Sensor reading 2375

Sensors
1

I regularly see sensors that are reading a constant 2375. What does this mean?

  1. Is this a full scale reading for a Purple Air sensor and indicates a very high level of PM2.5 in the sensor area?
  2. Is this a indication of a malfunctioning sensor.
  3. Is this indicate of either of the above?
    Just wondered as this seems a odd number to come up on a regular basis and so seems it may be indicative of a special state for a sensor.
    .
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2

The sensor in my neighborhood (Bay Shore, MI) is having the same readings.

3

Most likely it is option 2, malfunctioning sensor.

That Bay Shore unit (#177241) has a bad channel B sensor. Compare to channel A, which has a more normal range. Looks like the problem started around June 5, during a high AQI event.

It would be interesting to know if a reboot or cleaning fixes the bad channel.

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4

As @dwhitemv mentioned, this is likely a malfunctioning sensor. If a piece of debris or an insect gets inside the laser counter and blocks the laser, it can cause it to jump to extremely high readings (2000+ AQI).

In this case, we recommend viewing our sensor maintenance article.

5

Hi Bob, if a sensor is reading a constant value that high, it’s likely due to debris caught in one or both of the particle counters, such as a dandelion seed or an insect/spider.

We have an algorithm that attempts to recognize this on the map and downgrade the bad channel. Downgrading one of the channels on a sensor still allows the data to be stored, but it will cause the readings from that channel to not show on the primary map icon for the sensor.

If this is a public sensor, you can get a link to it by clicking on the sensor and then copying the URL. Provide this and we’ll be happy to take a look at it. If we believe that the sensor is indeed providing a faulty reading, we will manually downgrade the bad channel and reach out to the purchaser of the sensor to offer assistance.

6

Hello Andrew,

Here is the link to the sensor in question Real-Time Air Quality Map | PurpleAir

I have attempted a reboot and used an air hose to blow it out, but it is still showing at a high reading. I read the guide to sensor maintenance and I will try those steps this evening.

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7

Let us know how that goes. Only blow air through channel B, as this is the affected laser counter. Channel A appears to match nearby sensor readings. Channel B is the laser counter closest to the USB port.

In the meantime, I’ve downgraded channel B, so only the channel A reading will appear on the primary map icon. Once you’ve got the sensor reading normally again, we’ll remove the downgrade.

If you run into any issues, please reach out. We’re here to assist.

8

Andrew - unplugged the monitor this morning and vacuumed it out for a few minutes. Plugged it back in and it doesn’t seem to have solved the issue with channel B. Is there anything else that we can do?

9

Hi Christopher, please send an email to contact@purpleair.com with your shipping address, and we will send you replacement laser counters. Reference this thread in your email.