Piece of junk collected from a rubbish skip turns out to be 50 year-old pressure sensor, still within original specification
Student Tim Hands spotted a glint of steel in a rubbish skip, outside the Cambridge University engineering department, that turned out to be an old pressure sensor.
Thinking that it might be useful, he put the sensor into a drawer.
Years later, working for engine emission control specialist Cambustion, an independent company with close links with Cambridge University engineering department, Hands needed a sensor for a project and remembered the one he had found in the skip.
The only identification on the sensor was 'SLM 425 Swiss' so Cambustion asked Swiss sensor manufacturer Kistler Instruments if they could supply a cable to fit.
Kistler recognised the sensor as one it had sold in 1954 and, while it could supply a suitable cable, the opportunity to acquire an SLM sensor was too good to miss.
Cambustion was happy to accept the offer of one of Kistler's latest miniature M5 pressure sensors in exchange for the SLM.
On its return to Switzerland, the fifty year-old sensor was put through its paces in the Kistler calibration laboratory where it was found to be in good working order.
Isolation was well within the original specification and re-calibration proved to be as simple today as it was in 1954.
Although no one would expect a sensor to be guaranteed for fifty years, Kistler says this does show that its sensors should not be consigned to the rubbish bin too early.
