How to Select the Right Valve Positioner for Your Application
A valve positioner may look like a small part of a control valve assembly, but a poor match can cause unstable movement, slow response, difficult commissioning, or avoidable replacement costs. Only provide series name is not enough when choosing a valve postioner. You also need to check the actuator, valve travel, control signal, air supply, mounting arrangement, and certification requirements.
This guide from Wenzhou Conch Electric Co.,Ltd explains what to confirm before choosing a pneumatic, electro-pneumatic, or smart valve positioner. It also highlights practical differences among Fisher, Siemens, and ABB solutions.
What Does a Valve Positioner Do?
A valve positioner makes sure a control valve reaches the opening requested by the control system. It receives a command—often a 4–20 mA or pneumatic signal—checks the valve’s actual position, and adjusts the air pressure sent to the actuator.
This continuous correction helps the valve hold the required position even when stem friction, packing resistance, pressure changes, or other process conditions affect its movement. Smart positioners can also provide setup tools, alarms, and diagnostic information, depending on the model and communication option.
Information to Confirm Before Selecting a Valve Positioner
Before asking for a quotation, collect the information below. A few clear photos of the valve, actuator, existing positioner, and nameplates can help us do decision quickly.
1. Valve and Actuator Type
Start with the valve motion. A globe or diaphragm control valve usually has linear travel, while a ball, butterfly, or plug valve usually rotates through an angle. The positioner and feedback mechanism must suit that motion. Also confirm the actuator make, model, stem or shaft arrangement, and available mounting interface.
2. Single-Acting or Double-Acting Actuator
A single-acting actuator uses air in one direction and a spring in the other. A double-acting actuator uses air pressure in both directions. The positioner must have the correct pneumatic output configuration. If you are unsure, check the actuator nameplate, air ports, pneumatic diagram, or the original installation.
3. Input Signal and Communication Protocol
Confirm how the control system will communicate with the positioner. Common requirements include a 4–20 mA analog signal, HART communication, fieldbus options, or a pneumatic input. Do not assume that every unit within the same product family supports the same protocol.
4. Fail-Safe Action
Decide what the valve should do if the electrical signal or air supply is lost: fail open, fail closed, or remain in place. This behavior depends on the actuator, spring arrangement, tubing, and positioner configuration—not on the positioner name alone.
5. Air Supply Pressure and Air Quality
The available supply pressure must fall within the positioner and actuator limits and still provide enough force to move the valve under operating conditions. Instrument air should also meet the manufacturer’s requirements for cleanliness, dryness, and oil content. Wet or contaminated air can cause sticking and premature wear.
6. Hazardous-Area Certification
If the valve is installed in a hazardous area, confirm the exact protection method, gas or dust group, temperature class, and local approval required for the site. A model family may be offered in several certified versions, so the full order code and certificate marking matter.
7. Environmental Conditions
Check ambient temperature, humidity, dust, washdown exposure, vibration, corrosion risk, and whether the installation is indoors or outdoors. The enclosure material and ingress-protection rating should match the actual environment.
8. Diagnostics and Maintenance Requirements
Basic applications may only need reliable positioning and local calibration. Critical control loops may benefit from valve-signature testing, travel monitoring, friction alerts, event history, or remote diagnostics. Choose the level of diagnostics your maintenance team can actually use.
Quick Valve Positioner Selection Checklist
- Valve manufacturer, model, and valve type
- Actuator manufacturer and model
- Linear or rotary motion
- Single-acting or double-acting operation
- Valve travel or rotation angle
- Input signal and communication protocol
- Available air supply pressure
- Required fail-safe action
- Hazardous-area certification
- Ambient and site conditions
- Required diagnostics
- Existing positioner model and full order code, if this is a replacement
Comparison of Common Smart Valve Positioners
The following overview is for reference only and is not a substitute for consulting the complete model code and data sheet. Specific features and certifications vary depending on the configuration.
| Selection factor | Fisher FIELDVUE DVC6200 | Siemens SIPART PS2 | ABB TZIDC |
| Often considered for | Applications where valve diagnostics and asset information are important | Flexible linear or rotary installations, including sites focused on low air consumption | General industrial control applications with straightforward setup and operation |
| Actuator application | Depends on configuration, feedback arrangement, and mounting | Linear and rotary | Linear and rotary |
| Communication | Depends on selected model and option | Depends on selected model and option | Depends on selected model and option |
| Selection note | Confirm the full model code and mounting hardware | Confirm enclosure, protocol, and actuator configuration | Confirm action type, communication, and certification |
Common Valve Positioner Selection Mistakes
- Ordering by Series Name Only
A request for “DVC6200,” “SIPART PS2” or “TZIDC” does not identify the complete configuration. Products within the same family may differ in pneumatic action, communication, enclosure, certification, diagnostics and accessories. A full model code or application details are needed for an accurate quotation.
- Assuming the Mounting Kit Is Included
The positioner, bracket, feedback lever, shaft adapter and magnetic feedback components are not always supplied as one package. State whether a mounting kit is required and provide actuator details before ordering.
- Confusing an IP Rating with Explosion Protection
A weather-resistant enclosure is not automatically suitable for a hazardous area. Confirm both the ingress-protection requirement and the applicable explosion-protection certification.
- Forgetting the Actuator Action
Single-acting and double-acting positioners have different pneumatic arrangements. If the actuator action is missing from an enquiry, the supplier may be unable to confirm the correct configuration.
- Choosing a Replacement by Appearance
Two positioners may look similar while using different input signals, pneumatic connections, mounting dimensions or feedback methods. Treat any cross-brand or newer-model replacement as a new compatibility check.
How to Select a Replacement Valve Positioner
For replacement projects, send the following information to your supplier or engineer:
- Clear photo of the existing positioner nameplate
- Complete model or order code
- Valve and actuator nameplate photos
- Wide-angle photos showing the mounting arrangement and tubing
- Input signal and communication requirement
- Single-acting or double-acting operation
- Air supply pressure
- Required hazardous-area certification
- Quantity
If the original model has been discontinued, these details make it much easier to evaluate a suitable replacement and identify any mounting changes.
Frequently Asked Questions
Can one valve positioner be used for both linear and rotary valves?
Some positioner families support both, but the feedback arrangement and mounting components are different. Compatibility must be checked for the specific actuator and installation.
How do I know whether my actuator is single-acting or double-acting?
Check the actuator nameplate, pneumatic schematic and air ports. A spring-return actuator with one controlled air connection is usually single-acting; a double-acting actuator is driven by air in both directions. If uncertain, send photos and the actuator model for confirmation.
Is an IP66 valve positioner explosion-proof?
No. IP ratings and explosion-proof certifications belong to different protection systems.
Can I replace an old positioner with a different brand?
Yes. But only after checking mounting, feedback travel, pneumatic connections, input signal, air supply, action type, fail-safe behavior, and certification. A new mounting kit or tubing change may be required.
What information is needed for a quotation?
The fastest way is to provide the complete model code, nameplate photos, valve and actuator details, mounting photos, signal type, air supply pressure, certification requirement, and quantity.
Need Help Selecting a Valve Positioner?
If you are not sure which configuration fits your application, send Wenzhou Conch Electric Co., Ltd. the valve and actuator model numbers, nameplate and mounting photos, input signal, air supply pressure, and hazardous-area requirements. Our team can help you check the required configuration and available options from Fisher, Siemens, ABB, and other major manufacturers.