The customer had questions regarding the life of the detectors that we have on their systems, and if some varieties have a shorter life than others, with the consideration that they are all in the same environment?

Also if our engineers carry replacement sensors to potentially avoid callouts in between scheduled calibrations if sensors are known to be coming to the end of their life – possibly saving them money on callouts and downtime as well as keeping technicians and engineers minds at rest who were unsure if it was safe to remain in the area?

This was taken on by our Engineering Manager Chris Byrne following a joint service visit with our Service Engineer John Sutcliffe. It was explained that different sensors do have different life spans, even in fresh air as for toxic and O2 they use electrochemical technology. For example, the oxygen sensor vs the NO2 sensor would differ, in this case 2 years against 4 years according to the data sheets.

This is because the sensors work on a 4-20mA output so with the NO2 sensor sitting at zero, this would give an expected output of 4mA but in the case of the Oxygen sensor that is looking for 20.9% this is already at over 18mA in normal condition. Therefore, like a battery cell this will deplete faster than the NO2.