Class 4 (4th Engineer) MEKG 📅 Oct 2022

Exam Question

With reference to air compressor state why

(a) Piston rings freeness and condition is important. (4)

(b) Correct clearance volume is critical to performance. (4)

(d) A suction filter should be of large size and kept clean (4)

Reference Answer

### (a) Importance of Piston Ring Freeness and Condition (4 Marks)
Piston rings are critical components for the efficient and safe operation of a reciprocating air compressor. Their freeness (ability to move within the piston grooves) and overall condition are paramount for the following reasons:
1. **Sealing and Compression:** The primary function of compression rings is to form a dynamic gas-tight seal between the piston and the cylinder liner. This prevents the leakage of high-pressure air from the combustion space into the crankcase (a phenomenon known as 'blow-by').
* **Good Condition:** Ensures maximum compression is achieved, leading to higher volumetric efficiency and the designed Free Air Delivery (FAD).

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