FAQ: Our dust collection system handles a very fine dust and is having problems with dusting and emissions. What can I do to fix this problem?

The most obvious fix is to upgrade to a filtration media with higher efficiency. There are many good choices available, and a reputable filter supplier should be willing to guarantee in writing that the maximum emissions rate will fall below threshold limits established by OSHA or EPA for the dust in question.

Filtration efficiency is only part of the picture, however. Dust collector cartridges with open-pleated media tend to hold more dust between cleaning pulses and release the dust more readily during cleaning than filters with tightly-packed media. Most dusting and emissions problems occur during pulsing, so this difference in cartridge construction can make an impact. Also, a good electronic control system – programmed to provide “on demand” rather than continuous pulsing – will prevent over-cleaning of cartridges and reduce the chance for dusting to occur. As a side benefit, on-demand cleaning will save on compressed air and energy costs. For more information, read the article, Asking the Right Questions.

Dust Collectors for High Pressure Applications

For some processes, a dust collector with extraordinarily high suction is required. We're talking up to 17 inches Hg (Mercury)!  As you would expect, this type of unit is a heavily reinforced dust capture vessel. It is commonly used as a central vacuum system, positive or negative product receiver or high pressure bin vent in a many industries and processes.

Controlling emissions and filtration efficiencies don't have to be compromised with these types of units. Look for 99.99% (MERV 11) or 99.999% (MERV 15/16) on 0.5 micron particles. Cylindrical vessels with cyclonic tangential inlets knock out most of the dust as it enters, minimizing dust contact with the filters (which prolongs service life). Options can include explosion vents for combustible dust applications, bag-in/bag-out (BIBO) access door and continuous liner discharge for pharmaceutical or hazardous dust.

An installation photo of a high vacuum dust collection can be seen here. Additional, technical information can be found here.

Cartridge Dust Collectors Slash Emissions, Save Water and Energy for Major Mine

Controlling the high levels of dust generated in crushing operations to meet stringent permitting requirements is a difficult challenge for mining engineers. At one U.S. copper mine, the use of a cartridge-style dry dust collection system has reduced emissions to a level of only 0.00037 grains/dry standard cubic foot (dscf) average. This is just a fraction of the required limit of 0.02 grains/dscf – while delivering added benefits of energy savings, water savings and ease of maintenance.

Read the full case study that appeared in Technology News. A PDF file of the article can also be downloaded.

FAQ: What are the ATEX requirements for industrial dust collection?

ATEX is short for the French term ATompheres EXplosibles in the title of the 94/9/EC directive. ATEX is related to dust collection by providing guidelines for equipment and electrical components used in different levels of explosive environments. ATEX provides guidelines for end users or workplaces and equipment manufactures.

• ATEX 95 equipment directive 94/9/EC, Equipment and protective systems intended for use in potentially explosive atmospheres;
• ATEX 137 workplace directive 99/92/EC, Minimum requirements for improving the safety and health protection of workers potentially at risk from explosive atmospheres.

Employers must classify areas where hazardous explosive atmospheres may occur into zones. The classification given to a particular zone, and its size and location, depends on the likelihood of an explosive atmosphere occurring and its persistence if it does.

Areas classified into zones (0, 1, 2 for gas-vapor-mist and 20, 21, 22 for dust) must be protected from effective sources of ignition. Equipment and protective systems intended to be used in zoned areas must meet the requirements of the directive. Zone 0 and 20 require Category 1 marked equipment, zone 1 and 21 required Category 2 marked equipment and zone 2 and 22 required Category 3 marked equipment. Zone 0 and 20 are the zones with the highest risk of an explosive atmosphere being present.

This chart (click thumbnail image) will help relate the equipment category to the equipment area or zone. An instruction manual for an ATEX classified dust collector can be requested/downloaded here.