Valve positioners suitable for SIL 2 applications

Paul Boughton
The Industry Automation division of Siemens is expanding its positioner portfolio by introducing a rugged new device that is said to be simple and easy to handle. Known as the Sitrans VP300 positioner, this product is designed for use in the paper, mining and oil and gas industries and was developed according to SIL (safety integrity level) guidelines. Siemens says the Sitrans VP300 is the first positioner on the market to feature SIL-certified partial stroke testing (PST). Air exhausting in the single-acting device is SIL 2 rated.

Both the single-acting and double-acting versions of the positioner feature aluminium housings with high protection to IP66/NEMA 4x and are especially resistant to vibrations. The devices can be used in applications down to -40 degrees C and can even operate in damp air that is contaminated with oil or particles.

A rugged mechanical Opos interface connection can be used for fast and simple installation of the Sitrans VP300. Only two screws are required on the front of the positioner to attach it to the drive. The 'blocking function' enabled by the drive and installation set facilitates replacement of the positioner during operation. Another new feature is the contact-free position detection that works according to the giant magnetoresistance (GMR) principle and makes the measurements particularly resistant to magnetic fields and temperature fluctuations. Since only one magnet is required, installation is quick and easy, as the Sitrans VP300 has a travel distance of up to 150mm and can be rotated by up to 120 degrees.

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