Are air dampers needed for dust extraction systems? (Hint: YES, there are)
Ventilation dampers are used in dust extraction systems to adjust and control airflow into particular duct branches. A dust extraction system must be equipped with guillotine dampers (manual or automatic) installed close to each extraction point of the transported material, e.g. sawdust, to balance the whole system. Why? An unbalanced dust extraction system could result in too much air being extracted from one area, while not enough airflow is provided to extract dust in another area. The air dampers are also used to separate sections of the ductwork which are not currently operated, thus optimising the operation of the entire system. If properly designed and installed, a dust extraction system should “cooperate” with other extraction and filtration equipment. However, if no airflow regulation is provided, this can adversely affect the performance of the entire system. Don't forget to include dampers when designing a dust extraction system!
Sliding vs. shut-off dampers
Two types of dampers are used in dust extraction systems – sliding gate and shut-off dampers. Both types of dampers play a specific role in the ventilation system and they are not interchangeable. When and where to install them? In short: shut-off dampers are installed (and should only be installed) in a system returning clear air to rooms while sliding dampers (gate valves) are used in an extraction system, i.e. one for transporting polluted air.
Backdraft air dampers DAOSQT and closing dampers DATQT can be installed only
in the ductwork branches that transport clean air.
Installing a shut-off damper in a dust extraction line, i.e. the ductwork which transports material, e.g. sawdust and wood dust, will cause the material to accumulate on the damper's blades, and then block the system. These dampers are used to open and close duct branches so that the airflow is directed only to those machines, which are in operation. The operation of the sliding damper is quite simple: the gate slides up and down to open or close the pipeline. Sliding gate dampers have a fully openable planar surface, without any pins or edges that could obstruct the conveyance of media through a pipeline, thus preventing the forming of blockages inside the dust extraction system. Due to its design, such a damper occupies much more space around the pipeline, as the gate protrudes well beyond its outline, which needs to be taken into account when designing the system.
Which guillotine damper should I choose – a manual or an automatic one?
Guillotine dampers are available in two versions: manual and automatic (with an actuator). Guillotine dampers optimise the negative pressure and flow, thus increasing the efficiency of the dust extraction system, and the flow control helps you to save energy and reduce costs. Both types of guillotine dampers fulfil this role – the difference lies in the level of optimisation and comfort of use.
Automatic sliding dampers are supplied with a solenoid valve.
The use of automatic sliding dampers is simply more practical since you can put together the automatic control with machinery operation, e.g. grinders, saws, etc., providing precise and accurate air distribution to specific machines, which translates into higher machine efficiency, less noise, lower energy consumption due to increased plant efficiency, which in turn results in lower operating costs. When installing automatic sliding dampers, there is no room for human error, e.g. if the operator forgets to close the dampers, this can lead to a reduction in the efficiency of the plant, or, in the worst-case scenario, to the clogging of the system.
The proper operation of manual sliding dampers in a dust extraction system depends on the discipline of the machine operator, because, as the very name suggests, the operator must close or open the damper manually. Thanks to the use of dampers with a pneumatic actuator, there is no need to oversize machines. Thanks to the more efficient and properly adjusted system, there is no need to select equipment with an increased capacity to compensate for the inefficiency of the system. In turn, the greater the capacity of the installed device, the higher the level of noise and power consumption.
Gate dampers are used to open and close duct branches so that
the airflow is directed only to those machines, which are in operation.
In summary, when choosing between a manual or automatic sliding damper, you must realistically analyse the complexity of your dust extraction system, especially the size of your stock of machinery. We recommend installing the sliding dampers with an actuator when your machine park includes more than 2–3 machines in order to design a more efficient system.