Which port on a pilot-operated relief valve is used to change the relief setting from a remote location?

• A. Spool
• B. Vent port
• C. Spring
• D. Poppet

Answer: (B)

Pilot-operated relief valves control the main opening pressure with a small pilot stage. The setting is determined by the pressure that acts on the pilot chamber, which in turn depends on the pilot circuit and any bleed or signal lines connected to it. The vent port is the access point to the pilot circuit, so a remote adjustment line can be connected to or vented from this port. By venting or bleeding the pilot side through the vent port (or using it to apply a remote signal), you change the pressure on the pilot valve, which shifts the pressure at which the main valve opens. This allows the relief setting to be changed from a remote location without dismantling the valve. The other elements listed—spool, spring, and poppet—are internal components and the valve’s adjustment is not performed through them.