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

Relieve excess pressure to atmosphere as a safety device

Answer

Manually adjust system high-side pressure during operation

Answer

Prevent refrigerant backflow in the discharge piping

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

It pumps heated oil through the condenser to reject heat

Answer

It mixes oil with refrigerant vapor to improve lubrication at the compressor inlet

Answer

It heats oil in cold weather to reduce viscosity before startup

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

Fill all piping with refrigerant to pre-pressurize the system

Answer

Remove all insulation from the piping to observe for frost

Answer

Open all hand valves fully to maximize test volume

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

At the inlet of the compressor suction line

Answer

On the discharge of the cooling tower pump

Answer

At the inlet of the evaporative condenser

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 in the discharge line raises compressor head pressure excessively

Answer

Liquid accumulation in suction lines increases refrigerant velocity above safe limits

Answer

Liquid slugs cause check valves to chatter and wear out prematurely

Question 6

When isolating a section of refrigeration piping for repairs, the correct procedure is to:

Accepted Answer

Close isolation valves, relieve trapped pressure safely, verify pressure is zero, then open the line

Answer

Close the isolation valves, then immediately open flanges and cut pipe

Answer

Pressurize the isolated section with nitrogen before cutting to purge refrigerant

Answer

Remove the relief valve from the section first, then close the isolation valves

Question 7

What does pipe insulation on refrigeration suction lines primarily prevent?

Accepted Answer

Condensation and frost formation on cold surfaces, which adds heat gain and can damage supports

Answer

Heat loss from the refrigerant to the surroundings, which would lower system efficiency

Answer

Excessive vibration transmitted from the compressor through the piping

Answer

Corrosion of the pipe exterior in humid environments