Discussion on valve actuators

As far as I know, hydraulic systems involve setting up a single oil station from which the oil is distributed to various hydraulic actuators; they are mainly used in areas of a factory where there are many valves. Pneumatic-hydraulic actuation is often used in remote areas where it is difficult to lay cables; the medium in the pipes is compressed gas (such as in the West-East Gas Pipeline), and this compressed gas is used as power to drive oil, which in turn operates the actuator. Electro-hydraulic actuation is rare; one actuator corresponds to one motor that increases the pressure of the drive oil to operate the valve. It’s just one person’s opinion; it shouldn’t be taken too seriously!

Pneumatic and hydraulic devices are mostly composed of pressure cylinders driven by compressed gas or hydraulic fluid; a few are composed of reduction gears driven by pneumatic or hydraulic motors. The former is widely used in partial rotary and linear reciprocating drives; the latter can be used as multi-turn rotary drives, and some of them can be used interchangeably with electric devices. They all feature a compact design and rapid opening/closing, making them suitable for use indoors or in environments with corrosion, fire, or explosion hazards; their drawback is that the piping system is complex, and they are not suitable for remote control. The pressure of pneumatic devices is generally (4–6)×105 Pascals, with relatively low output. The hydraulic device uses high pressure, resulting in greater output. Electric actuator: A device that uses a motor to drive a reduction mechanism in order to operate the valve. Some are driven by electromagnetic force to operate the valve (see solenoid valve). The electric actuators for valves come in two types: multi-turn and partial-turn. It is characterized by convenient power supply, easy adjustment, and high output, making it suitable for remote control and automatic control applications, and it is widely used. However, during design and manufacturing, it is necessary to consider the impact of outdoor conditions as well as flammable and explosive environments on electric devices, and its structure is relatively complex. Pneumatic-hydraulic actuators and electro-hydraulic actuators are hydraulic mechanisms that use compressed gas or electricity as a power source. The common type is the partial rotation type, which is characterized by fast operation and high torque, enabling it to drive large-diameter valves. This type of device is commonly used as shut-off valves or emergency automatic shut-off valves in long-distance oil and gas transmission pipelines.

I have used hydraulic systems; they are used in situations with high pressure differences and offer fast response times. They consist of a motor, an oil pump, an oil tank, as well as hydraulic rods. Pneumatic systems are more common, and many chemical plants use them. There are mainly two types of such systems: those with gear strips and those with shift forks