Type II — High-PressureCâu 130 / 240
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?
a.As vapor only, from the top of an upright cylinder
b.By venting a little first to purge the cylinder
c.As vapor into the high side while running
d.As liquid (cylinder inverted or using the liquid port), often metered to avoid slugging the compressor
Giải thích
Zeotropic and near-azeotropic blends like R-410A must be charged as liquid so all components leave the cylinder in the correct proportion; removing vapor would fractionate the blend. Liquid is typically drawn from an inverted cylinder or a liquid valve and metered or flashed to vapor before it reaches the compressor to prevent slugging. Charging vapor from the top can change the blend's composition.
Luyện miễn phí toàn bộ 240 câu hỏi — không cần đăng ký.
Câu hỏi liên quan cùng chủ đề
- 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?
- 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 checks the charge on an R-22 system that uses a fixed orifice (piston) metering device. Which measurement is the primary method to verify the charge?
- 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?
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