Page 18 - Occupational Health & Safety, May 2018

COMBUSTIBLE DUST
which an expert inspects the plant and identifies all of the risks. The inspector will look for issues such as potential for static electricity to create sparks where dusts are suspended in the air. For example, if the workers are using a standard shop vacuum to clean up the dust, it may generate a static charge due to being ungrounded, and that can ignite the powder.
Explosions commonly begin inside a piece of equipment, such as a dust collec- tor or a dryer, or inside process equipment, so a thorough inspection will include the insides of all equipment. There are a num- ber of ways of dealing with that type of risk. One is through an explosion vent, which directs the force through a certain exit in a direction that will not put any workers at risk. Another choice is a fire suppression system inside the equipment. The device sprays dry chemicals into the chamber to suppress the explosion. Lastly, the potential for injury and damage can be minimized by investing in equipment heavy enough to withstand an explosion without falling apart or deforming.
Dust collectors are used to control air- borne dusts. For example, in a facility that grinds corn, a dust collector will be used to remove airborne dust that could otherwise build up and explode. However, in older facilities, those dust collectors are set up inside the building. The process of retro- fitting may require that the dust collection chamber be relocated outside the building, where, if it explodes, it will be less likely to cause damage and injury.
Improper ignition control can lead to sparks that ignite air- borne dusts. Many companies have been fined because they don’t have appropriate electrical equipment for operation in
a dusty environment.
Electrical equipment must comply with national electric code. Improper ignition control can lead to sparks that ignite air- borne dusts. Many companies have been fined because they don’t have appropri- ate electrical equipment for operation in a dusty environment.
Housekeeping, Documentation, and Worker Safety
An often overlooked contributor to dust problems is a simple lack of housekeeping. Many companies assume that a dirty plant is the nature of the business, and allow dusts to accumulate. However, that accu- mulated dust represents a fuel source that can feed a fire in case of an accident. One of the goals of OSHA’s NEP is encourag- ing housekeeping programs to prevent the buildup of dust.
OSHA’s guidelines indicate that cleaning is generally needed whenever a layer of dust reach- es 1/32 inches (the thickness of a paper clip) over a surface area of at least 5 percent of the floor area.
OSHA’s guidelines indicate that clean- ing is generally needed whenever a layer of dust reaches 1/32 inches (the thickness of a paper clip) over a surface area of at least 5 percent of the floor area. That calculation should include dust on beams, joists, ducts, and the tops of equipment. Vertical sur- faces may also count if dust sticks to them.
Housekeeping programs should include procedures for equip- ment failure and other unusual situations that could lead to a buildup of dust.
Some plants already have stringent housekeeping standards, such as factories regulated by the FDA or plants that must conform to bakery industry standards. Those plants tend to be very clean of com- bustible dust. But even those plants can have problems if a machine fails and dust accumulates. Housekeeping programs should include procedures for equipment failure and other unusual situations that could lead to a buildup of dust.
OSHA is also requiring the inclusion of combustible dust hazards in its safety data sheets (SDS). Outdated safety sheets, which used to be called material safety data sheets (MSDS), are no longer acceptable. Workers
Workers should know how to
get out if there’s an accident, and OSHA has fined companies whose workers do not receive all of the required information.
handling combustible dusts should be in- formed that the materials they are handling are potentially combustible.
Safety procedures for workers should include an emergency escape plan. Work- ers should know how to get out if there’s an accident, and OSHA has fined companies whose workers do not receive all of the re- quired information.
Many larger companies are up to date and aware of the stricter regulations, but small companies operating on a shoestring budget could be caught unprepared if inspected.
The expense of retrofitting equipment is justified, compared to the risk to human life and the high dollar cost of a dust explosion. Once equipment is retrofitted, it should be checked out regularly to make sure the dust handling components are in good condi- tion and working properly. Specialized vacuum cleaning and pneumatic conveyer systems can be an important part of a pro- gram for handling combustible dusts.
David Kennedy is Business Development Manager at VAC-U-MAX, a worldwide leader in Bulk Material Handling Systems and Industrial Vacuum Cleaning Systems. The VAC-U-MAX Industrial Vacuum Clean- ing product range includes Portable, Contin- uous, and Central Systems designed for high volume recovery of many materials including powders, liquids, sludge, flammable liquids, and combustible dusts for Class I and Class II environments. His career at VAC-U-MAX spans 23 years, beginning as sales manager for VAC-U-MAX’s Industrial Vacuum Clean- ing Division, where he developed plant safety and OSHA regulation experience, focusing on plant and operator exposure to dusts and combustible dusts. He has an additional 14 years of global sales and systems application experience in conveying and filtration for the chemical, petrochemical, food, pet food, and other general manufacturing industries. To learn more about VAC-U-MAX’s full range of industrial vacuum cleaning systems, visit www.vac-u-max.com.
18 Occupational Health & Safety | MAY 2018
www.ohsonline.com