1, valve type selection:

     (1) determine the nominal pressure, not to cover with PMAX PN, but by the temperature, pressure, material from the table to find the three conditions of the corresponding PN and PN to meet the value of the selected valve.

     (2) to determine the valve type, the leakage to meet the process requirements.

     (3) to determine the valve type, the working pressure should be less than the valve to allow pressure, such as not, shall be elected from a special point of view or its valve.

     (4) medium temperature in the valve's operating temperature range, ambient temperature to meet the requirements.

     (5) According to the media considered not clean the valve attempts to prevent the problem.

     (6) According to the media to consider the chemical properties of corrosion resistant valves.

     (7) According to media pressure and with a hard object, consider the valve problems of erosion and abrasion.

     (8) consider the overall economic effect of performance and price ratio. Need to consider three questions:

     A, structure is simple (as simple as higher reliability), easy maintenance, a source of spare parts;

     B, life;

     C, price.

     (9) preferred order.

     Butterfly - Single-seat valve - valve seat - sleeve valve - angle valve - three way valve - Ball Valve - Eccentric rotary valve - diaphragm valve.

     2, the choice of implementing agencies:

     (1) The simplest is the pneumatic membrane, followed by the piston, and finally electric.

     (2) The main advantage of electric actuators is the driving source (power) to facilitate, but the price is high, reliability, water proof as pneumatic actuators, pneumatic it should be preferred.

     (3) old heavy electric actuator, we have electronic high-precision small to provide reliable electric actuator (price correspondingly high.)

     (4) old ZMA, ZMB film actuator can be eliminated by the implementing agency on behalf of many of the spring light (performance improvement, weight, height decreased by about 30%).

     (5) piston actuator specification more variety, the old, big, stupid advice is no longer used, and use the new structure of light.