Bofa Self Extinguishing Inline Pre Filter.

In the rare event that a burning ember or spark is drawn into the fume extraction unit, there is the possibility that debris in the filters could ignite. Although any resultant fire would typically be retained within the fume extraction unit, this would cause significant damage and in extreme circumstances the risk may extend beyond the extraction unit. For processes where such risks have been identified, additional protection in the form of an in line firebox is an additional precaution.

Operation.
The extinguisher activating coil will discharge the powder if the temperature on its surface exceeds 63º C. The extinguisher unit can also be used to switch a (13A) supply, for example; the extraction unit.

How the fire extinguisher works.
The fire extinguisher discharge mechanism is a special plastic hose, coiled around the inside of the filter box lid. This dispenses the fire retardant in the event of a fire, protecting the fume extractor and other areas nearby.

The temperature sensor.
As a secondary and extra safety measure, the filter unit has a temperature sensor that is positioned in the air flow path.

This sensor can be set by the user to measure the temperature of the air flow in case a fire develops in the ducts before reaching the main body of the unit.

For example if a fire were to develop in the pipe work leading to the filter unit, the temperature sensor would sense this and disable the contactor and extraction unit from drawing in air, so preventing the fire from continuing.in body of the unit.