When it comes to protecting the health and safety of workers, limiting silica emissions is a top priority for manufacturers all over North America. The Occupational Safety and Health Administration (OSHA) set a rule in 2016 to protect manufacturing employees from the hazards of crystalline silica: www.osha.gov/Publications/OSHA3681.pdf.
The rule sets an action level of 25 µg/cu m and a permissible exposure limit (PEL) of 50 µg/cu m for silica averaged over an eight-hour day. Since setting compliance deadlines for different industries in 2017 and 2018, OSHA has issued hefty fines to noncompliant companies, aiming to safeguard workers from respiratory and other health issues caused by silica.
Workers’ safety is a top priority for many manufacturing companies, but the issue of productivity comes in at a close second. Applications that generate silica dust are generally very messy, making it more difficult for workers to access equipment and maneuver around the facility.
Applications in the construction and primary metals industries are the most prone to silica dust, whether it’s gypsum board, glass, or brick, block, and concrete. At its core, this type of manufacturing involves taking a material and transforming it into a value-added product. Dust is created at multiple points all along that process, which usually takes place in enormous facilities.
With health, productivity and the general function of a plant at stake, what should manufacturers do to arm their workers for battle against silica dust? Is a broom and dustpan enough? The short answer is no, but it’s important to understand the different engineering controls manufacturers can use to maximize OSHA compliance and protect workers.
Engineering Controls: The Basics
Engineering controls limit silica emissions at the source. It’s a broad term, encompassing every type of tool, tactic and equipment used to keep silica away from human airways.
The most rudimentary engineering controls for silica are now prohibited by OSHA: dry sweeping, dry brushing, and compressed air seem like simple fixes to many plant managers, but oftentimes they are only successful in pushing the dust from one end of the plant to the other. In other words, they don’t help to eliminate dust at the source.
The layout and ventilation in a manufacturing plant are also considered engineering controls, because they affect how silica dust travels, where it settles and whether it becomes a problem for workers. That’s useful to know in the planning phase of a plant, but for all those looking to make the most of their existing space, a vacuum system is the next best choice.
Advanced Engineering Controls for OSHA Compliance
Thanks to their sturdiness and versatility, vacuums are some of the best engineering controls available. That said, there are a few important distinctions between different types of vacuum systems and their level of effectiveness in combating silica dust.
In these massively messy facilities, commercial-grade vacuums or “shop vacs” won’t cut it. Manufacturers often have higher densities of dust and debris they need to clean in one space, and smaller vacuums typically can’t handle the volume or size of the material.
On the other side of the spectrum, outsourced vacuum trucks are quite large and come in handy when facilities are overwhelmed by large volumes of dust. On the flipside, they are not easily maneuvered between equipment and tight spaces, and the cost of several consecutive rentals can be prohibitive.
Vacuum trucks are considered high-volume, low-vacuum systems, which means they can hold large quantities of material but may struggle with higher densities. To avoid the high capital expenditure of vac trucks and tackle silica dust on the spot, many manufacturers turn to industrial vacuum rentals or purchases.
Industrial vacuums — considered low-volume, high-vacuum systems with smaller capacity and higher suction — typically come in two forms. One is a central vacuum installed in a fixed position in the plant, with several hoses that allow workers to clean spills at specific points in the process where dust is known to accumulate. Another is a portable vacuum, which can be easily moved around the facility by forklift and used to clean messes on the spot.
“When you need to pick up massive amounts of material in a short amount of time, you need a ton of power in a small package,” explained Scott Woodward, US sales manager at DuroVac, a company that makes heavy-duty vacuum systems for manufacturers across all industries. He mentions DuroVac’s silica-specific vacuum, the PowerLift Silica, as an example. “The system can move 6–8 tons of sand in an hour with a 40-hp vacuum. It also comes with a HEPA filter.”
A high-efficiency particulate air (HEPA) filter is another prime example of an engineering control designed for silica control. Thanks to the filter’s small pore size, vacuums equipped with HEPA filters handle crystalline silica with a particle diameter down to 0.3 microns at 99.9 percent efficiency.
Even if a manufacturer chooses a different vacuum or opts for a custom design, the system must be fitted with a HEPA filter to comply with OSHA silica regulations.
Finally, the choice of vacuum comes down to reliability. Plant managers will want to look for reliable suction, a durable build and a low-maintenance unit to get the best value for their money. Filter bags should last years instead of weeks or days, because it means less downtime spent on maintenance and less money spent on replacements.
The Joy of Housekeeping
Silica is an abrasive, aggressive material, and keeping up with maintenance is a challenge in itself. Manual cleaning methods do little to eliminate the risk of silica exposure, and shop vacs are too small and weak to make a real dent in the mess.
Woodward recently worked with a manufacturer of acoustical ceiling tile. Each of its massive facilities generated huge amounts of gypsum dust, and the company needed to upgrade its cleaning measures.
“They just had dust everywhere, and nothing they did could keep it clean,” Woodward explained. “They would bring in vacuum trucks for the worst of it.”
The outsourced vacuum trucks were expensive, however, and difficult to maneuver in tight spaces. The manufacturer soon recognized the need to install a portable vacuum in several of their plants.
“Now I’m told the employees actually look forward to the housekeeping, because it’s so much easier to operate in the plant compared to how it was before,” Woodward said. “They can move the vac to any area and get in for a continuous cleaning rotation.”
Manufacturers should speak with an industrial vacuum expert to understand the best model for their application, material, and facility.
The right vacuum will make a significant difference in the presence of silica dust in any given plant. To keep workers protected, manufacturers should also ensure they provide personal protective equipment (PPE) such as masks, conduct training sessions to ensure workers know how to use their equipment and understand the risks of silica, and keep a regular housekeeping schedule.
Anh-Tai Vuongis president of DuroVac. He helps manufacturers keep their facilities silica-free. For more information, call 905-624-4003 or visit www.durovac.com
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