Features Cartridge type assembly which can be withdrawn from the body without disturbing the spring setting, and hence relieving pressure, allows the seating surfaces to be cleaned without the need to reset the valve. 480 is a bronze relief valve. 485 is bronze with a renewable stainless steel seat and disc. 490 is all stainless steel. Spindle normally fitted with an ‘O’ ring to protect the spring, particularly on corrosive duties.