EPA 608 Type II Practice Test 3 Flashcards

What is subcooling in a high-pressure refrigeration system and how is it measured?

Answer: Temperature of liquid refrigerant below its saturation temperature at the measured pressure; measured at the liquid line

Subcooling is the number of degrees a liquid refrigerant is cooled below its saturation temperature at a given pressure. It is measured at the liquid line by comparing actual refrigerant temperature to the saturation temperature at the measured liquid line pressure. Proper subcooling (typically 10-20°F) ensures liquid refrigerant arrives at the expansion device without flashing, improving system efficiency.

When replacing a TXV (thermostatic expansion valve) on an R-410A system, why must a filter-drier also be replaced?

Answer: Opening the system introduces moisture that the existing drier may not be able to absorb

Every time a refrigerant system is opened to the atmosphere, moisture enters. The existing drier may already be saturated from previous moisture absorption and will not be able to handle additional moisture. Replacing the filter-drier whenever the system is opened ensures fresh desiccant is present to absorb new moisture, protecting the system from acid formation and ice blockage.

A Type II system has an evaporator saturation temperature of 20°F and a suction line temperature of 45°F. What is the suction line superheat?

Answer: 25°F

Superheat equals the actual suction line temperature minus the saturation temperature at the suction pressure. 45°F (actual) − 20°F (saturation) = 25°F superheat. This value falls within a typical acceptable range for many commercial refrigeration systems. Technicians use this calculation to evaluate whether the expansion device is feeding the evaporator correctly.

On a Type II split system, what does an excessively long refrigerant line set do to system performance?

Answer: It increases pressure drop and can reduce system capacity and efficiency

Long refrigerant line sets increase pressure drop in both suction and liquid lines. Suction line pressure drop causes the compressor to operate at a lower suction pressure, reducing capacity and efficiency. Excessive liquid line pressure drop can cause flash gas before the expansion device, further reducing system performance. Line set sizing must account for length and refrigerant type.

Which is the correct safety precaution when using an oxy-acetylene torch near refrigerant lines?

Answer: Ensure all refrigerant is recovered before applying heat, as heat decomposes refrigerant into toxic gases

All refrigerant must be recovered before using any heat source on refrigerant lines. When refrigerant (especially CFCs and HCFCs) is exposed to high heat, it decomposes into phosgene gas and hydrogen fluoride/chloride — highly toxic substances. Even small amounts of residual refrigerant can produce dangerous concentrations. NEVER apply heat to a system with refrigerant present.

What is the purpose of a "pump-down" cycle in a Type II split system?

Answer: To move the refrigerant charge into the outdoor condenser/receiver before service or shutdown

A pump-down cycle uses the compressor to transfer refrigerant from the low side into the condenser and receiver (liquid storage area) on the high side before service or extended shutdown. By isolating the refrigerant in the outdoor unit, the technician can work on indoor components (evaporator, TXV, etc.) with minimal refrigerant exposure. It is not a substitute for full recovery when opening the system.