Refrigeration Systems & Components Flashcards
7 cards from real CRST practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Refrigeration Systems & Components flashcards as text
A refrigeration system has excessively high discharge temperature. Which component failure could cause this if suction pressure is also low?
Answer: Leaking discharge valve allowing re-expansion into the cylinder
A leaking discharge valve allows hot high-pressure gas to leak back into the cylinder, which is re-compressed and creates abnormally high discharge temperatures.
What is the purpose of an equalizer line on a thermostatic expansion valve (TXV)?
Answer: Sense evaporator outlet pressure to compensate for coil pressure drop
An external equalizer line senses actual evaporator outlet pressure, allowing the TXV to accurately control superheat even when there is significant pressure drop across the coil.
Which refrigerant property determines the saturation temperature at a given pressure?
Answer: Pressure-temperature relationship unique to each refrigerant
Each refrigerant has a unique pressure-temperature (P-T) relationship; at any given pressure, the saturation temperature is fixed and can be read from a P-T chart.
A technician finds oil logged in an evaporator coil. What is the most likely contributing cause?
Answer: Insufficient refrigerant velocity to carry oil through the coil
When refrigerant velocity in the evaporator is too low, oil cannot be carried along and accumulates (logs) in the coil, reducing heat transfer.
What is the function of a head pressure control valve on an air-cooled condenser in cold ambient conditions?
Answer: Maintain minimum head pressure by flooding condenser coil with liquid refrigerant
Head pressure control valves flood condenser coils with liquid refrigerant in cold weather, reducing effective condensing area and maintaining minimum operating pressure.
Which factor most directly determines the compression ratio in a refrigeration system?
Answer: Ratio of absolute discharge pressure to absolute suction pressure
Compression ratio is calculated by dividing absolute discharge pressure by absolute suction pressure, and directly affects compressor efficiency and discharge temperature.
A refrigeration technician discovers a system running with extremely high compression ratio. What is the most likely consequence?
Answer: Excessive discharge temperature and reduced volumetric efficiency
High compression ratios cause discharge temperatures to rise sharply and reduce volumetric efficiency because re-expanded gas from clearance volume occupies more cylinder space.