Safely operating dust collection systems has
become increasingly complicated over the last decade. New regulations from OSHA
and the NFPA have sought to improve the safety of collecting combustible and
explosive dusts. A dust collection system helps keep your shop clean and will
protect your health. Smaller dust collection systems use a single-stage vacuum
to perform suction and filtration the dust is drawn into an impeller and
collected in a container. Air is recirculated into the shop after passing through
a filter to trap smaller particulate. Larger systems utilize a two-stage system
separating large particles from fine dust, then drawing the air through the
impeller. The air is then exhausted outsides or to a filtering system and
recirculated back indoors.
Designing and operating a safe and effective
dust collection system begins with a complete and comprehensive analysis of
your dust that identifies the general characteristics as well as the associated
hazards. Establishing basic information such as the bulk density (specific
gravity), terminal velocity, particle size distribution, and moisture content
will allow the collection system to be properly sized. Part of this analysis
should also include determining whether the dust is combustible or explosive in
accordance with current NFPA standards. This is one of the most commonly
overlooked steps because of the associated up-front cost. However, avoiding
this step or using incorrect information can have dangerous consequences. Also,
it’s important to take the time to review the MSDS sheets (if available) for
other potential hazards and guidance on how to handle the collected material.
A fully operational dust collection system is
comprised of the hood or capture device, the ducting system, the dust collector
and the air moving device. If any one of these components is not designed with
the dust characteristics and hazards in mind, the entire system safety is in
jeopardy. Manufacturers often believe that simply having a dust collector
equipped with an explosion vent is adequate protection but they ignore the
important considerations of the complete system. For example, poorly designed
ducting that does not maintain proper conveyance velocity during operation
creates performance and safety hazards where dust build-up can result in fire
hazards or even structural failure.
Systems must also be properly maintained in
order to achieve the desired level of consistent performance and safety. Filter
changes, removing dust build-up on hoods, pressure gauge accuracy, airflow
validation and non-obstructed explosion vents are just a few of the items which
should be regularly checked to help ensure ongoing safe operation. In addition,
operational and maintenance staff should be sufficiently trained and have a
solid understanding regarding what the target system performance is, how to
verify this performance and how to service the equipment when necessary.
Investments in dust collection systems are
intended to provide protection to your company’s most valuable assets - your
workers and your facility. Dealing with combustible and explosive dust hazards
come with associated additional costs but the risks of not adequately
addressing the issue are much greater. The amount of publically available
information available combined with the documented examples of property damage
and loss of life from dust explosions should compel manufacturers to take the
necessary steps to ensure that their dust collection systems are safe. And,
dust collector manufacturers are willing and eager to help with the education
process so be sure to tap into their expertise and knowledge regarding dust
collection system safety when you are considering vendors to meet your specific
dust collection needs.
