Type III — Low-PressureCâu 199 / 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.Vent refrigerant to lower the pressure
c.Add nitrogen and refrigerant to raise pressure above atmospheric, staying under 10 psig
d.Pressurize with oxygen to 15 psig
Giải thích
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.
Luyện miễn phí toàn bộ 240 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- 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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