The control valve calibration procedure will depend on the positioner you have installed on your control valve. As the name suggests, the control valve positioner receives data from the controller, then sends pressure to the valve to move it up or down.
This article will guide you through the calibration procedure for a pneumatic control valve positioner. The same process can be applied in other cases but calibration procedures might differ slightly between vendors. If you are trying to calibrate a different device and feel unsure about what you are doing, give us a call and we will help you.
How to calibrate a pneumatic control valve positioner
If you have a pneumatic positioner receiving a signal between 3 and 15 psi, the control valve calibration procedure is entirely manual. For this discussion, we’ll use a Fisher pneumatic positioner and give you an overview of how to calibrate the control valve for it.
Setting up the control valve for calibration
- The first step is to check the operation cam: make sure that you have the right cam for your positioner and that it is installed correctly.
- Then, you need to check the feedback arm. You may need to follow certain steps to install the positioner on the valve, such as keeping the valve in 50 percent of the range when mounting the positioner.
- You’ll also need to confirm you have the air supply connected for enough working pressure and the positioner output is connected to the valve actuator.
Yes, lots of steps before the actual control valve calibration, but you must do them all for your procedure to work.
Pneumatic control valve positioner calibration
- To begin the control valve calibration, first, you need to supply 4 milliamps (mA) to set the zero position.
- Then, you’ll supply 20 mA and adjust the span using the flapper.
- When you finish the span adjustment, check the zero. You may need to do it again. You’ll go back and forth between zero and span until you have the correct travel.
- Last but not least, you need to ramp up and down the valve’s travel, using 4, 8, 12, 16 and 20 mA.
That covers the process of calibrating a pneumatic control valve positioner. If you still have questions, feel free to get in touch with our engineers.