scowens
Contributor
Just courious, what kind of life span are you all getting out of O2 sensors?
Any tricks to extending their life?
Thanks
Steve
Any tricks to extending their life?
Thanks
Steve
O2 Sensors
- Thread starter scowens
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usually less than a year - they are highly recommended (if not required) to have sensors replaced annually...I don't think I'd trust to try and extend it beyond that.
Make sure the flow rate is at the appropriate level - continually "blasting" can wear them out faster I've been told...
Make sure the flow rate is at the appropriate level - continually "blasting" can wear them out faster I've been told...
scowens:
I have 1 doing great service for 3 years. I would not use an old one in a rebreather circuit but for an analyzer as long as it calibrates in air and pure O2 the sensor should be OK.
O2 analyzers function through a chemical reaction. The o2 essentially creates a reaction that causes a small amount of electrical current to be generated. The higher the partial pressure of the O2 the faster the reaction and the greater the current.
The fact that they actually measure PO2 and not percentage of O2 is the reason that "blasting" them with air could potentially shorten their life. This is also the reason that they need to be calibrated and why there is usually a slight difference in readings between a sensor exposed to open air and one in operation where the 21% flowing across it is at a slightly higher pressure.
If you are talking about O2 analyzers in a rebreather, I would not get cheap and would follow what ever the mfg recommends in terms of maintenance and replacement.
If you are talking about O2 sensors for an O2 analyser used for Nitrox fills etc, then I would recommend getting a cap to fit over the end of the sensor. This seals off the sensor and after a few days to a week the O2 level inside the sensor falls to zero. This prevents any significant reaction from occuring. Otherwise without the cap, the reaction and current generation will continue 24/7 and sensor life will be seriously decreased.
How long a sensor will last exposed to air all the time depends on the sensor. The R-17 sensors my analyser uses are supposed to last 3 years when exposed constantly to air. So with a cap on it most of the time, I am expecting substantially longer life.
The fact that they actually measure PO2 and not percentage of O2 is the reason that "blasting" them with air could potentially shorten their life. This is also the reason that they need to be calibrated and why there is usually a slight difference in readings between a sensor exposed to open air and one in operation where the 21% flowing across it is at a slightly higher pressure.
If you are talking about O2 analyzers in a rebreather, I would not get cheap and would follow what ever the mfg recommends in terms of maintenance and replacement.
If you are talking about O2 sensors for an O2 analyser used for Nitrox fills etc, then I would recommend getting a cap to fit over the end of the sensor. This seals off the sensor and after a few days to a week the O2 level inside the sensor falls to zero. This prevents any significant reaction from occuring. Otherwise without the cap, the reaction and current generation will continue 24/7 and sensor life will be seriously decreased.
How long a sensor will last exposed to air all the time depends on the sensor. The R-17 sensors my analyser uses are supposed to last 3 years when exposed constantly to air. So with a cap on it most of the time, I am expecting substantially longer life.
One thing note adding..DA Aquamaster:
If the sensors sit in an inert media for a time, it takes a bit for them to "wake up".. Typically will be ok at the low end but high fo2 mixes will be wrong.. the best bet is to expose them to oxygen of a high mix for a few minutes then calibrate..
f you want to prove this to yourself.. calibrate a sensor in air, quickly hook it to a high fo2 mix get a reading then remove it immediately.. let the cell stand for a while then take a new measurement on the 100%... you will be surprised.... it will now most likely read several opercent higher than before.
.. caveat, if the sensors are old, they actually fail after being exposed to a high fo2 for too long, although around 100% its not that bad.. They recover after being left at normoxic ranges for a time..
If you are using the sensor every day to every few days, there is no real advantage to capping them. WHere it does pay off is on long layoffs over the winter months etc. So for the most part having to wake the sensor up is not as large a problem in normal operation as it would initially appear.
Also, with mixes up to about 50% I have not noticed any issues with accuracy after being capped for a while as long as an initial calibration is done with a tank of 21%. The slight pressure involved in the flow to sensor for a minutes or so seems to get things up and running nicely.
Also, with mixes up to about 50% I have not noticed any issues with accuracy after being capped for a while as long as an initial calibration is done with a tank of 21%. The slight pressure involved in the flow to sensor for a minutes or so seems to get things up and running nicely.
Yea, this is for a Nitrox Analyzer...couldn't afford the divorce lawer if I had a rebreather....although, ....nawwww
I have a VTI analyzer that used a VTI-580 sensor, replaced it with Oxycheqs replacement (no p/n listed on web page). Neither has lasted over a year. I'm happy with Oxycheq and have heard no negatives. I'm just wanting to see/hear/read what others are experiencing.
I keep my sensor (when not using) in a small zip lock bag, in a small dry box. So, it's not sitting out in the open. I use the included hose and (fitting/cup) that came with the analyzer that goes into the quick disconnect for my BS/ dry suit. I don't think I'm blasting air onto it.
FWIW my Oxycheq was purchased in Sept. of last year and died this a few weeks ago, so I guess I'm doing about par.
I'd be interested to see what's done to/with those sensors that last for 3 years.
Thanks all
Steve
I have a VTI analyzer that used a VTI-580 sensor, replaced it with Oxycheqs replacement (no p/n listed on web page). Neither has lasted over a year. I'm happy with Oxycheq and have heard no negatives. I'm just wanting to see/hear/read what others are experiencing.
I keep my sensor (when not using) in a small zip lock bag, in a small dry box. So, it's not sitting out in the open. I use the included hose and (fitting/cup) that came with the analyzer that goes into the quick disconnect for my BS/ dry suit. I don't think I'm blasting air onto it.
FWIW my Oxycheq was purchased in Sept. of last year and died this a few weeks ago, so I guess I'm doing about par.
I'd be interested to see what's done to/with those sensors that last for 3 years.
Thanks all
Steve
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