In workshops and factories that have dust extraction systems installed, you will often have several machines feeding into the same ducts. In order to control the airflows and ensure that the system is properly efficient blast gate dampers are used.
Dust in the workplace is hazardous, so proper extraction systems are essential – http://www.hse.gov.uk/pubns/cis69.pdf. Not only that, they need to work effectively. Using blast gate dampers gives better control, ensuring that machines creating dust at any particular time receive priority.
How they work
Blast gate dampers control the flow of air from different machines into the system. Ducts can be shut off to maximise airflow at a specific machine, this would typically be needed on a system where the airflow is insufficient to support all of the extraction points at the same time.
The dampers themselves have a moving flap that can be secured in different positions. They are usually made of aluminium and fitted to the ventilation system with ductwork parts from a supplier such as https://www.dustspares.co.uk/ductwork-parts/ ensuring an effective seal at any joints. Dampers can be fitted to a system when it’s first installed, but their design makes it relatively easy to retro-fit them later if the system requires it.
Manual or automatic
Blast gate dampers can be operated either manually or automatically. With a manual damper the flap is moved into position and fixed in place with a thumbscrew. This allows the flap to be moved to any position so that you can restrict the airflow or shut it off completely.
Automated dampers are usually operated pneumatically. This uses an electric solenoid to control compressed air fed to pneumatic cylinders that open and close the flaps. A pneumatic control kit can be used to operate a damper locally from close to the machine, or they can be operated from a central control panel that allows the operation of the entire system from a single point.
It’s also possible to link a pneumatic damper to the machine it serves so that, for example, each time a circular saw is switched on the damper feeding its extraction system is opened automatically, allowing dust to be carried away, and is then closed again when it’s switched off. This reduces the risk of operators forgetting to set the damper correctly before starting to use the machine.