The expansion valve has a problem or the position of the temperature sensing bag is not correct;

Excessive cooling dose in the system;

Excessive heat load;

High and low pressure gas channeling is broken;

Safety valve opens too early, high and low pressure bypass;

Solution:

Correct adjustment of expansion valve opening;

Check the expansion valve to adjust the position of the temperature sensing drum;

Recovery of excess refrigerant;

Try to reduce the heat load;

Check valve sheet and cause of gas channeling;

Adjust the opening pressure of the safety valve;

4. Low inspiratory pressure

Cause of failure:

Small opening or damage of expansion valve;

Blockage of suction line or filter;

Heat bag leakage;

Insufficient system cooling dose;

Too much oil in the system;

Evaporator dirty or frost layer is too thick;

Solution:

Open the large expansion valve to the appropriate position, or replace;

Check suction pipe and filter;

Replace the heating bag;

Supplementary refrigerant;

Overhaul oil separator to recover excess oil;

Cleaning and defrosting;

5, exhaust temperature is too high

Cause of failure:

Too much superheat in the inhaled gas;

Low suction pressure, large compression ratio;

Exhaust valve disc leakage or spring damage;

Abnormal wear of compressor;

Oil temperature is too high;

Safety valve opens too early, high and low pressure bypass;

Solution:

Properly adjust the expansion valve to reduce the superheat;

Increase the suction pressure, reduce the compression ratio;

Check and replace the exhaust valve disc and spring;

Check the compressor;

Adjust the opening pressure of the safety valve;

Lowering oil temperature;

6. Excessive oil temperature

Cause of failure:

The cooling effect of oil cooler decreases.

Insufficient water supply for oil cooling;

Abnormal wear of compressor;

Solution:

Oil cooler dirty, need cleaning;

Increase water supply;

Check the compressor;

7. Low oil pressure

Cause of failure:

The oil pressure gauge is damaged or the pipeline is blocked;

Too little oil in the crankcase;

Improper adjustment of oil pressure regulating valve;

Too much refrigerant dissolved in the lubricating oil in the crankcase;

Too large clearance of oil pump gear;

The suction pipe is not smooth or the filter is blocked;

Freon gas in oil pump;

Solution:

Change the oil pressure gauge or blow through the pipeline;

Add lubricating oil;

Correct adjustment of oil pressure regulating valve;

Close the opening of the expansion valve;

Replace or repair gear clearance;

Blow through the suction pipe and clean the filter;

Fill the pump with oil to degass the gas.

8. High oil pressure

Cause of failure:

The oil pressure gauge is damaged or the value is incorrect;

Improper adjustment of oil pressure regulating valve;

Blockage of oil discharge pipeline;

Solution:

Change oil pressure gauge;

Correct adjustment of oil pressure regulating valve;

Blow through the drain line.