Selection basis: First, according to the selection of solenoid valve parameters: Path Specifications (ie, DN), interface mode 1, in accordance with the size of the pipeline diameter or flow requirements to determine the path (DN) size. 2, interface, general> DN50 flange interface to choose, ≤ DN50 can be freely selected according to user needs. Second, select the solenoid valve according to the fluid parameters: Material, temperature group 1, corrosive fluid: Corrosion-resistant solenoid valves and stainless steel should be used; Super clean fluid consumption: should choose food-grade stainless steel solenoid valve. 2, high temperature fluid: To choose the use of high temperature resistant electrical materials and sealing materials manufactured solenoid valve, but also to choose the type of piston structure. 3, the fluid state: as large as a gas, liquid or mixed state, especially when the diameter greater than DN25 must be distinguished when ordering. 4, fluid viscosity: usually below 50cSt can be arbitrarily selected, if more than this value, then the choice of high viscosity solenoid valve. Third, select the solenoid valve according to the pressure parameters: Principle and structure Variety 1, nominal pressure: This parameter and the meaning of other common valves is the same, is based on the pipe nominal pressure to be set. 2, working pressure: If the work pressure is low, you must choose the principle of direct acting or step-by-step direct acting; minimum working pressure differential above 0.04Mpa direct acting, step by step direct acting, pilot can be used. Fourth, the electrical options: Voltage specifications should try to be preferred AC220V, DC24 more convenient. Fifth, according to the duration of the continuous work to choose: normally closed, normally open, or continuous power 1, when the solenoid valve needs a long time to open, and the duration of the excess off time should be used normally open type. 2, if the opening time is short or open and close time is not long, then choose the normally closed type. 3, but some for security conditions, such as furnaces, kiln flame monitoring, you can not choose the normally open, should be elected long-term power type. Six, according to environmental requirements to choose auxiliary functions: Explosion-proof, non-return, manual, water fog, water leaching, diving 1, explosive environment: the appropriate explosion-proof solenoid valve must be selected (my company: d II BT4, d II CT5, Ex m I / II T4).