30 May 2018

How can you get a valve positioner to work in excessive vibration – or other unsafe or poor locations?

At times, we have valve positioner applications that are affected by excessive vibration, temperatures, radiation, magnetic influence, and unsafe and/or poor locations. Addressing the root cause of the issue can be timely, expensive and sometimes deemed impossible by plant management.

At one power plant, I remember a situation where they had placed the valve too close to the boiler. Because of its proximity to the boiler, employees were hesitant to work on the valve. To make matters worse, the valve was placed in such a way that it made removing the positioner’s cover very difficult. So what options could the plant have taken? The plant could have either relocated the valve or dealt with the headaches…but, what if there was another option?

How do you overcome these “headaches”?

Essentially, you need precision control over the valve, but from a safe distance.

One solution is the Siemens SIPART PS2 Remote Mount Feature. With this solution, the user only needs one PS2 valve positioner with an EMC filter card and one PS2 detection unit, that houses a potentiometer and terminal board. The detection unit is installed on the valve using a standard mounting kit and is then connected to the PS2 with a cable. Once it is connected, you can remotely mount the PS2 in a safe location.

And, here’s option #2…

Another solution that I’d recommend is very similar to the Remote Mount Feature but utilizes different technology. This solution is our Non-Contacting Sensor (NCS) technology. The magnetic NCS is installed on the valve and then connected to a PS2, which is mounted at a safe distance. The sensor detects the current valve position using the giant magnetoresistance (GMR) effect and relays the change to the PS2.

To better explain the sensor technology, the NCS contains a magnetic field sensor that changes its electrical resistance in response to the immediate presence of a magnet. The installed magnet moves with the valve allowing the magnetic field sensor to detect movement and change its resistance.

This feature is particularly useful in extreme vibration applications where it helps avoid constantly replacing positioners due to wear on the electro-mechanical position interfaces.

Want some help?

Both of these technologies are simple to understand, install and operate. They provide a unique opportunity to safely operate and control valves in difficult applications. Please reach out to me if you need help with these types of applications.

How do you handle difficult applications with your valve positioners?

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