Refrigerant piping installations with over how many pounds should not have stop valves at the inlet of each receiver?

In refrigerant piping installations, the requirement for stop valves at the inlet of each receiver is determined by the total refrigerant charge in the system. When the refrigerant charge exceeds a certain weight, typically around 6.6 pounds, stop valves are prohibited at the inlet of each receiver. This regulation is in place to ensure safety and to prevent issues such as system pressure imbalances and potential refrigerant leaks, which could occur if a stop valve were to be closed while there is a significant amount of refrigerant in the system.

Having stop valves in systems with a larger refrigerant charge can complicate maintenance and emergency procedures, as isolating sections of the system may lead to excessive pressures within the components. Therefore, adhering to the guidelines regarding the installation of stop valves based on refrigerant weight is crucial for safe and efficient operation of HVAC systems. This safety measure is reflected specifically at the threshold of 6.6 pounds, which aligns with industry standards for refrigerant management in larger systems.