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Sunday, March 15, 2009

refrigeration compressor,mycom N62WB,N8WB,N62WA,N4WA,N2WA,N6WA,N42WA,N8WA,N4WB,N6WB,N42WB,N12WB,N124WB,grassoRC2112,RC4212,RC6312,RC8412,sabroe,bitzer

Trouble shooting for refrigeration compressor, mycom,grasso,sabroe,bitzer,carrier,Copeland.

Abnormal pressure in the refrigeration system may damage the refrigeration compressor. At excepcionally high pressure various parts of the plant may explode.
A. Abnormally high pressure
High pressure may be due to :
- parts of the plant being heated externally,e.g.during defrosting or because of higher ambient temperatures (as a consequence of fire,heat radiation from sun or other sourches of heat)
- Expansion of liquid in closed vessel, due to an increase in temperature.
- Or with liquid pumps,the flow of liquid may be restricted e.g by a blockage in the pipe line,clogged filter or overcharging of a vessel
B. Excessive discharge pressure
Excepcionally high discharge pressure may be due to :
- poor condenser cooling e.g.due to failure in the cooling water,blockedfan/cooling water pump,impurities,chalk deposits or deposits on the surfacewhich conduct heat.
- The presence of gases (especially air) in the condenser which cannot be condensed.
- Excessive refrigerant charge.
Remedy :
- Regulate the water/air supply or, if necessary reduce the compressor capacity.
- Purge the air from the condenser.
- The refrigerant fills the condenser,reducing its effective area.
C. Low discharge pressure
Reducing the discharge pressure cause the volumetric efficiency of the refrigeration plant to increase,or increases the compressor capacity and reduces the compressor energy consumption.
However,it is often necessary to avoid low discharge temperatures.Low discharge pressure can increase the cooling water consumption to an unreasonable level, and result in operational problems due to insufficient pressure in the liquid line. A low discharge pressure will reduce the pressur drop through the expansion valves in the plant, or cause vapour to form ,which in turn means that the valves may not be able to supply the evaporators with a sufficient amount of refrigerant to meet the refrigeration requirements.
D. Insufficient discharge pressure
- Compresor short of capacity
- Defective or leaky pressure valves.
- Excessive compressor capacity.
- Bypass between the high pressure and suction side of the compressor.
- Defective piston rings or worn cylinder.
Remedy :
- Check the compressor capacity corresponds to the plant load.
- Check valve plates and piston rings,replace the worn parts.

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