A Guide to Gas Analyser Sensors

The system uses 2 gas sensors:

A consumable Oxygen Sensor, which depletes with a combined use and age wear. As soon as they are manufactured the chemical inside starts to react and continues to do so until it can no longer detect oxygen either WELL or QUICKLY.

The sensor's lifespan is an expected 12 months, but can go sooner if used tons or left running without purpose, or longer if properly capped and not used. 

However we can't give any guarantee and there are things to watch for. 

Gain Factors, and response time warnings. Gain Factors increase or decrease over time depending on how the sensor performs. A gain factor of 1.00 is 'no correction required' by software. The further away from 1.00 the more correction is required by the software to bring the sensor in line with the calibration gas and ambient air.

A permanent CO2 Sensor, which lasts forever if looked after correctly. This sensor uses IR light to pass through the gas and a mirror surface to reflect against. This sensor should remain 1.00, however there are two factors that may affect this.

Ambient air differs from expected; the software assumes an ambient air mix of 20.94% and 0.03% O2/CO2. If you have a small room, or you've had a bunch of folk in the room all breathing, this will increase CO2 in the air beyond the expected 0.03, and therefore the system will calibrate the sensor against slightly incorrect baseline values, which causes a rise in correction. 

We have a device which consistently monitors the real time ambient CO2 and adjusts the baseline figure in the software automatically (we are so far the only CPET device which does this!), and replaces the original Ambistik that monitors the Temperature, Pressure and Humidity. This would only be something we'd recommend upgrading to if you were consistently unable to expel old air and bring in fresh.

Another cause of rising CO2 is a dust intake into the system by having the device running without proper fitment of the tube sets, which filter the dust particles from entering the internal tubing and hitting the reflective surface, causing the sensor to perform poorly. 

If there is a rising correction in CO2, an intervention with the users is required to ensure that they know not to run the system at all without a patient and tube set. If it continues to rise it ends up requiring manufacturer repairs which wouldn't be covered under contract as it's not part failure it's 'misuse'.