Dust is a problem in any indoor space. It can be unsightly , can affect the respiratory lungs of the occupants . Most dusts are also a combustible hazard which require special handling of the dust. This includes special options on the dust collector which includes, explosion vents, suppression vents, no return isolation valves. Also good house keeping is a must to keep non captured dust to be cleaned periodically so compatible dusts are not left on surfaces. NFPA 68 has since 2007 required all dusts to be tested to determine explosiveness of the dust. If the dust is not explosive than the controls as stated above are not required on dust collectors, and on dust collectors under 8 cubic feet of the dirty side of the enclosure is exempt . Also one other exemption is the under 5000 cfm wood dust collector’s on wood dust are also exempt of controls on most instances. Last year 2021 NFPA 652 mandated all companies with dust collection systems to provide a Dust Hazards Analysis DHA . This is a complete analysis which includes the dust test and specific hazards analysis for that plant and operation. Typically done by a registered engineer and can costs from $ 6000 to $ 20,000 . The reason for these mandates is the explosions of dust in plants across the country. Please see enclosed e mail with Dust Hazards Analysis incorporate the full description.
That is why AAir Purification Systems designs, builds, tunes, and maintains top-quality industrial dust collection systems for use in a wide range of commercial spaces. But how does an industrial dust collection system work?
How Industrial Dust Collection Systems Work
For a start, it is important to note that there are different types of dust collection systems. While one might be as good as another in certain circumstances, each type is best suited to highly specialized processes and in specific situations where a certain dust removal capacity is called for.
Types of Dust Collection
- Sanding Dust Collection
- Grinding Dust Collection
- Buffing Dust Collection
- Abrasives Bead Blast Dust Collection
- Multi-Operation CNC Dust Collection
- Combined Sanding & Grinding
- Battery Plant Dust Collection
- Plasma Fume Collection
- Wood Dust Collection
- Titanium, Magnesium, Zerconium Grinding Dust Collection
- Product Conveyance Dust Collection
- Food Powder Dust Collection
- Vitamin, Food, & Supplement Dust Collection
- Pharmaceutical Dust Collection
- Carbon Fiber Dust Collection
- Plastic Collection
Types of Dust Collection Systems
- Agricultural
- Blasting
- Chemical Processing
- Fiberglass
- Fibrous/Fluffy Dusts
- Food Processing
- Glass
- Laser Cutting
- Machining
- Metalworking
- Metalworking – Forging and Recycling
- Paper Scrap
- Pharmaceutical
- Plasma Cutting
- Powder
- Retrofits
- Rubber Grinding
- Sanding/Grinding/Sawing
- Seed Processing
- Thermal Spray
- Welding – Ambient Fume
- Welding – Source Capture
- Woodworking
Treating Dust Laden Air
The primary components of a dust collection system are a dust filter, a blower, a receptacle, a dust removal system, and a cleaning system. Like any air filtration system, a dust collector works by circulating air that is contaminated with dust and pushing it through or over a filter. Different types of filters and different levels and arrangements of air circulation or suction power are used to achieve this.
Typically, the dust from the treated air will be caught or stopped by the filter as the air comes into contact with it. The dust will then fall into a sediment catcher or it will be mechanically scrubbed, wiped, shaken, or pushed into the sediment collection area.
Dirty air containing dust particles enters the collector through a system of ducts. Then the air comes into contact with a series of angled pieces of metal called baffles which slow the air down to prevent the dust from hitting the filters at a speed that would damage the filters. The air is then moved into the plenum, which is another word for the sediment collector mentioned above.
Capturing Dust
At this point, the air is passed through the cartridge filters. With some systems, these are suspended vertically from a tube sheet, which is the metal sheet that separates the clean and dirty air spaces. The filters are pleated to provide greater surface area for filtration, and some system types use a nanofiber material that is able to filter out especially fine dust particles.
The filters then capture the dust and some of it will fall into the plenum and some will remain stuck to the filters. Gaskets mounted at the apex of each filter for a seal between the filter and a tube sheet which prevents the dust from escaping.
Filter Cleaning
Of course, dust filters must be cleaned from time to time. Some systems use pulses of compressed air to hit the filters. The air moves in the opposite direction from the direction of the incoming air to be filtered, which helps disrupt clinging dust.
Other systems use other means such as shaking. Some need to be removed and can be washed, agitated, or wiped to clean them.
There are a wide variety of dust filter system types. Some are well suited to serving the needs of wood shops. Others work well for paint sanding, and many more are considered ideal for other types of production processes. Where the respiratory health of workers is a concern, personal protective equipment and proper ventilation are important parts of your dust mitigation plan.
To learn more about industrial dust collection systems and obtain a quote on a system designed and optimized for your production space, get in touch with AAir Purification Systems today.
Filter Change Outs
– All filters are sized on an established air-to-cloth/media ratio (cubic feet of air/gas per minute to square feet of filter cloth/media. This is also referred to as filter rate.
– In many cases the end-user will specify a desired air-to-cloth/media ratio, or one will be determined from past experience for testing.
Considerations for establishing the air-to-cloth/media
ratio include:
- Particle size and characteristics
- Application; is it nuisance venting or process collection
- Operating hours
- Inlet grain loading
- Moisture content of the product
- Operating temperature
Common Types Of Dust Collectors
- Shaker Collectors
- Reverse Air Collectors
- High Pressure, Low Volume (Pulse-Jet) Collectors
- Medium Pressure, High Volume Collectors
- Envelope style Shaker units
- Wet Process Collectors
- Electrostatic Precipitators
- Packed Tower Scrubbers
- Spray Tower Scrubbers
- Various Fan Cleaning Collectors
Cyclone Separators
Cyclones are centrifugal devices in which air enters tangentially, causing material to be forced to the outside of the cone and discharged though a hopper. Clean air exits from the top of the cyclone. Cyclones are sometimes installed in front of a dust collector as a pre-cleaner in high grain loading applications.
Pulse-Jet Cleaning
Pulse-Jet cleaning using compressed air at 90-100 PSIG is the most commonly used method for cleaning filters in both Baghouses and Cartridge dust collectors The major components for this cleaning system include a Timer Board, Solenoids, Diaphragm Valves, compressed air manifold and Pulse Pipes located above the filters.
A signal is sent from the timer board to the solenoid valve which is connected to the diaphragm valve by a pneumatic tube. When the solenoid valve opens it energizes the diaphragm valve releasing a burst of low volume high pressure air into the pulse pipes. This creates a shock-wave in the interior of the filter bags or cartridges dislodging the dust from the exterior of the filters
Cartridge Collectors
Excluding extremely high temperature applications, Cartridge Collectors can and are used on most dust collecting applications. Because of their wet laid or melt blown manufacturing process, Cartridge Collector medias are inherently more efficient than needle punched felted baghouse medias. Most Cartridge Collector medias are not as dependent on a heavy dust cake on their surface to achieve good efficiencies as are Baghouses.