Utility Menu

Powder/Bulk Solids

The Source for Dry Processing and Bulk Handling Technology

Controlling Dust with Curtain Walls

March 5, 2014

Who needs dust control? The answer may be longer than you think.
    Any company engaged in a process handling or generating particulate matter will benefit from dust control practices. Powdered foodstuff/spice mixing and packaging, ceramic cutting/grinding, powdered chemical processing, and packaging are just a few of the applications for which it is critical.

An Issue of Quality – and Safety
Dust or particulate suspended in air can be a nuisance, as well as a quality issue. Most importantly, however, it is a safety issue.
    As a nuisance, particulate generated from cutting, grinding, mixing, etc., can settle on surfaces significant distances from the operation if containment equipment is not in place. Dust on neighboring equipment, furniture, office equipment, windows and floors, becomes a constant drain on cleaning and maintenance resources. As a contaminate affecting product quality, uncontrolled particulate matter can spoil or degrade batches of differing critical materials, whether in chemical processing or food processing.
    From a safety standpoint, there are many circumstances where high enough concentration of airborne dust sized particulate in a closed space can become explosive or flammable. Often this can occur with seemingly innocuous products – those we wouldn’t normally associate with an explosion hazard. How many grain elevator explosions have we read about over the years? Grain dust becomes too highly concentrated in an air space and a spark ignites and sets off an explosive chain reaction.
    Additionally, airborne dust can be a health hazard to employees. These hazards can range from a skin, eye, or bronchial irritation, to more serious issues for folks with asthma. Most serious can be the potential for particulates to cause lung disease like cancer (extremely thorough dust control is a critical component in asbestos remediation).

Methods of Dust Control
There are a number of methods used to keep particulate from one space from contaminating another. Four of the most common include:

* Local exhaust – a high-velocity airflow stream captures particles at the point they are generated and carries them away.
* Exhaust with filtration – a high-velocity airflow stream captures particles and recirculates them through a filter medium, where they are removed.
* Area exhaust – a high-volume exhaust fan draws air from the full room volume to an outside vent or recirculates through a filtration/separation device.
* Barrier separation – simply a wall or partition between affected areas

How Can a Curtain Wall Help With Dust Control?
Each of the separation methods outlined above relies on moving a volume of air containing the dust particles. This would be accomplished through the use of exhaust fans through ducts. A local exhaust set up would incorporate some type of hood designed to collect the air and particulate being moved and funnel it into the exhaust ductwork. Area exhaust would include multiple draw points through louvered openings in the ceiling or wall. Either of these methods could and most likely would include some type of filtration or particle separator in line, to remove particulate from the air stream. This is necessary prior to either recirculation of the air back into the space, or discharge of the air into the atmosphere.
    Curtain walls can significantly improve the effectiveness of these systems, as well as offer the opportunity for cost savings, both in the initial cost of the equipment and in direct operating cost.
    Anytime a space is to be exhausted, the smaller the space can be made, the smaller the exhaust equipment can be as specified. Partitioning around a dust source with a curtain wall takes full advantage of this relationship. By reducing the volume of the space to be exhausted, smaller fans can be used, with less total air movement being required. Lower air velocity through filter media increases the effective particle separation of the device. Additionally, lower air flow through the filter reduces the frequency required for change out or cleaning.
    In some cases, an application will include a temperature differential as well between a dust controlled space and the area surrounding it. Curtain walls are available with several levels of insulation, as needed. These walls can be instrumental in maintaining product integrity and ensuring employee comfort around the space.

Curtain Walls Are a Flexible Solution
In addition to reducing the volume of space to be exhausted, curtain walls act as an effective physical barrier on their own, blocking transfer of dust particles from space to space. Curtain walls can be single layer fabric, or multi-layer insulated. They can easily be fitted with clear vision panels for visual communication between spaces.
    They are flexible by nature, yet very durable, and can withstand contact from machinery or product, and simply “bend without breaking,” in contrast to a hard permanent wall. They are also relatively easy to re-configure, if a space needs to be enlarged or reduced, or the shape of the space footprint needs to change. No “de-construction” is required. Curtain walls are easily installed, can be simply trimmed around conduit, piping, ductwork, etc., and can be anchored to the floor to withstand pressure differential across them.
    Depending on the application, a curtain wall can be suspended from the room ceiling, or they can be supplied with a stand-alone framework from which to hang. They are available as stationary and sliding (suspended from roller track), and can be fitted with strip curtains, personnel doors, or high-speed industrial doors for full range of access to the space.
    Chuck Ashelin is engineering manager with Zoneworks (Milwaukee, WI). For more information, visit www.zoneworks.com.

For related equipment reviews, articles, and news, visit our Dust Collection & Air Pollution Control Equipment Zone

Click here for information about the International Powder & Bulk Solids Conference & Exhibition