Class 4 (4th Engineer) MEKG 📅 Oct 2023

Exam Question

With reference to main refrigeration plants give reason for each of the following operational irregularities and state how these are dealt with:

(а) Rapid loss of lubricating oil from the crankcase of a " vee " block compressor (4)

(b) Steady "fall off" in refrigeration effect over a comparatively short period of time (4)

(d) Short cycling (4)

Reference Answer

### (a) Rapid loss of lubricating oil from the crankcase of a "vee" block compressor
**Reason:**
Rapid loss of lubricating oil from the crankcase is primarily due to oil carryover into the refrigerant circuit. This is undesirable as it fouls heat exchanger surfaces, reducing efficiency, and can lead to compressor seizure due to lack of lubrication.
* **Worn Internal Components:** Worn piston rings, cylinder liners, or seals allow lubricating oil from the crankcase to be scraped up and carried past the piston into the compression chamber. This oil then becomes entrained in the high-pressure refrigerant gas and discharged from the compressor.

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