What is the required cross-sectional area for a discharge pipe used on a safety valve?

The required cross-sectional area for a discharge pipe used on a safety valve should be the full area of the valve outlet. This is necessary to ensure that the maximum flow rate through the valve is not restricted, allowing the safety valve to function properly and release pressure efficiently during critical situations.

Using an area less than the full outlet area could create a bottleneck, restricting the flow of discharge. This could lead to excessive pressure buildup in the system if the safety valve needs to open and alleviate pressure but is obstructed by the discharge pipe’s cross-sectional area. Therefore, matching the discharge pipe's cross-sectional area to the full area of the valve outlet is essential for the proper operation and safety of the system. This requirement is emphasized in various plumbing codes and standards to ensure safety equipment performs effectively under emergency conditions.