Type II — High-PressureQuestion 135 of 240
A technician pressure-tests a repaired R-410A system for leaks before evacuating. Which gas is appropriate for pressurizing the system for a leak test?
a.Regulated dry nitrogen (optionally with a trace of refrigerant)
b.Pure oxygen
c.Acetylene
d.Unregulated shop compressed air
Explanation
Dry nitrogen, delivered through a pressure regulator, is the correct gas for pressure-testing because it is inert and moisture-free; a small trace of refrigerant may be added so an electronic detector can find the leak. Oxygen and acetylene are dangerous and can cause explosions or fires with oil. Nitrogen must always be regulated to a safe test pressure to avoid overpressurizing the system.
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