Which practice is safest when pressure-testing a system for leaks?
Explanation
Leak testing should be done with regulated dry nitrogen because it is inert and will not react, and oxygen or acetylene must never be used since they can cause a violent reaction or explosion in the presence of oil or refrigerant. Compressed air can introduce moisture and, mixed with refrigerant under heat, form combustible conditions. Always use a pressure regulator so the system is not over-pressurized.
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