Perfect Valve Positioners: How Valve Positioners Protect Your Tanks

You understand the importance of valves in your operation. But have you considered how important it is to use valve positioners in your application?

Valve positioners have been shown to improve control valve performance. There’s really no reason not to use them.

Keep reading to learn more about how valve positioners work and some of the benefits of using them with your control valves. 

What Are Valve Positioners?

Valve positioners are devices used to change (increase or decrease) the air load pressure that drives a control valve’s actuator. The goal is to ensure the valve’s stem reaches a position that is balanced to the output signal given by the process variable instrument controller.

They are usually mounted on either the top casing or side-yoke of a pneumatic actuator for stem control valves. When it comes to rotary control valves, they are usually near the end of the shaft. Valve positioners can give you more control over your valves.

Reasons for Using Valve Positioners

There are many good reasons to use valve positioners in your application. These are just a few of the top reasons to consider using valve positioners:

  • To use piston actuators with high air supply pressure
  • To use characteristic cams with rotary valves
  • For operation with higher number actuator bench-set ranges
  • Split ranging/ using one controller for two valves
  • For more range of flow variation
  • Overcoming seating friction with rotary valves
  • To compensate for imbalances with internal force
  • Faster venting and loading/faster speed of response to changes in process
  • Reduce effects from valve stem packing friction
  • To allow more distance between control valves and controllers

Types of Valve Positioners

There are three types of valve positioners. They each achieve the same function but use different means to do so.

The type that will work best for you depends on your application. Let’s break them down. 

Pneumatic Positioners

These rely on a pneumatic signal being supplied to the positioners. The valve positioners then translate the signal to the valve positioner and provide air pressure so that the actuator can move the valve. 

Analog I/P Positioners

These use electrical current instead of air for an input signal but otherwise achieve the same function as described above.

Smart/Digital Positioners

This positioner type works almost identically to analog I/P positioners. The main difference is that the electronic signal conversion is digital instead of analog.

There are three categories of digital positioners: digital non-communication, HART, and Fieldbus.

Purchasing Valve Positioners

Now that you know a little more about valve positioners, you may be interested in using them in your operation. It’s important to choose the best type of valve positioner for your application.

You can view our product selection here or you can contact us to learn more about the products we offer. We would love to provide you with more information to help you make the right choice for your industry.