Which gas is safe to use, along with a trace of refrigerant, to raise pressure in a low-pressure appliance for leak detection?
a.Oxygen
b.Dry nitrogen
c.Compressed shop air
d.Acetylene
Explanation
Dry nitrogen is the correct pressurizing gas, sometimes with a small amount of refrigerant so an electronic detector can sense the leak. Oxygen or compressed air can combine with refrigerant oil and explode, and acetylene is a fuel gas. Even with nitrogen, never exceed 10 psig in a low-pressure appliance.
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