Piping Systems and Valves Flashcards
7 cards from real CARO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Piping Systems and Valves flashcards as text
A pilot-operated pressure regulating valve (PRV) in refrigeration is used to:
Answer: Automatically maintain a set downstream pressure regardless of upstream pressure changes
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.
What is the purpose of a thermosyphon oil cooler (TSOC) in relation to refrigeration piping?
Answer: It uses refrigerant liquid circulation driven by gravity and density differences to cool compressor oil without a pump
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.
What should be done to refrigeration piping before leak testing with nitrogen?
Answer: Ensure all safety valves and relief devices are isolated or removed
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.
In an ammonia refrigeration system, a 'king valve' is located:
Answer: At the outlet of the high-pressure receiver on the liquid line
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.
What is the danger of liquid slugging in a refrigerant piping system?
Answer: Liquid refrigerant entering the compressor cylinders can cause catastrophic mechanical failure
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.
When isolating a section of refrigeration piping for repairs, the correct procedure is to:
Answer: Close isolation valves, relieve trapped pressure safely, verify pressure is zero, then open the line
After closing isolation valves, any trapped refrigerant must be safely relieved and pressure verified at zero before opening piping, to prevent sudden release of pressurized refrigerant or ammonia exposure.
What does pipe insulation on refrigeration suction lines primarily prevent?
Answer: Condensation and frost formation on cold surfaces, which adds heat gain and can damage supports
Insulating cold suction lines prevents ambient heat from entering the refrigerant (increasing load) and prevents moisture from condensing and freezing on the pipe exterior, which can damage supports and insulation.