Type II — High-PressureCâu 135 / 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.Acetylene
b.Regulated dry nitrogen (optionally with a trace of refrigerant)
c.Unregulated shop compressed air
d.Pure oxygen
Giải thích
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.
Luyện miễn phí toàn bộ 240 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- A technician is checking the charge on a system equipped with a thermostatic expansion valve (TXV). Which measurement is the preferred way to verify the charge on a TXV system?
- A technician fills a DOT recovery cylinder with recovered R-22. To prevent a dangerous hydrostatic rupture, the cylinder must not be filled beyond what fraction of its capacity?
- A technician needs to locate a small refrigerant leak on an R-22 condensing unit. Which method is a recognized leak-detection technique?
- A technician notices R-410A gauge pressures running much higher than an equivalent R-22 system at the same conditions. What does this reflect about R-410A?
- A technician plans to retrofit an old R-22 system to an HFC blend that uses polyolester (POE) oil. Which statement about the retrofit is correct?
- A technician handles a high-pressure refrigerant cylinder in a hot truck bed in summer. Which practice is safest for storing and transporting the cylinder?
Cập nhật gần nhất: · quy trình kiểm tra
Sen Lin, Người sáng lập PrepPass · Đối chiếu với EPA Section 608 Technician Certification Exam · Quy trình kiểm tra