Abstract: A pressure relief system includes a relief valve for selectively discharging process media from a pressure vessel, a pilot valve for controlling the relief valve, and an isolation system for isolating the pilot valve from the process media. The pilot valve has an inlet port, a control port in communication with a dome chamber of the relief valve, and a discharge port. The isolation system includes an accumulator such as a piston-type or bladder-type accumulator, a source of pressurized control fluid, a pressure regulator, and a check valve. The accumulator has an interior chamber with an inlet in communication with an inlet of the relief valve and an outlet in communication with the inlet port of the pilot valve. An isolator such as a piston or bladder divides the interior chamber into a first portion and a second portion and prevents flow therebetween to isolate process media (located in the first portion) from control fluid (located in the second portion).