CARO - Certified Assistant Refrigeration Operator Compressor Operation and Maintenance Questions and Answers

Question 1

An operator notices excessive vibration and a new, unusual noise coming from a reciprocating compressor during operation. Which of the following is the most likely immediate cause for this issue?

Accepted Answer

Slugging of liquid refrigerant

Answer

Clogged oil filter

Answer

Incorrect oil viscosity

Answer

Loose mounting bolts

Question 2

During a routine maintenance check on a screw compressor used in an ammonia refrigeration system, an operator finds that the oil in the separator is milky and foamy. What is the most probable cause of this condition?

Accepted Answer

The oil is contaminated with moisture/water.

Answer

The compressor has been running unloaded for too long.

Answer

The oil filter is completely bypassed.

Answer

Non-condensable gases are present in the system.

Question 3

Which of the following routine maintenance tasks is most critical for ensuring the long-term health and efficiency of a reciprocating compressor's moving parts?

Accepted Answer

Regularly checking and changing the crankcase oil and filters

Answer

Calibrating pressure gauges annually

Answer

Wiping down the compressor housing weekly

Answer

Repainting corroded exterior surfaces

Question 4

An operator needs to perform maintenance that requires opening up a compressor to the atmosphere. What is the critical first step in the pump-down procedure before any components are loosened?

Accepted Answer

Slowly throttle the suction stop valve to lower crankcase pressure.

Answer

Close the suction and discharge service valves.

Answer

Disconnect the main power supply using lockout/tagout procedures.

Answer

Attach a gauge manifold to the service ports.

Question 5

A screw compressor is consistently tripping on its high-temperature safety cutout. The condenser appears to be operating normally, and the refrigerant charge is correct. Which of the following maintenance issues is the most likely cause?

Accepted Answer

A dirty or clogged oil cooler/filter

Answer

A malfunctioning capacity slide valve

Answer

Excessive non-condensable gases

Answer

A partially closed suction service valve

Question 6

What is the primary purpose of an oil separator in an industrial refrigeration system?

Accepted Answer

To remove entrained oil from the discharge gas and return it to the compressor.

Answer

To filter out metal particles from the compressor oil.

Answer

To remove liquid refrigerant that has mixed with the oil.

Answer

To cool the oil before it is reinjected into the compressor.

An operator notices excessive vibration and a new, unusual noise coming from a reciprocating compressor during operation.Which of the following is the most likely immediate cause for this issue?

An operator notices excessive vibration and a new, unusual noise coming from a reciprocating compressor during operation.
Which of the following is the most likely immediate cause for this issue?