CARO Compressor Operations and Maintenance 5

Question 1

A compressor's high-pressure cutout trips repeatedly. Which condition is the most likely cause?

Accepted Answer

Non-condensable gases or loss of condenser water/air flow

Answer

Non-condensables or poor condenser heat rejection raise head pressure until the high-pressure cutout opens.

Question 2

What is the function of the oil pressure safety (oil failure) switch on a compressor?

Accepted Answer

Stops the compressor if net oil pressure does not reach a safe level within a set time delay

Answer

The oil failure switch shuts down the compressor when net oil pressure stays below its setpoint beyond the time delay.

Question 3

Why does an oil failure switch include a time delay, often around 90-120 seconds?

Accepted Answer

To allow oil pressure to build during startup without nuisance trips

Answer

The delay gives the oil pump time to build pressure at startup so the compressor is not shut down needlessly.

Question 4

What happens if a compressor short-cycles frequently?

Accepted Answer

Increased motor and contactor wear, poor oil return, and higher energy use

Answer

Frequent starts stress motors and contactors and may not allow enough run time to return oil properly.

Question 5

What is the purpose of the suction strainer installed at a compressor inlet?

Accepted Answer

To trap scale, dirt, and debris before they enter the compressor

Answer

The suction strainer catches solid debris that could damage valves, pistons, or rotors.

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