Type III — Low-PressureQuestion 199 of 240
Which practice is correct when leak testing a low-pressure chiller that is under a vacuum?
a.Draw a deeper vacuum to reveal leaks
b.Raise it with nitrogen, under 10 psig
c.Pressurize with oxygen to 15 psig
d.Vent refrigerant to lower the pressure
Explanation
To make a leak show outward, pressure must be raised above atmospheric, using nitrogen with a trace of refrigerant while staying at or below 10 psig. A deeper vacuum keeps leaks pulling air inward where a detector cannot sense them, venting is illegal, and oxygen is dangerous.
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Related questions on this topic
- Which of the following is NOT a low-pressure appliance refrigerant?
- Excessive water in a low-pressure chiller can freeze and rupture tubes because low-pressure refrigerants:
- When handling a large recovery cylinder of R-11 removed from a chiller, the technician must remember to:
- A high-efficiency purge unit on a chiller is often equipped with a purge-rate log because a rising rate:
- The deep 25 mm Hg absolute recovery requirement exists for low-pressure appliances because:
- The main safety concern that sets the 10 psig pressurization limit on low-pressure appliances is:
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