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Phase 1 Alerts (yellow)

Phase 1 alerts are triggered only after the sensor detects a significant decline in air quality within the microclimate around the sensor.

A decline in Air Quality is indicated by an increase in the IAQ value. This decline triggers a Phase 1 fire detection process and is done anonymously without notifying users. It involves the following four steps:

  1. Sensor checks the air quality every 60 seconds.

  2. If air quality remains unchanged, send data packets containing air measurements every 2 hours.

  3. If the air quality deteriorates over a set timeframe, trigger a Phase 1 alert.


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.

Sensor checks air quality every 60 seconds

Once every 60 seconds, the sensor uses an algorithm to check the Air Quality in the microclimate within range of a sensor.

Check air quality every 60 seconds

Check air quality every 60 seconds

Data packets sent to Silvanet Cloud every two hours

As long as the sensor detects Normal Air which means the baseline IAQ determined during calibration remains stable, it sends data packets to the Silvanet Cloud every two hours.

These data packets contain the current air pressure, temperature and humidity in the environment within range of the sensor. This data appears in the Site Management app.

Send data packets every 2 hours

Send data packets to Silvanet Cloud every 2 hours

Deterioration in air quality triggers Phase 1 alert

If the Air Quality has significantly deteriorated (IAQ change > 50) within a short period of time (using a sliding window of 5 minutes), then the gas sensor issues a Phase 1 alert. This alert is sent to the Silvanet Cloud. Clients do not receive this alert but is used internally to determine why the sensor reacted.

A Phase 1 alert triggers the Phase 2 detection process to determine if the sensor has detected a fire.

Deterioration in air quality

Deterioration in air quality

See also

For more information about gas scans, see Gas Scans and Fire Models. For details about the Phase 2 detection process, see Phase 2 Alerts (Red).