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Detecting fires

Silvanet sensors use a gas sensor that is an AI-enabled low-power device that measures air pressure, temperature and humidity and detects gases such as Volatile Organic Compounds (VOCs) and carbon monoxide. This gas sensor uses a Dryad-developed algorithm to detect fires, even in their smoldering phase.


A smoldering fire is defined to be a slow, flameless combustion of a biomass material such as forest floor material, branches, leaves.

Calibration period

Using the Dryad-developed algorithm, the Silvanet sensor calibrates normal air around a Silvanet sensor.

The calibration period is approximately 14 days after deployment. During this period the sensor detects existing VOC compounds (such as diesel exhaust) to form a base "air quality". After this calibration period, the sensor is ready to detect any deviation from the normal air. If a deviation is detected, this triggers a process to determine if the deviation is, in fact, the result of gasses produced by the smoldering phase of a fire.

Verification consists of two phases described below.

Fire detection phases

The Silvanet sensor has two phases for detecting fires:

  • Phase 1: Yellow Warning
  • Phase 2: Red Alerts

Phase 1 (Yellow) Warnings

During a Phase I fire verification process, the sensors check the air quality index (AQI) once per minute.

If the air quality has significantly deteriorated within a short period of time (using a default sliding time window of 20 minutes), the sensors issue a Phase 1 or Yellow Warning. Phase 1 (yellow) warnings can be triggered by several events including fumes of car exhausts or other environmental triggers.

A Phase 1 alert means that the sensors have "smelled" something unusual. The sensitivity of the Phase 1 algorithm (threshold and sliding time window) can be configured remotely by Dryad’s support team.


In the future, Dryad is planning to enable self-configuration by customers using the Site Management app as well as an adaptive algorithm aiming to reduce the number of Yellow Warnings over time.

Phase 2 (Red) Alerts

When the sensor detects a Phase 1 (Yellow) alert, it automatically starts a gas scan which can take 1-3 minutes to complete.

During the gas scan, the sensor measures hydrogen, carbon monoxide and other volatile organic compounds. It uses a built-in Artificial Intelligence (AI) / Machine Learning (ML) model to compare the measurements with pre-trained models to reliably detect the gas composition typical for a wildfire.

If the AI determines that the gas detected is a fire, the sensor immediately sends a Phase 2 (Red) Alert. Models are pre-trained in the Dryad laboratory and can be fine-tuned / programmed specifically for the species of trees present in a particular deployment. Updated models can be remotely installed in the sensors by Dryad’s support team.

After the sensors have detected a fire, an email alert will be sent to the appropriate users. Additionally, in the Site Management app, a Fire Alert appears.


In the future, Dryad is planning to enable customers to update the ML models using the Site Management app.

See also

For more information about alerts, see Fire alerts.

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