In a dual pressure relief valve system, what valve should be installed to work on one pressure relief valve while allowing the other to operate?

In a dual pressure relief valve system, a three-way valve is ideal for selecting which pressure relief valve to operate while allowing the other to remain functional. The purpose of a three-way valve is to connect and allow flow between two paths, where it can direct fluid from one source to either of two outputs.

In this case, the three-way valve can be configured to channel fluid from the system to either of the relief valves, enabling one to operate while isolating the other. This feature is particularly useful for maintenance or troubleshooting, as it allows for the isolation of one valve without interrupting the operation of the second valve.

A two-way valve would only allow for a simple open/close function, lacking the ability to facilitate flow to one valve while isolating the other. A four-way valve introduces unnecessary complexity and is typically used for applications requiring multiple flow paths, which is not the case here. A check valve, on the other hand, is designed to prevent backflow and would not function to direct flow between two relief valves.

Therefore, the three-way valve serves the specific requirement of managing operations between two pressure relief valves effectively.