Type II — High-PressureCâu 127 / 240
After replacing a compressor on an R-410A system, a technician needs to remove moisture and noncondensables before charging. Which procedure is the correct way to dehydrate the system?
a.Purge the system with R-410A vapor and vent it
b.Pressurize with oxygen and hold overnight
c.Pull a deep vacuum with a vacuum pump and verify it with a micron gauge, using triple evacuation if needed
d.Blow shop air through the lines until dry
Giải thích
Proper dehydration means pulling a deep vacuum with a vacuum pump and confirming the level with a micron gauge; triple evacuation (evacuate, break vacuum with dry nitrogen, repeat) is used to remove stubborn moisture. Purging with refrigerant is illegal venting, and oxygen must never be used because it can cause an explosion with oil. Shop air introduces moisture and noncondensables.
Luyện miễn phí toàn bộ 240 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- A technician recovers R-22 with an older recovery unit manufactured before November 15, 1993 from a system holding 250 pounds. What is the required evacuation level?
- A technician must recover a large liquid charge from a supermarket rack quickly. Which recovery method moves the most refrigerant in the least time for large systems?
- A technician wants to speed up vapor recovery from an R-410A condensing unit. Which practice will increase recovery speed?
- During evacuation of a Type II system, a technician wants to confirm the system has reached a deep, dry vacuum. Which instrument gives the precise reading needed?
- A technician performs triple evacuation on a Type II system. What gas is used to break the vacuum between evacuations?
- A technician is charging an R-410A system that uses a near-azeotropic blend. To keep the blend's composition correct, how should refrigerant be removed from the cylinder during charging?
Cập nhật gần nhất: · quy trình kiểm tra
Đội Ngũ Biên Tập PrepPass · Đối chiếu với EPA Section 608 Technician Certification Exam · Quy trình kiểm tra