CoreDifficulty 2/5
Why does EPA's Core topic list require nitrogen rather than oxygen or compressed air for pressurised leak detection?
- AOxygen and compressed air can form a combustible mixture with refrigerant oil
- BOxygen and compressed air dissolve into the refrigerant and contaminate the charge
- COxygen and compressed air cannot reach the pressure a leak test actually requires
- DOxygen and compressed air are not permitted inside a certified recovery machine
Show answer and rationale
Correct: A. Compressing oxygen in the presence of hydrocarbon oil is an explosion risk, which is why the rule pairs the nitrogen requirement with a pressure regulator and a relief valve.
- B — Contamination is a genuine concern with air and moisture, but it is not the safety reason given.
- C — Both can reach test pressures easily; capability is not the objection to using them.
- D — The restriction concerns pressurising the appliance for a leak test, not recovery machine internals.