In many workshops, installing ducts to remove fumes, sawdust or other airborne materials is essential to protect workers, equipment, products and the environment. Businesses depend on them to keep running efficiently and economically, and preferably with minimal intervention, especially from personnel who may not understand how they work.
In dust (and fume) collection systems, components called blast gates are used to focus the vacuum extraction pressure at key locations. This means they’re located as close to dust or fume generating machinery as possible. Other sensitive points on the extraction route can be similarly equipped with a ductwork blast gate damper.
Put the Wood in the Hole!
As with other kinds of gate, alas, people sometimes forget to close them properly. In a vacuum system this has several ramifications – the drop in pressure impairs both extraction and the energy efficiency of the vacuum system as a whole. The consequences include poorer throughput, increased energy consumption or even blockages and downtime to clean up the mess. This can be costly, or in the case of ventilation systems extracting hazardous fumes, even dangerous.
Sometimes the problem is that individuals at several locations try to adjust their gate without understanding that the vacuum pressure at one damper is usually dependent on the vacuum pressure at all the other dampers too – so to open one the others may need to be securely closed.
Larger systems have the power for several gates to be open at the same time, but may experience a different problem – they may require at least one blast gate to be open at all times and closing the wrong one could cause damage.
Most damper gates are manually operated with a simple thumb-screw (a typical one can be seen at http://www.dustspares.co.uk/Blast-Gate-Damper.html), but there are gates available powered by servos, pneumatics, or hydraulics. For some people, adding a gate closer can be an in-house or DIY job.
Inevitably there is some additional outlay on these gates and their control equipment, but they may incorporate other features that could influence your decision. For example, some dampers that vent externally incorporate burglar alarms, while others can be used to activate the vacuum system itself – so you can save on your energy bills by only running the system when a gate is opened.