I. Overview

GRAND-GP series pneumatic actuator includes diaphragm type with straight travel and cylinder type with angular travel. Using spring balance, the air source would be added to the actuator diaphragm or the pressure on piston and pneumatic output signal, until the signal changes to determine the valve core position. The zero position setting of the actuator is determined by the compression of the actuator spring, and the travel range is determined by the spring stiffness or piston thrust of the actuator.
GP1 type actuator is action-oriented and GP2 type actuator is reaction-oriented. The design of these actuators can make the control valve switch or control reliably. 

II. Features

　1. The universality of application: To provide the actuators of two series and multiple specifications and the spring stiffness/travel limiters of multiple specifications which are applicable to almost all applications of control valves.
　2. There is an excellent linear relationship between loading pressure and travel: The diaphragm moves in the deeper diaphragm shell so that the diaphragm area has the smallest change in the whole travel range.
　3. High dynamic stability and frequency response: Small air chamber and short response time.
　4. Withstanding maximum thrust: The molded diaphragm can produce the maximum thrust at a given diaphragm size.
　5. Long service life: The cast iron and cast steel structure of the solid thick wall is highly stable to prevent the deformation resulted from over pressure, and the surface spray is corrosion resisting.
　6. Applicable to low-temperature conditions: To improve the performance of the GP1 and GP2 type pneumatic diaphragm actuators of all specifications, assure normal work at -50℃. Positioners are recommended to assure the response performance in the applications below -40℃.
　7. Rigid connection: The push rod adapter component of the block can move reliably and facilitate installation, effectively avoiding the idle motion and inaccurate valve positioning.

 III. Choice of Forms (Action and Reaction)

GP1 type actuator is an action diaphragm actuator. It will add the air source pressure to the upper diaphragm shell so that the pushrod of the actuator can move downward. When the pressure is reduced, the opposite spring force will move the actuator push rod upward. When the air source is cut off, the spring will force the actuator pushrod to the top position, providing air loss opening way to the valve closed downward.
GP2 actuator is a kind of reaction diaphragm actuators. It will add the air pressure to the lower diaphragm shell so that the actuator push rod can move upward. When the pressure decreases, the spring will force the actuator pushrod to move downward. When the air source is cut off, the spring will force the push rod down to the lowest position. Providing air loss closing way to the valve closed downward.