- With reference to refrigeration plants, describe the effects of EACH of the following, stating remedial actions to be taken in EACH case:
(a) undercharge of refrigerant;(3)
(b) air in the system;(3)
water or moisture in the system.(4)
Refrigeration Plant Faults
(a) Undercharge of refrigerant (3 marks)
- Effects:
- Evaporator not fully flooded → poor cooling capacity.
- Low suction pressure and possible compressor overheating.
- Remedial action:
- Leak test system to locate and repair leaks.
- Recharge system with the correct amount of refrigerant.
(b) Air in the system (3 marks)
- Effects:
- Non-condensables accumulate in condenser → higher condenser pressure and temperatures.
- Reduced efficiency and risk of compressor overload.
- Remedial action:
- Purge air from the condenser top using a refrigerant purging device or manual vent (into a recovery unit, not atmosphere).
(c) Water or moisture in the system (4 marks)
- Effects:
- Ice formation at the expansion valve → blockage of refrigerant flow.
- Corrosion inside the system and deterioration of compressor oil.
- Remedial action:
- Locate and eliminate source of water ingress.
- Fit/renew dehydrator or drier filters.
- If severe, pump down system, evacuate with a vacuum pump, and recharge with dry refrigerant.