Skip to content Menu

You are here:

Application Newsletter 08/2017

Continuous dust monitoring with AirSafe

Avoidance of Ex areas during storage and monitoring of brown coal dust


A producer of dry mortar needs dry sand and trass for the production process. Both materials are dried in a hot gas heater at a temperature of 500 °C before they are admixed. The hot gas heater uses brown coal dust as combustion material. The brown coal dust, which is stored in a silo, is transported via a rotary valve in free fall to a distribution plate. From there it is blown by an airstream into the drying furnace.

The rotary valve and the distribution plate are located in the silo housing. Extreme dust formation, caused by a leakage, can cause an Ex zone in this area. Therefore the plant operator looks for a prompt possibility to detect dust formation. The plant is shut down when a safety threshold is reached, which prevents the development of an explosive atmosphere.

Process data

Customer: Manufacturer of construction material (Germany)
Product: Brown coal dust
Installation place: Silo housing
Function: Prevention of Ex areas caused by dust formation


The AirSafe monitors the dust concentration in the ambient air in control and process locations, silo areas, boiler houses and work stations. The device operates on the triboelectric measuring principle and has low maintenance requirements in comparison with optical methods. In this application the dust content in the ambient air of a silo housing is monitored. The AirSafe detects an increased dust concentration in case of a leakage and switches this part of the plant off, when a predefined limit level is reached. For this reason this part of the plant hasn’t to be protected as an Ex area.

Customer benefits

  • Avoidance of Ex areas
  • Safeguarding of the plant and avoidance of plant damages
  • Easy monitoring of remote parts of the plant