Open Bonnet Safety Valve Factory: Open Bonnet Pressure Relief Valves, ASTM A216 WCB, 12 X 14 Inch, Class 150 LB, Open Bonnet, Full Lift, Lever, Flanged. When the static pressure at the inlet of the safety valve reaches the set pressure, the position of the disc increases proportionally with the increase of the inlet pressure (not less than 1/4 of the bore diameter). The lift safety valve is suitable for equipment or pipelines of incompressible fluids with working temperature ≤300°C as an overpressure protection device. Bonnet: The bonnet of the safety valve is open, allowing the spring chamber to communicate with the atmosphere, which is beneficial to reduce the temperature of the spring, and is mainly suitable for containers of high temperature gas in which the medium is steam and does not pollute the atmosphere. Lever: The safety valve can be opened manually by the lever when the media pressure over 75% of the setting pressure (On the premise of ensuring safety).