Refrigerant piping systems containing how many pounds or more must have stop valves on each inlet of each liquid receiver?

The requirement for having stop valves on each inlet of each liquid receiver in refrigerant piping systems is based on safety and system management considerations. Specifically, when a system contains 100 pounds or more of refrigerant, it is essential to have stop valves installed to ensure that the refrigerant can be isolated in case of maintenance or emergencies. This facilitates safe servicing of the system and helps contain refrigerant leaks.

Having stop valves allows for control over the flow of the refrigerant, aiding not just in maintenance scenarios but also in potential leak containment, which is critical for environmental safety and compliance with regulations. Systems containing less than 100 pounds of refrigerant do not have the same stringent requirement, as the potential hazards and management complications associated with larger quantities of refrigerant are diminished.

This regulation aligns with safety standards aimed at minimizing risks associated with refrigerants, which can be harmful if released into the atmosphere. The specific threshold of 100 pounds was established based on industry practices and the understanding of refrigerant properties, ensuring that adequately sized systems maintain safe operational parameters.