K 2013: Dynisco's innovative Vertex pressure sensor delivers on its promise

Düsseldorf - In a marked departure from traditional sensor technology, Dynisco's Vertex pressure sensor for plastics extrusion applications, which is making its trade show debut here at K, has done away with the need for sensing with the help of mechanical structures or fill media. Instead, the Vertex offers direct sensing at the tip.

Michael Swanton, sales manager EMEA at Dynisco Europe GmbH, explained: "A common fill medium for pressure sensors was mercury. Because of environmental issues - the use of mercury has already been banned in Sweden, for example - we were exploring alternative technologies. Moreover, what we were hearing from our customers was that they wanted direct sensing instead of capillary tubing that transmitted the media pressure to the strain gage sensor, which led to the development of the Vertex."

Obviously, direct sensing means faster response and better control, says Swanton. This demand faster sensing measurements, and so the Vertex sensor is many times faster than traditional sensors. Accuracy, as defined under the ISA-S37.1 standard, is pegged at ±0.25% full scale over standard pressure ranges of 1500, 3000, 5000, 7500 or 10,000psi.

The Vertex uses capacitance to measure the movement of the sensing element, called the diaphragm. The technology has been patented.

"The diaphragm is a relatively delicate part of the device," Swanton said. "In the Vertex, the diaphragm is much thicker than in other sensors, which considerably improves the robustness and extends the service life of the sensor."

The Vertex diaphragm is made of Inconel 718 alloy, which provides a higher level of corrosion resistance than stainless steel, and coated for added protection against abrasion. The sensor wall structure has also been fortified to handle side stresses.

Swanton: "This proprietary coating allows it to stand up to the conditions under which it is used much better. As a matter of fact, we're confident enough about the durability to offer customers a 4-year warranty on the sensor. And it's a drop-in replacement, so it's easy to make the switch to the new technology."

According to Swanton, another major differentiating feature is the temperature range that the sensor can handle. "While there are alternative non-fill technologies, in most cases, getting up to 425oC is a challenge. PEEK, for example, typically runs at 390 -400oC, which is no problem for the Vertex."

Thanks to direct sensing technology, the sensor contains no mercury, no NaK, no oil, no Gallium - in fact, there is no fill material of any kind. There is nothing to leak and no disposal concerns. It is also fully compliant with the European RoHS directive. With a longer design life, Vertex also contributes to waste-stream reduction. 

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