All systems containing more than how many pounds of refrigerant in systems using positive displacement compressor shall have stop valves installed?

The correct answer relates to the requirement for systems utilizing positive displacement compressors, which have specific regulations for refrigerant management. Specifically, systems that contain more than 6.6 pounds of refrigerant must be equipped with stop valves. These valves are crucial because they help prevent refrigerant leakage during maintenance, servicing, and system repairs, thereby adhering to safety and environmental standards.

Having stop valves allows technicians to isolate the refrigerant from the system, ensuring that when servicing is conducted, the refrigerant does not escape into the atmosphere, which can be harmful both to the environment and human health. This requirement is outlined in various safety and code regulations designed to promote safe handling practices in HVAC systems.

Additionally, the significance of the specified weight, 6.6 pounds, indicates a threshold beyond which the potential risk of refrigerant release increases, warranting additional safety measures. This is aligned with industry standards aimed at protecting both workers and the environment from unnecessary refrigerant exposure.