What are the choice of pneumatic actuators correct method

We are in need of pneumatic actuators, will choose to suit to the pneumatic actuator, high cost performance of the pneumatic actuator, so must first understand the types of actuators, pneumatic actuators and electric actuators can be divided into actuators, actuators which are frequently used both, we will choose the choose and buy when the pneumatic actuators. Then we will choose according to the size of the air supply to the actuators, turn the valve required torque, size don't understand, too big valve life is not long. Generally the torque to set aside the % margin with respect to OK. Secondly we carries on the inspection for the installation of the platform, each environment choose actuators, for actuator has a standard, we need to find the corresponding standard according to the valve is not wrong. Based on electric, electric switch type. Passive contact type and external regulation. We just according to the size of the flow valve to control the can to option.