Practice Test Geeks(CRST) Certified Refrigeration Service Technician Practice Test
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CRST Refrigerants & Thermodynamics Flashcards

6 cards from real CRST practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. What refrigerant is classified as R-717 and widely used in large industrial refrigeration systems?

    Answer: Ammonia (NH3)

    R-717 is ammonia (NH3), a natural refrigerant with excellent thermodynamic properties and zero ODP/GWP widely used in industrial cold storage and food processing.

  2. What is the correct method for determining the saturation temperature of a refrigerant at a known pressure?

    Answer: Consult the refrigerant pressure-temperature (PT) chart for that specific refrigerant

    Each refrigerant has a unique pressure-temperature relationship — technicians use the PT chart specific to that refrigerant to determine saturation temperature at any measured pressure.

  3. What does the term 'latent heat of vaporization' mean in refrigeration?

    Answer: The heat absorbed or released when a substance changes between liquid and vapor at constant temperature and pressure

    Latent heat of vaporization is the energy absorbed or released during phase change (liquid↔vapor) without any temperature change, and it is the primary mechanism of heat transfer in refrigeration.

  4. Which refrigerant blend is commonly used as a drop-in service replacement for R-22 in low-temperature commercial refrigeration applications?

    Answer: R-422D

    R-422D is an HFC blend approved as a near-drop-in retrofit for R-22 systems, particularly in low- and medium-temperature applications with compatible lubricant.

  5. What is the purpose of a filter-drier installed in the liquid line of a refrigeration system?

    Answer: Remove moisture and solid contaminants from the refrigerant to protect the expansion valve and compressor

    A liquid line filter-drier uses desiccant material to absorb moisture and a mesh filter to trap solid particles, preventing ice formation at the expansion device and acid formation in the system.

  6. What is the refrigerant charge method used when a manufacturer specifies charging by weight?

    Answer: Use a refrigerant scale to add the exact specified weight of refrigerant to the system

    When charging by weight, a refrigerant scale is used to measure and add the exact factory-specified charge weight, which is the most accurate method for sealed system charging.