Electrochemical cell H2S detectors maintenance

[ChrisAdam]

I work for a large offshore installations where we have more than 1800 H2S electrochemical H2S detectors of various models, there has been a long discussions on how these detectors should be maintained. Vendors always recommend replacing the sensors heads routinely every 2 to 3 years but some managers argue that this is only to sell us large quantity of sensors.

Can you share your experience with this kind of detectors, do you regularly replace the sensors heads or you follow a performance test schedule upon which you replace the sensor heads, what's your criteria for replacing the sensor head.

Regards,
Chris

 

[IRstuff]

From what I read, it would seem that it's a question of how much of a gambler you are. If you are referring to actual chemical solubility processes, then one can picture issues with electrolyte leakage, contamination, H2S contamination, moisture absorption, etc. If you have a robust means of verifying the integrity of the sensors, then you can certainly test them routinely and replace those that fail to meet their specifications.

TTFN
faq731-376

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[DRWeig]

Agree with IRstuff.

I was product manager for several brands of combustible and toxic gas sensors for a number of years.

Life of the electrochemical element in an otherwise clean atmosphere depends mostly on the total accumulated exposure the gas being sensed, H2S in your case. The other factors that IRstuff listed can play an important role, too, particularly if they are severe or frequent.

Our of our more thoughtful manufacturers recommended annual calibration at span with calibration check at zero and midpoint. If you can accomplish that within specs, it's probably good for another year. If your exposure to H2S can be classified as often or severe (subjective, I know), calibration at 6-month intervals is appropriate.

Of course, replacement after drenching, exposure to extreme heat or cold, oils, caustics, particulate matter, or really any liquid except for occasional condensation of clean water is probably required.

More importantly, check with your company's liability insurance carrier or any regulatory agencies that may govern your plant safety. Deviating from the manufactuer's recommendations may not be permitted by one or both of them.

Best to you,

Goober Dave

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