Which of the following is TRUE regarding the installation of refrigerant piping with positive-displacement compressors?

When dealing with positive-displacement compressors, proper refrigerant piping installation is crucial for efficient operation and safety. The correct understanding here is that for systems utilizing positive-displacement compressors, stop valves at the inlet of each receiver are not required if the refrigerant charge exceeds a specified limit. Specifically, when the refrigerant amount is above 6.6 lbs, the system is often designed to ensure that the pressure and capacity of the refrigerant will not create issues if the stop valve is absent. This facilitates a more efficient circulation of refrigerant, as it avoids potential blockages or hindrances in the flow that may occur with unnecessarily installed stop valves.

Having stop valves is more critical in lower charge systems, where controlling and potentially isolating parts of the system becomes essential for maintenance or safety reasons. However, once the charge exceeds the mentioned threshold, systems are generally designed to operate securely without the need for these valves at each inlet, as longer runs of piping and higher pressures typically mitigate risks associated with refrigerant flow disruption.

In summary, for positive-displacement compressors, the appropriate installation of refrigerant piping considers the amount of refrigerant and the associated operational requirements, validating that stop valves are not necessary at the inlet if the system is designed to handle higher