Radio frequency based torque transducers

News Editor
TorqSense transducers lend themselves to test rig uses because they are non-contact measuring devices

To analyse the long term performance and reliability of hard working valves and pumps, Manchester-based Bifold Group has adopted radio frequency based torque transducers from Sensor Technology
for two of its specialist test rigs.

When Bifold wanted to assess the effects of wear on its long-life valves they set about designing a special test rig. Engineer Andrew Laverick recalls: “We wanted to measure the power required to operate the valve to see how it changed over time and with long term use. It was clear that the best way to do this was to measure the torque input over an extended period.”

“We were open to any design concept for the test rig, but soon found ourselves gravitating towards a TorqSense solution because the Sensor Technology engineers were so helpful and really knowledgeable about test rigs.”

TorqSense transducers lend themselves to test rig uses because they are non-contact measuring devices. Attached to the surface of the transducer shaft are two Surface Acoustic Wave (SAW) devices, when torque is applied to the shaft the SAWs react to the applied strain and change their output. The SAW devices are interrogated wirelessly using an RF couple, which passes the SAW data to and from the electronics inside the body of the transducer.

Sensor Technology’s Mark Ingham explains: “All you have to do is set up a TorqSense transducer in the test rig and fire it up. The SAW frequencies reflected back are distorted in proportion to the twist in the test piece, which in turn is proportional to the level of torque. We have some clever electronics to analyse the returning wave and feed out torque values to a computer screen.

“TorqSense has been used on many test rigs over the years and I was delighted to hear the Bifold engineers say how easy it is to use and how robust the software is.”

Laverick again: “As a test engineer you are almost resigned to long set up procedures and software that falls over at the drop of a hat. But Sensor Technology has designed these problems out of their TorqSense equipment, with the result that we were able to complete our long term test procedures with the minimum amount of fuss and heartache and well within the allotted time schedule.”

In fact Bifold has since bought a second TorqSense which is being fitted to a new test rig used to assess the performance of mission critical chemical injection pumps, as used at oil and gas wellheads and on process pipelines.

“This project is proceeding well,” says Laverick, “and is allowing us to further develop our abilities to quickly provide bespoke equipment for ultra demanding applications, safe in the knowledge that it will perform faultlessly over a long working life.”