Factors to be considered in selection of safety valve:

(1) The selection of safety valve structure mainly depends on the process conditions of the equipment and the characteristics of the working medium. In general, most boilers and pressure vessels use spring-loaded safety valves. For toxic, inflammable and explosive media, closed safety valve shall be selected. The boiler and high pressure vessel as well as the medium and low pressure vessels with large safety discharge capacity and small wall thickness are better to choose full open safety valve.

(2) The maximum allowable working pressure of boiler and pressure vessel should be considered in the working pressure range of safety valve.

(3) The discharge capacity of the safety valve must be greater than the safety discharge capacity of the equipment, so as to ensure that when the boiler or pressure vessel is overpressured, the opening of the safety valve can discharge part of the medium in time, so as to avoid the continuous increase of the pressure in the device. (4) For the safety valve for boiler, its total displacement must be greater than the maximum continuous evaporation capacity of boiler, and after all safety valves on drum and superheater are opened, the steam pressure in drum shall not exceed 1.1 times of the design pressure.