Sensors failing sooner than expected

Hi! we’re in Mexico City and deployed 18 sensor back in August 2022 and thru today we have experienced 7 failures of optical counters, 9 if counting repeats. We have investigated voltage variations to no avail. We suspect bad batch of hardware as we installed 2 Purple Air back in 2018 and they are working just fine under same area and operational conditions. Any ideas or suggestions? Anyone else experiencing similar problems? Thanks for your input! Jaime

Hi Jaime,
It sounds like your PurpleAir sensors have lasted about 4 years if installed in 2018.
In our experience, we have found that PurpleAir sensors can last up to 4 years or as little as 15 days.
One can replace the optical counters instead of the whole sensor. The procedure / video is shared in another community forum post.

Hi Jasmine.
Thanks for sharing your thoughts and experiences. I just want to add that back in 2017-2018 I installed 40 purple air in CA and they operated fine for about 3 years until I got my first failure. So I wasn’t expecting this rate of failure, therefore I’m suspicious of operating conditions, particularly electrical.

Thanks for the insight on the POC replacement, I’m familiar with this repair. Anyway I’ll check it out in case there is something new to learn.

BTW, if the sensor fails too soon (i.e. 15 days) you can exercise warranty replacement.

Have a great year.

Jaime Contreras

Hi Jaime,
I misread your 1st post.
I think 3 to 4 years is very good for PurpleAir sensors (particularly no internal part replacement).
Regarding the ones deployed in August 2022 - we haven’t fully documented it, but anecdotally have observed newer PurpleAir sensors aren’t as good as the older ones.

Another anecdote that is weather related: Recently, we had a very cold spell here. For example temperatures ranged from -2F to -14F (-26C) during the day. The cold spell lasted over 24 hours. At least 2 of our PurpleAir sensors have not recovered and are now stuck at reporting high (>1000) PM2.5 values (Channel B for both).

Our sensor failed at just less than 2 years. We sent it back to PurpleAir to have it tested. It was not repairable, so we had to purchase a new one. We added power protection to the circuit, but are unsure that was the problem. We also wonder about a bad batch.

Thank you Jasmine and David for the added input.

Two of our sensor got stuck after a cold night of just 30 degF. But not affected the others. Is just weird.

BTW, we repaired 6 PA replacing POC-A , and always was the Channel A that diverted, stopped or failed. I wonder if this is per electronic design . I don’t think is coincidence. David, please let me know if the surge protection helps out, this might be the solucion but at an added cost.

Take care.

here in Pennsylvania we have plenty of sub-30 degree Fahrenheit days without failure. If it was the cold I think we’d see many sensors across the U.S. failing. It sounds like it may be more electrical.