CARO Piping Systems and Valves 3

Question 1

A pilot-operated pressure regulating valve (PRV) in refrigeration is used to:

Accepted Answer

Automatically maintain a set downstream pressure regardless of upstream pressure changes

Answer

A pilot-operated pressure regulating valve uses a small pilot valve to sense downstream pressure and modulate the main valve to maintain a constant set pressure, enabling precise automatic pressure control.

Question 2

What is the purpose of a thermosyphon oil cooler (TSOC) in relation to refrigeration piping?

Accepted Answer

It uses refrigerant liquid circulation driven by gravity and density differences to cool compressor oil without a pump

Answer

A thermosyphon oil cooler circulates refrigerant by natural convection (density difference between warm and cool liquid) through an oil cooler to reject heat from compressor oil without a mechanical pump.

Question 3

What should be done to refrigeration piping before leak testing with nitrogen?

Accepted Answer

Ensure all safety valves and relief devices are isolated or removed

Answer

Before pressure testing, safety relief valves must be isolated or removed so they do not open during the test and release nitrogen, which could give a false indication of passing.

Question 4

In an ammonia refrigeration system, a 'king valve' is located:

Accepted Answer

At the outlet of the high-pressure receiver on the liquid line

Answer

The king valve is the main liquid shutoff valve located at the outlet of the high-pressure receiver, allowing the system liquid charge to be isolated in the receiver for service or pump-down operations.

Question 5

What is the danger of liquid slugging in a refrigerant piping system?

Accepted Answer

Liquid refrigerant entering the compressor cylinders can cause catastrophic mechanical failure

Answer

Liquid refrigerant is incompressible, so if it enters a reciprocating compressor cylinder it can hydraulically fracture valve plates, break connecting rods, or destroy the compressor.

CARO - Certified Assistant Refrigeration Operator Practice Test

CARO - Certified Assistant Refrigeration Operator Practice Test

CARO Piping Systems and Valves 3