Warehouse roof top spring-loaded pressure relief valve spring pressure relief valve positions when the pressure value is within a preset range, the coil spring bonnet remains closed. Three external spring bar so that the external annular bonnet to maintain tight closure until the pressure generated within the silo is less than the spring force. When the pressure is too high or too low in the warehouse, the pressure relief valve when the pressure exceeds a preset range, the valve cover on the last push to relieve pressure. Smaller valve cover covering the outside of the valve cover from the bottom center of the circular opening. Smaller valve cover by a single spring rod fixed to the outside and covered with pressurized air through a standard valve inside the silo. When the pump pressure, the pressure relief valve spring compression and valve cover decreased. Air from the outside into the silo, then ensure the rapid pressure balance valve cover and push the center of the closed position. The entire work process without manual operation. Widely used in the top of the storage tank material, storage hopper. Warehouse roof spring pressure relief valve is a safety valve, its opening and closing pieces by the external force is normally closed state, when the media pressure equipment or pipeline increases, automatically turn exceeds a predetermined value, through the system foreign media to prevent the discharge piping or equipment medium pressure exceeds a predetermined value. Safety valves are automatic valves, mainly for boilers, pressure vessels and piping, control pressure does not exceed the value of personal safety and equipment operation plays an important protective role. The valve is mounted on the liquid return pipe LPG station can pump when the pump before the pressure exceeds a predetermined value, the valve automatically opens and plays the role of security reflux, ensure the safe operation of equipment and piping. Warehouse roof spring pressure relief valve spring compressor and valve cover decreased. Air from the outside into the silo, then ensure the rapid pressure balance valve cover and push the center of the closed position. Pressure relief valve play a security role in the system. When the system pressure exceeds a predetermined value, the safety valve opens, the system part of the gas / fluid is discharged into the atmosphere / outside the pipeline, so that the system pressure does not exceed the allowable value, in order to ensure that the system pressure is too high and not because of the accident. Control valve, also known as relief, or relief valve, but there are some differences between it and the pressure relief valve. Several typical structure is illustrated as a safety valve. Figure A is a piston valve, the valve is a flat. Air pressure acting on the piston A, when the pressure exceeds a safe value determined by the spring force, piston A is top open, a portion of the compressed air that is discharged into the atmosphere from the valve port; when the air pressure falls below the safety value, the drive spring piston down, closes the valve port. This valve sealing surface is clean.