It is an ideal collector for the collection of highly explosive dusts since it removes the dust from the oxygen rich airborne environment, the water eliminates any sources of combustion, and the encapsulation of the dust in the water prevents the formation of a dispersed explosive dust cloud.
These are the collectors of choice for collecting the explosive dust formed when working light metals such as aluminium, titanium and magnesium. While there are ways to handle some explosive dusts in dry fabric dust collectors (but not light metals), the solutions required often cost more than the original dust collector.
Wet hydrostatic precipitators can handle heavy inlet air dust loads (up to 10 grains per cubic foot).
Wet centrifugal dust collectors inject controlled sprays of water into the air entering the device and through a combination of mixing, impaction and centrifugal force, cause the particulate and water to mix and then be separated from the airstream. Such collectors use specially designed blades to enhance this process and increase efficiency.
An important feature of the wet centrifugal dust collector is that it is both an air moving device AND a dust collector. This negates the need for a separate fan with all the attendant cost savings. It also means that the product has a small footprint and will fit into spaces where other types of dust collector will not.
Wet centrifugal dust collectors are designed to handle inlet air dust loads up to 2 grains per cubic foot.
High pressure wet venturi dust collectors are the preferred wet collector for difficult wet, sticky, oily or self-combusting dusts when very high efficiencies on small and sub-micron particulate are desired. The contaminated air is forced through a narrow venturi throat at very high velocity where it is mixed with a water spray. The resultant water-particulate mixture is then removed using a cyclonic separator.
The disadvantages of the wet venturi dust collector are the quantities of water required and the high energy needed to force the air through the venturi. However, it is often the only dust collector that can be effectively used for some applications. .
Electrostatic precipitators use electrostatic forces to collect the particulate contained in an airstream. There are two main types: high-voltage single state precipitators (Cottrell type) which use high voltage (40,000–70,000 volts) DC discharge electrodes; and low-voltage dual state precipitators (Penny type) which use a much lower voltage (a 13,000-15,000 volt DC supply with intermediate supply of 7,500).
The large Cottrell-style collectors are typically used in large power plant applications but have been losing ground in recent times to media collectors due to high initial cost. The smaller Penny style collectors are excellent for removing smoke and oily particulate from the airstream in industrial applications but have also lost ground to media filters, again because of higher initial cost.
The advantages of electrostatic precipitators are their high removal efficiency and low energy usage because the open plate design presents almost no barrier to airflow.
Cyclones and drop-out boxes are often used as pre-cleaners to eliminate the larger particulate and much of the mass from an airstream ahead of a high efficiency dust collector. Cyclones induce a rotational centrifugal force into the airstream which causes the heavier particulate to separate from the lighter air. Drop out boxes use change of direction and slowing of the air velocity to cause the heavier particulate to drop out of the airstream.
Cyclones may remove between 70% and 80% of the mass of particulate in the airstream. They are ineffective in removing small size particulate.