All systems containing how many pounds or more of a refrigerant must have stop valves?

The correct answer highlights the importance of safety and regulation in handling refrigerants within mechanical systems. The North Carolina Mechanical Code specifies that systems containing 100 pounds or more of refrigerant must have stop valves. These valves are critical for isolating sections of refrigerant piping, allowing for maintenance and servicing without the risk of refrigerant leaks that could pose safety hazards.

Having stop valves in systems with this quantity of refrigerant ensures that technicians can effectively control the flow of refrigerant during service procedures, which is essential for protecting both the workers and the environment. Moreover, it is a requirement aimed at preventing accidental discharges in case of maintenance or emergency situations.

Therefore, understanding the threshold of 100 pounds is vital for compliance with safety regulations and ensuring that refrigeration systems can operate safely and efficiently.