Once your sensor has been in service at the installation location, it becomes exposed to foreign contaminants. We expect the sensor to contact airborne particulate matter. But undesirable contaminants may impede the function of the sensor.
We do not recommend a regular cleaning schedule for PurpleAir sensors, and no preventive maintenance is required. If one of the laser counters is not reporting as expected, is downgraded, reporting high, not working, or spikes erratically, then it is possible that one of the laser counters in your sensor has become congested with debris, an insect, or a spider.
If necessary, clean out the laser counters: place a shop vacuum or traditional vacuum hose on the bottom of the sensor for 2-3 minutes. Clear out the laser counter with canned compressed air if further cleaning is necessary. For PA-II and PA-II-SD sensors, focus on the four collinear holes on each laser counter (see image below). For PA-I edition sensors, focus on the rectangular hole on the side opposite the fan. For the PA-II-FLEX, focus on the rounded rectangular hole on each laser counter.
For PA-II edition sensors, the A channel is the laser counter farthest from the USB port. The B channel is the laser counter closest to the USB port.
Note that an increased airflow speed can cause the fan to spin at a much higher rate than recommended, which can damage the laser counter.
If attempts to clean the device prove unsuccessful, the laser counters in your device may need replacing. Laser counters are purchasable through our online store. Make sure to select the correct version of laser counters for your device. The laser counters for PA-II edition sensors come in a pair, while the PA-I-Indoor laser counter comes individually. All Plantower laser counters are pre-tested in PurpleAir test chambers before being sold.
The following videos will guide you on completing the laser counter replacement processes:
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PA-I: PA-I-Indoor Laser Counter Replacement Video.mp4 - Google Drive
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PA-II or PA-II-SD: PA-II-SD Laser Counter Replacement.mp4 - Google Drive
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PurpleAir Flex: PA-II-FLEX Laser Counter Replacement.mp4 - Google Drive
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PurpleAir Zen: PurpleAir Zen Laser Counter Replacement.mp4 - Google Drive
The PA-II laser counter replacement process is nearly identical to the PA-II-SD. Any sections that mention the SD logger or SD card can be dismissed, as the PA-II does not utilize an SD card.
If PurpleAir has manually downgraded a channel on your device, you will need to contact us to remove the downgrade.
Learn More
Learn more about calibrating PurpleAir sensors .
Learn more about downgraded channels.