Given the fact that every valve needs to be operated (e.g. actuated or cycled), there are various options that play a pivotal role in operating valves such as levers, actuators, hand wheels, and gears. It can be said that one of the most heavily relied components in the manufacturing and industrial sectors is the valve actuator.
Read More: Ball Valves
What is a Valve Actuator?
It is a device that can either be electro-mechanical or mechanical and it provides control and sometimes limited positioning or movement. In other words, it is a mechanism that is used for the purposes of opening and closing of a valve. A source of power is utilized by a valve actuator to operate a valve. It can be operated manually, electrically, or by fluids.
For a valve actuator, there are two basic movements: rotary and linear. In the case of rotary actuators, energy is converted to provide rotary motion. It is used for various valves such as butterfly or ball. When it comes to linear actuators, they are manually operated with the help of a hand wheel or rotating knob because they are unpowered. There are liner chain actuators that use rigid chains to provide pull and push motions.
Each actuator type has different power configurations for various versions and that is why each type comes in different sizes and styles. Below-mentioned is some of most commonly used actuator types.
Types of Actuator
Manual Actuators: Like the name suggests, these actuators are manually operated and there is the use of wheels, levers, and gears for the purpose of moving the valve stem. They are quite commonly used due to two main reasons: (1) they are easy to operate because they are self-contained and (2) they are quite inexpensive as compared to other types of actuators.
However, one cannot neglect the fact that there are some large valves that just cannot be operated manually. That is why large valves are mostly located in remote environments.
Hydraulic Actuators: In these actuators, fluid pressure is converted into motion. A linear force/thrust is created on the global valve or gate by putting fluid pressure on a piston. These actuators are commonly used on quarter-turn or linear valves. To operate a quarter-turn valve, the rotatory motion is provided by the torque that is produced by a quarter-turn actuator. Most types of hydraulic actuators come with a fail-safe feature that ensures a valve can be successfully opened or closed under any emergency. For a hydraulic actuator, a self-contained hydraulic pressure pump can be used to supply hydraulic pressure.
Pneumatic Actuators: The main power source that is used to operate a pneumatic actuator is air or other gas (in some cases). These types of actuators are used on quarter-turn or linear valves and linear force is created on a valve system by applying pressure on a bellow diaphragm or a piston. All in all, operating energy is generated by a pneumatic actuator by utilizing compressed air. There is a wide opinion that these actuators are preferable due to their quick responding ability but if there is high pressure, these actuators are not recommended because gas is compressible.
Electric Actuators: In these actuators, a valve is operated by providing torque with the help of an electric motor. They are non-toxic, quiet actuators and energy-efficient as well. However, there is one drawback that there has to be the continuous availability of electricity for these actuators. Batteries can do the job but it is recommended to not use them for remote installations.
Spring Actuators: They are not quite commonly used because they can be operated just once (preferable for dealing with emergency circumstances). To open the valve, there is the use of a spring that is released once power is lost or any anomaly is detected. The one-use purpose of these actuators makes them best for emergencies because there is no use of powerful electric supply. They can operate automatically or from limited battery power as well.
Applications of Actuator Valves
Rotation or linear translation is produced for cylinders, incorporate motors or other motion devices by using powered actuators. Actuator valves are used in many linear motion applications as well because of the non-availability of air power or extra force that is needed for compact designs.
Linear actuators are used in production machinery, medical equipment, packaging machinery, transportation industry etc. All in all, actuators are mostly used for installation where it is either dangerous or not possible for humans to operate. Needless to say, they are considered extremely useful devices due to their diverse range of applications in various fields.