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What is a valve actuator?
A valve actuator is the mechanism for opening and closing a valve. Manually operated valves need someone in attendance to adjust them using a direct or geared mechanism attached to the valve stem.
To begin with, valve actuators are a type of control valve. Though it is a simple concept, it comprises a box that has an input, output and a mechanism that operates it. However, before you make your decision, there are a few things that you must be aware of that comes with it, which include:
- Not heavy on the pocket
- Comes with an inherent failure-mode action
- Low supply-pressure requirement
- Easily adjust to varying conditions
- Easily maintained
Types of valve actuators
Now that we understand what is a valve actuator, let us talk about the different kinds of valve actuators that are present. The majority of them fall into common categories and are categorised based on power applied and the kind of movement required:
1. Pneumatic and hydraulic actuators (fluid power) – quarter-turn
They are known for their versatile nature and are used where electrical power is not easily available or in applications where reliability and simplicity are of crucial importance. They have many capabilities, to begin with, they are small actuators and deliver a few inch-pounds of torque to the largest one and can provide millions of inch-pounds of torque or even more. Furthermore, they have a cylinder that is coupled with some mechanism that switches the linear motion and changes it to quarter-turn motion that is necessary for valve operation. Not just that, but they also have an additional opposing spring that has positive shut-down in emergencies.
2. Pneumatic and hydraulic actuators (fluid power) – multi-turn
Now coming to multi-turn valve actuators, they help in operating a linear-type, valve-like gate valve, or a globe valve. People don’t usually use electric actuators for this purpose, but pneumatic and hydraulic actuators are a viable option for applications where electricity isn’t readily available.
3. Electric valve actuators – multi-turn
They are the most common type of valve actuator, and you will see them mostly everywhere, they are also very dependable. They are capable of swiftly operating some of the largest valves and you can power them with the help of a single or three-phase electric motor and are an amalgamation of gears and spurs. Moreover, they also gear, and spur drive a stem nut, and engage the stem of the valve to open or close it.
4. Electric valve actuators – quarter-turn
Its design is similar to the multi-turn electric actuator; the primary difference is that the final element is placed in one quadrant and offers 90 degrees of rotation. In a type like this, they are very compact and often used in smaller valves, because of low power requirements.
5. Manual actuators
With a manual valve actuator, you do not need an outside power source in order to move a valve to the desired position. Instead, what they use is a handwheel, chainwheel, lever, or declutchable mechanism that helps to drive a series of gears whose ratio results in a higher output torque when you compare it to the input (manual) torque. For several valves, manual operation is not a viable option, that is majorly because the application consists of valves in remote pipelines or the sheer force required for operation.
This guide intends to give you a better understanding of what is a valve actuator. In case we have missed something, please let us know.
