Rank these leak test gases from most to least preferred, following EPA's test outline.

Leak detection · EPA 608 Type II. The correct answer, and the reasoning behind it.

Signs of leaks in high-pressure systems and leak testing before charging.

The question

Rank these leak test gases from most to least preferred, following EPA's test outline.

• APure refrigerant, nitrogen with trace R-22, nitrogen alone
• BNitrogen with trace R-22, nitrogen alone, pure refrigerant
• CNitrogen alone, nitrogen with trace R-22, pure refrigerantCorrect answer
• DNitrogen alone, pure refrigerant, nitrogen with trace R-22

Why “Nitrogen alone, nitrogen with trace R-22, pure refrigerant” is correct

EPA's order is nitrogen alone first, then nitrogen with a trace quantity of R-22, then pure refrigerant last. Each step down releases more refrigerant when the test gas is let out.

Source: EPA: Test Topics

Why the other answers are wrong

• Pure refrigerant, nitrogen with trace R-22, nitrogen alone — This is the order reversed; pure refrigerant is the least preferred.
• Nitrogen with trace R-22, nitrogen alone, pure refrigerant — Nitrogen alone ranks above nitrogen with a trace gas.
• Nitrogen alone, pure refrigerant, nitrogen with trace R-22 — Pure refrigerant ranks below nitrogen with a trace of R-22.

Practice more of this

More EPA 608 Type II practice questions, or see every EPA 608 practice test.