In the scotch yoke pneumatic actuator, we often hear the film pneumatic actuator, both belong to the pneumatic actuator, but there are great differences between the two. Let's compare the difference between the film pneumatic actuator and the scotch yoke pneumatic actuator.
Pneumatic membrane valve is simple in structure, convenient in maintenance and widely used, but its output force is small, which is used to regulate flow. The scotch yoke pneumatic actuator output force is larger for large caliber, high differential pressure valves and butterfly valves, generally used for cut-off and switching control.

Pneumatic film control valve is called control valve for short. It consists of actuator and control mechanism. The development of pneumatic film valve has been 80 years since the beginning of the 20th century. Ten kinds of valve products, self-operated valve and positioner, have been produced successively.

The regulating valve consists of an electric actuator or a pneumatic actuator and a regulating valve. Regulating valves are usually divided into two types: through single-seat regulating valve and through double-seat regulating valve. The latter has the characteristics of large flow capacity, small imbalance and stable operation, so it is usually especially suitable for large flow, high pressure drop and less leakage. Regulating valve is the most widely used type of final control element. Other final control elements include metering pump, regulating baffle and shutter baffle (a variant of butterfly valve), fan blade with variable slope, current regulating device and motor positioning device different from valve. Although regulator valves are widely used, other units in the regulator system probably do not have as little maintenance work as it does.
In many systems, the operating conditions such as temperature, pressure, corrosion and pollution of the control valve are more severe than those of other parts.
It is more serious, however, when it controls the flow of process fluid, it must operate satisfactorily and maintain at a minimum.
The scotch yoke pneumatic actuator is the actuating unit in the pneumatic unit combination instrument. It receives from the regulator.
The signal of the meter controls the cut-off and switching-on or switching-off of the flow passage in the process pipeline. The product has the advantages of large operating force, novel valve body design, small flow resistance, large rated flow coefficient, large allowable pressure difference and excellent sealing performance. Thus widespread
It is applied to automatic control and remote control system of production process in petroleum, chemical, metallurgical, electric power, textile and other industrial sectors.
There are two kinds of fork-type actuators: single-acting (spring reset) and double-acting (double intake). Using single-acting actuator, the whole machine can be divided into air-closed (horizontal pipeline connected) and air-opened (horizontal pipeline disconnected). The scotch yoke pneumatic actuator has two sealing forms, hard seal and soft seal, which are suitable for different temperatures and pressures. Two-position three-way cut-off valve adopts four-way valve body with three channel ports, which is especially suitable for switching between two flow paths. When the signal pressure is zero, the valve core is in the initial state because of the pre-tightening force of the spring (single action only). When the actuator receives the signal pressure (0.4-0.6 MPa), the compression spring drives the push rod, the valve body and the valve core to move to the limit position to make the valve fully open or closed. To achieve the medium in the pipeline to connect, cut off or switch between pipelines control. The two-position three-way electric sample valve is used to make the control of the fork-type pneumatic actuator more convenient and simple.
Do you have any idea about the comparison between membrane type and scotch yoke pneumatic actuator? If you have the demand of fork pneumatic actuator, you are welcome to contact us or login to Ruito official website for consultation.