When do I need to recalibrate or replace my Clarity Node-S?

Over time, your devices may need recalibration or replacement, whether you ran a custom collocation-based calibration or you're relying on the preset Global Calibrations. This article explains how to know, and the usual reasons it happens.

So you know: For background on why calibration matters in the first place, see what calibration is and why it matters.

How to tell: long-term collocation

The best way to know whether a recalibration or replacement is needed is to keep an ongoing collocation with a well-maintained reference monitor near your deployment region. Beyond the initial calibration, this site lets you track how your Node-S performs against the reference over time.

If the reference site's data is publicly available, you can compare performance over time right in the Dashboard, see comparing your collocated device to a reference monitor. A significant change in performance there is the signal to start a conversation about whether to recalibrate or replace, depending on your project's needs.

Reasons you might recalibrate

Both Global and custom calibrations try to capture as much environmental and pollutant variability as possible, but a device may still need recalibration because of:

• Extreme environmental conditions: the further conditions stray from those during calibration, the worse a sensor performs. This is especially true of the electrochemical NO₂ sensor.
• Unusual pollutant composition: performance drops when the pollutant mix differs from calibration conditions. This matters most for particulate matter, since sources change through the year (wood burning in winter, biomass burning, wildfire smoke).
• Sensor drift: sensors drift gradually as they age.

When to recalibrate is an active area of work at Clarity and across the sensor field, so reach out to support@clarity.io and we're happy to talk it through.

Reasons you might replace a device

Clarity devices are built to run reliably in harsh conditions and are expected to last over three years. Occasionally, though, a replacement is needed:

• Hardware failures: key components like the solar panel and battery system or the wireless communication system can occasionally malfunction before their expected lifespan, though this is infrequent.
• Sensor failures: sensors are generally durable but can fail early. The particulate matter sensor's optical path can be blocked by spiderwebs or pollen; the NO₂ sensor can experience electrolyte leakage from rapid temperature and humidity swings.

To catch issues early, check your devices' operational status on the Dashboard regularly. If you spot a problem or think you need a replacement, contact support@clarity.io.

What's next

• Compare your collocated device to a reference monitor.
• Check which calibration a device uses.
• Check your device's operational status and alarms.