Core Concepts and Principles Flashcards

What is the main purpose of evacuating (dehydrating) a refrigeration system?

Answer: To remove air, moisture, and non-condensables

Evacuation removes air and moisture that would cause high pressures, acid, and sludge.

Which instrument is used to accurately measure the deep vacuum during dehydration?

Answer: Micron gauge

A micron (thermistor) vacuum gauge measures the very low pressures needed to confirm dehydration.

Which practice speeds up system dehydration?

Answer: Raising the system temperature

Warmer system temperatures help moisture vaporize so the vacuum pump can remove it faster.

When moisture mixes with CFC or HCFC refrigerant in a system, what harmful substances can form?

Answer: Hydrochloric and hydrofluoric acids

Moisture reacts with chlorine- and fluorine-based refrigerants to form corrosive acids.

What is the primary danger of a large refrigerant leak in an enclosed space?

Answer: Oxygen displacement causing asphyxiation

Refrigerant vapor is heavier than air and can displace oxygen, causing suffocation.

Exposing refrigerants like R-22 to an open flame or very hot surface can produce:

Answer: Phosgene and other toxic gases

Decomposing halogenated refrigerants can form toxic phosgene, hydrochloric acid, and hydrofluoric acid.

Why is a halide torch leak detector ineffective for finding leaks of HFC refrigerants such as R-134a?

Answer: HFCs contain no chlorine to react with the copper element

The halide torch flame changes color only in the presence of chlorine, which HFCs lack.