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​Fixed Gas Detection - Case Study

​Fixed Gas Detection - Case Study

22nd Jun 2020

What was the problem/challenge that the customer had?

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.

Also, when the NO2 Sensor sent our system into amber ‘alarm’ status would it be difficult to predict how much life remained in the sensor before it reached ‘red’ alarm status?

Again, yes this would be difficult to predict. At the service interval the Engineer normally gets a ‘feel’ for the sensor’s suitability due to its response time when calibration gas is applied and the pre calibration response reading. This however will not take into account any background target gas or indeed a large unexpected release. The sensor will of course work, but as stated above will deplete faster than if it was sat in ambient conditions.

What did we do to solve/overcome it?

A sensor exchange programme was offered to our customer on a rolling basis so as a starting point, all the sensor serial numbers were required to establish the date of manufacture, this could result in some if not all of the sensors being replaced initially.

If we then look at the bi-annual service regime as it stands, we could possibly implement a sensor exchange programme. So, for the sensors with 2 year life expectancy we could calibrate as normal for the first 3 visits (1 Year 6 Months) and then swap out on the 4th visit, then continue the calibrations 5th, 6th and 7th visit, then doing a total system sensor exchange/calibration on the 8th visit.

What was that solution? And benefits of the service provided/ monitor/system installed?

The solution was the above offering as it will overcome the customers concerns regarding downtime, callouts and their Engineers confidence in the systems that keep them and their business safe. It maintains the current system in place without the need for a new offering and it will also enable Point Safety to continue to provide professional service going forward.