Safety valve is one of the important protective devices of oil and gas fired boiler. It is very necessary for boiler users to understand the correct installation of safety valve. The main points of safety valve installation of oil and gas fired boiler are as follows:

(1) Oil fired and gas-fired boilers with rated evaporation capacity greater than 0.5t/h shall be equipped with at least two safety valves; Oil fired and gas-fired boilers with rated evaporation capacity less than or equal to 0.5t/h shall be equipped with at least one safety valve. Safety valves must be installed at the outlet of separable economizer and steam superheater.

(2) The safety valve shall be vertically installed at the highest position of boiler drum and header. Between the safety valve and the drum or header, there shall be no outlet pipe or valve for taking steam.

(3) The lever type safety valve shall be equipped with a device to prevent the heavy hammer from moving automatically and a guide frame to limit the lever from derailing. The spring type safety valve shall be equipped with a lifting handle and a device to prevent the adjusting screw from being unscrewed.

(4) For boilers with rated steam pressure less than or equal to 3.82 MPa, the throat diameter of safety valve shall not be less than 25 mm; For boilers with rated steam pressure greater than 3.82 MPa, the throat diameter of safety valve shall not be less than 20 mm.

(5) The sectional area of the connecting pipe between the safety valve and the boiler shall not be less than the inlet sectional area of the safety valve. If several safety valves are installed on a short pipe directly connected with the drum, the cross-sectional area of the short pipe shall not be less than 1.25 times of the exhaust area of all safety valves（ 6) Generally, the safety valve shall be equipped with exhaust pipe, which shall be directly connected to the safe place with sufficient cross-sectional area to ensure smooth exhaust. A drain pipe connected to a safe place shall be installed at the bottom of the exhaust pipe of the safety valve, and valves are not allowed to be installed on the exhaust pipe and drain pipe.