Why should pressure relief valves not be installed in series?

Installing pressure relief valves in series can lead to insufficient pressure release, particularly because the downstream valve may not function effectively if the upstream valve is partially or fully closed. In a series arrangement, the first valve may not relieve pressure adequately if it is unable to respond to the pressure increase, which means the second valve might never reach the point where it needs to open. This can create serious safety risks, as the combined setup could fail to relieve pressure adequately, leading to overpressure situations or potential catastrophic failures in the system.

In contrast, installing relief valves in parallel allows each valve to independently handle pressure release, ensuring that if one valve fails or is unable to operate due to system dynamics, the others can still function properly. This redundancy is critical for maintaining safety and system integrity.

Other considerations, such as spatial constraints, flow rates, and ease of repairs, can influence the configuration of pressure relief systems, but the primary focus must always be on ensuring that pressure relief is effective and reliable.