In systems using positive displacement compressors, the stop valves must be installed at which locations if the refrigerant charge exceeds 6.6 pounds?

In systems using positive displacement compressors, the stop valves must be installed at which locations if the refrigerant charge exceeds 6.6 pounds?

• A. At the inlet of each compressor and at the discharge outlet of each compressor and liquid receiver
• B. Only at the discharge outlet of the compressor
• C. Only at the refrigerant pump-out location
• D. Not required if there is a receiver

Answer: (A)

In systems with positive displacement compressors, you need the ability to completely isolate the compressor and the receiving portion of the system when the refrigerant charge is large. When the charge exceeds 6.6 pounds, locating stop valves at the suction inlet of each compressor, at the discharge outlet of each compressor, and at the liquid receiver provides that isolation path. Having a valve on the suction side lets you stop refrigerant from entering the compressor during maintenance, preventing damage from attempting to run with the line blocked. A valve on the discharge side blocks the high-pressure path, stopping any backflow into other components and enabling safe pump-down or service without contaminating or losing more refrigerant. A valve at the liquid receiver allows isolating the receiver from the rest of the system, so you can service or pump down the receiver without venting the entire charge. This arrangement reduces risk of liquid slugging, backflow, and unintended refrigerant loss, and it makes maintenance safer and easier.

In systems with positive displacement compressors, you need the ability to completely isolate the compressor and the receiving portion of the system when the refrigerant charge is large. When the charge exceeds 6.6 pounds, locating stop valves at the suction inlet of each compressor, at the discharge outlet of each compressor, and at the liquid receiver provides that isolation path.

Having a valve on the suction side lets you stop refrigerant from entering the compressor during maintenance, preventing damage from attempting to run with the line blocked. A valve on the discharge side blocks the high-pressure path, stopping any backflow into other components and enabling safe pump-down or service without contaminating or losing more refrigerant. A valve at the liquid receiver allows isolating the receiver from the rest of the system, so you can service or pump down the receiver without venting the entire charge. This arrangement reduces risk of liquid slugging, backflow, and unintended refrigerant loss, and it makes maintenance safer and easier.