BRAYS valves, pneumatic actuators safe, reliable, low cost, convenient usage and maintenance, is one of the valve actuation structure big branch. At present the pneumatic actuators with the requirements of the explosion in application occasion more. The valve actuators used the air pressure is lower, generally not more than 0.82 MPa. And because structure size shoulds not be too big, so the valve actuators can be very large not total thrust. A pneumatic actuators, valves, the use of air pressure conditions work? 0.4 ~ 0.7 (MPa) environment temperature and the temperature of the medium? 5 ~ 60 (℃) piston the speed of work and leaves linear path? 10 ~ 500 (mm/s) control feedback signal? 4 ~ 20 mA 2, valve actuators classification of valve actuators according to the structure characteristics are divided into three types: film type the pneumatic actuators, cylinder or pneumatic actuators, the swinging type the pneumatic actuators. In addition to the pneumatic motor type the pneumatic actuators. Film type? 1, film cylinder? 2, the diaphragm (1) disc diaphragm (2) flat diaphragm? 3, spring? 4, piston cylinder type? 1 single cylinder cylinder (1), (2) the two cylinder? 2, the piston and piston rings (1) O form sealing ring (2) J form sealing ring (3) U shape sealing ring (4) V sealing ring? 3, piston rod? 4, manual operator? 5, pneumatic accessories (1) loop system (2) signal back to road (3) air filter (4) pressure reducing valve oil mist device (5) directional control valve control swinging type? 1, cylinder body? 2, stator? 3 and the rotor? 4, leaf three, all kinds of pneumatic actuators the structure characteristics of the film type trip short, < 40 mm, compact structure, flexible, no manual institutions cylinder type longer journeys, when necessary and buffering mechanism, the output is not enough with double cylinder structure, manual and hand pneumatic switch structure of simple structure, swinging low cost, reciprocating motion directly into a rotation movement pneumatic motor type can be directly instead of valve electric actuator are become motor pneumatic actuators, so has the torque control of electric power equipment, and other functions, but complex cylinder actuators classic and the relationship between the classics buffer trip cylinder (mm) buffer stroke length (mm) four, the pneumatic actuators main parts material and its processing precision pneumatic actuators main parts material and heat treatment requirements.