What kind of pipe or system must relief valves discharge into?

Relief valves are designed to prevent excessive pressure within a system by discharging excess pressure or fluid. It’s critical that the discharge from a relief valve goes into an open receptacle. This open configuration allows any fluids or gases to escape freely, ensuring that the system can return to a safe operating condition without the risk of creating a closed or pressurized environment which could lead to additional hazards.

When the relief valve discharges into an open receptacle, there is no pressure buildup and the fluid or gas can dissipate safely into the atmosphere or be directed to a drainage system. This is crucial in maintaining the integrity of the plumbing or mechanical system, as closed systems can cause dangerous over-pressurization, leading to potential explosions or leaks.

In contrast, discharging into a closed receptacle, a sealed tank, or the groundwater could result in unsafe situations, such as contamination, pressure buildup, or failure of the tank or system due to insufficient venting. Thus, the requirement is to ensure that relief valve discharges are managed in a way that prioritizes safety and compliance with plumbing codes.