What are the types of valve actuators? Examples include: manual, gear-driven, pneumatic, electric, etc.

A valve actuator is a device used to operate and connect to a valve. Based on the power source, it can be classified as manual actuators, gear-driven actuators, pneumatic actuators, hydraulic actuators, electric actuators, pneumatic-hydraulic linkage actuators, and electro-hydraulic linkage actuators.

A actuator is a device used to operate and connect to a valve. This device can be driven by a manual, electric, pneumatic, hydraulic, or a combination of these power sources. Its movement can be controlled by the magnitude of stroke, torque, or axial thrust.

Multi-turn actuators: When the actuator transmits torque to the valve, the output shaft can rotate at least one revolution and can withstand thrust.

Partial-turn actuators: When the actuator transmits torque to the valve, the output shaft rotates less than one revolution. It is not required to withstand thrust.

A valve actuator is a device that uses external power to open and close a valve. The purpose of using an actuator is to make valve operation easier, more convenient, faster, and more reliable, or to achieve automatic control and remote control. The basic requirements for valve actuators are: torque or thrust sufficient to meet the valve's opening and closing needs; accurate and reliable control of stroke and torque; appropriate power source for site conditions; opening and closing actions conforming to control requirements; and compact design.

Valve actuators are classified into three types based on their output shaft movement: multi-turn, partial-turn, and linear reciprocating. Multi-turn actuators, also known as multi-rotation actuators, are suitable for valves where the valve stem or nut requires multiple rotations to fully open or close, such as gate valves and globe valves. The output torque range is typically 40–10000 Nm (thrust 20–1100 kN). Partial-turn actuators are suitable for valves where the valve stem can fully open or close within one rotation, such as ball valves and butterfly valves. Their output torque range is typically 125–125000 Nm. Linear reciprocating actuators are suitable for valves where the valve stem only requires linear reciprocating motion to fully open or close, such as solenoid valves.

Valve actuators can be categorized by power source into manual actuators, gear-driven actuators, pneumatic actuators, electric actuators, hydraulic actuators, pneumatic-hydraulic linkage actuators, and electro-hydraulic linkage actuators. The most primitive and simplest valve actuators are handwheels and handles. With the increasing size of valves and the automation of production processes, the need for various valve actuators is growing. Valve actuators play a crucial role in industrial automation.

Manual actuators are manually operated reduction gears used to reduce the force required to manually operate valves. They are typically of two types: multi-turn and partial-turn. Their characteristics include simple structure and easy operation. They are commonly used to drive valves with a nominal diameter of less than 300 mm.

Gear-driven actuators are mechanical transmissions that utilize the meshing of two gears to transmit power and motion. Gear drives are characterized by smooth transmission, accurate transmission ratios, reliable operation, high efficiency, long service life, and a wide range of applicable power, speed, and size.

Pneumatic and hydraulic actuators mostly consist of pressure cylinders driven by compressed gas or hydraulic pressure, while a few consist of reduction mechanisms driven by pneumatic or hydraulic motors. The former is widely used for partial rotary and linear reciprocating drives; the latter can be used for multi-turn rotary drives, and some are compatible with electric actuators. Both are characterized by their compact structure and rapid opening and closing, making them suitable for indoor environments or corrosive, flammable, and explosive environments. Their disadvantages include complex piping and unsuitability for remote control. Pneumatic actuators typically operate at pressures of (4-6) × 10⁵ Pa, with relatively low output. Hydraulic actuators use higher pressures and have greater output.

Electric actuators are devices that use an electric motor to drive a reduction gear mechanism to operate valves. Some are driven by electromagnetic force (see solenoid valves). Electric actuators for valves come in two types: multi-turn and partial-turn. Their advantages include convenient power supply, easy adjustment, and high output, making them suitable for remote and automatic control needs and widely used. However, the design and manufacturing process must consider the impact of outdoor, flammable, and explosive environments on the electric actuator, and the structure is relatively complex.

Pneumatic-hydraulic linkage devices and electro-hydraulic linkage devices consist of hydraulic mechanisms powered by compressed gas or electricity. The most common type is the partial rotary type, characterized by rapid action and high output, capable of driving large-diameter valves. This type of device is often used as a shut-off valve or emergency automatic shut-off valve in long-distance oil and gas pipelines.