Since we manufacture dust control systems that use filters (bags or cartridges) to collect and control dust, we obviously have a preference for dry systems. But what about a wet dust collector? Both wet and dry systems have their advantages and disadvantages. Many of them depend on your process, the type of dust you produce, and your individual needs. Baghouse and cartridge filter dust collectors have worked safely and efficiently for many years and in many different applications. However, as concern and awareness of combustible dust issues grows, some companies are considering a wet system that “scrubs” the air stream with water for dust control. Read on for some points to think about:
THINGS TO CONSIDER:
- Type of dust
Wet dust collector systems are often used where there is a concern about combustible dust, especially metal dust, combined with a high likelihood of sparks coming into contact with the dust. Dry systems can also be used in this application. Although, if there is a risk of deflagration, the system should include safety devices such as spark traps, and fire-retardant filters that will not fuel a fire. Our DeltaMAXXTM nanofiber fire-retardant filters are rated to safely control a deflagration inside the collector. Wet systems decrease the risk of fire or explosion because the air travelling through the collector is cleaned by “scrubbing” it with water before allowing the dust to settle out. This ensures that even if there is an ignition source, there’s no dust cloud or dry dust to ignite. On the other hand, dry collectors with proper maintenance and housekeeping have been used safely for many years with almost every type of dust imaginable.
- Particulate Size
The filters in dry systems are more efficient at collecting and removing very fine particulate, with nanofiber filters 99.9% efficient in capturing particulate down to .3 microns. While some cutting and grinding may produce larger particulate, applications like welding, plasma and laser cutting, and other processes produce very fine particulate metal fumes that are more efficiently captured by a dry collector system. In a wet system, it may be difficult to get very small particulate to settle out of the water so it can be collected, although some wet systems are designed to handle this. Overall, a dry collector is more efficient for smaller particulate, smoke, and welding fumes.
- System Setup
A wet dust collector is often used on individual work stations such as downdraft tables. When a central dust collection system is used, the requirements for ductwork and proper CFM throughout the system may be similar for wet and dry types. Because a dry system is more efficient at capturing smaller particles and fumes, these types of systems are often used where there are multiple locations in a facility producing welding or cutting fumes. Since dry systems are more effective in collecting smoke and fumes, they may be able to operate at a lower CFM, which saves energy and decreases the noise produced by the system. A wet collector is often used on equipment like a downdraft table where sparks and metal dust are in close proximity, although many downdraft tables use a dry collector because they produce small particulate, smoke, or fumes. A full assessment of your company’s needs will help determine which type of system would be most beneficial for you both for safety purposes and in long-term operating and maintenance costs.
- Maintenance and Disposal
Depending on your type of dust, there may be regulations for how your material needs to be disposed of. With a dry system, bags or cartridge filters usually filter the dust into a container for disposal. With a wet system, the accumulated dust settles out of the water and the sludge must be collected and disposed of. Since the sludge will eventually dry, it is often mixed with an inert substance like sand to make it safer to handle. Many waste management facilities have different regulations for dry and wet materials.
To make a wet collector efficient at removing smaller particles, the system requires higher water pressure and a lot of energy, which increases the cost. For larger particles, the energy costs are lower because it is easier to get these particles to drop out the air stream. A dry collector requires compressed air to periodically clean the filters, and the frequency of pulsing can be adjusted to suit individual needs, and can be decreased by the use of filter media like DeltaMAXX nanofiber that pulse-clean more efficiently. Both types of systems require appropriate equipment to maintain the correct air flow.
Maintaining a dry dust control system usually means changing the filters regularly and monitoring differential pressure. The filters will contain dust and must to be disposed of according to the standards for that material, and the collected dust must also be disposed. Maintaining a wet dust collector system includes making sure the water remains clean, without too much material dissolved in it, and disposing of contaminated wastewater. Removal and disposal of sludge is required for a wet collector, and the sludge may need to be mixed with other materials or dried to make it safer or more easily disposable. Both types of systems will require proper housekeeping and maintenance of the ductwork and work areas to make sure dust doesn’t accumulate.
Contact the professional staff at Imperial Systems today to learn more about solutions to your dust control concerns. 800-918-3013.