What is the state of the refrigerant as it exits the metering device?

• A. High pressure liquid
• B. Low pressure vapor
• C. High pressure vapor
• D. Low pressure liquid

Answer: (D)

The metering device throttles the refrigerant, dropping its pressure from the condenser pressure down to the evaporator pressure and cooling it as it expands. Because the goal is to feed the evaporator with liquid refrigerant at the evaporator’s low pressure, the refrigerant leaving the metering device is a low-pressure liquid (often at or near the saturated liquid state). Some vapor can form as the liquid begins to absorb heat in the evaporator, but immediately after the metering device the state is best described as low-pressure liquid. This is why options describing high pressure or vapor at the outlet aren’t correct.