Page 22 - OHS, May 2022

COMBUSTIBLE DUST
Are Vacuum Conveyors Panacea for Safety Hazards?
Automating manual material handling tasks with vacuum conveyors can be the remedy.
VBY DOAN PENDLETON
acuum conveyors won’t solve every safety hazard, but they do eliminate a great number of hazards inherent during manual transfer of powders and bulk solids, such as work-related musculoskeletal disorders (WMSD),
fall, respiratory and dust explosions.
Until fairly recently, safety improvements often fell into the
intangible financial category of cost avoidance—reducing the potential for direct and indirect costs of injury and the resultant increase of insurance rates—relegating them to the bottom of the list of capital expenditures.
That model of thinking has shifted to one that bonds automation to safety. Automation increases safety by eliminating tasks that can cause injury, and Liberty Mutual asserts, “an environment of increased safety due to automation can also boost the bottom line.”1
Manpower and labor costs are eternally hot topics across all industries, and the acute manpower shortage plaguing manufacturing today exacerbates manufacturing’s already shrinking workforce. This acute shortage increases the likelihood of worker injury due to new and untrained workers being more prone to accidents and injury, according to Liberty Mutual, “leading to absences, sick days, and workers compensation claims.2
Automating materials transfer with vacuum conveyors regularly produces savings through reduced manpower, reduced materials costs, increased uptime, improved product quality and a healthier, cleaner environment. Available in a variety of sizes, types and materials of construction, including carbon steel, 304 or 316 stainless, basic vacuum conveying systems consist of a single pick-up point, a vacuum receiver, a vacuum producer, convey tubing and a control panel.
Vacuum conveying systems are fully enclosed, protecting materials from air, dirt and waste. Because product does not escape from vacuum conveying systems, particulates that can endanger workers respiratory health or settle on equipment and surfaces posing an explosion hazard are prevented from entering the environment.
Air-operated venturi powered vacuum producers are by far the safest vacuum source for vacuum conveyors as they are intrinsically safe by design, generating no heat or sparks. Where compressed air is not sufficient, or when conveying materials at higher rates and longer distances, positive displacement pumps are the preferred vacuum source for vacuum conveying.
Suitable for food, pharmaceutical and chemical industries to load mixers, packaging machines, tablet presses, volumetric or gravimetric feeders and any other application where bulk dry powders are conveyed to processes from 300 feet away, vacuum conveying applications and designs are as diverse as industry itself.
Vacuum conveyors can be as simple as pre-engineered up-and- in systems that work on timed intervals or can be sophisticated systems that simultaneously deliver materials from multiple
18 Occupational Health & Safety | MAY 2022
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pickup points with weighing and batching capabilities. There are also mobile conveyors, which can be wheeled to different areas within a facility and used with a variety of process and packaging machines, maximizing utilization and floor space. Mobile and column lift conveyors raise and lower material receivers giving workers the ability to clean and sanitize at floor level, eliminating the need for workers to clean from elevated surfaces in awkward positions.
Two of the most common reasons that facilities invest in vacuum conveying systems is to eliminate safety hazards inherent with manual handling or to meet production demands. Regardless of the primary goal, vacuum conveyors always provide a safer working environment with multifaceted cost benefits, with labor savings topping the list.
Typically, manual loading of process and packaging machines involves two workers to mitigate hazards associated with lifting and loading materials into elevated equipment like mixers, tumble blenders or auger fillers and therefore requires some climbing. Automating material handling eliminates the need for two workers for safety.
When a global OEM of automation equipment for mid-sized and industrial bakeries designed a new 10-foot-wide topping spreader for a bagel customer, its goal was to include a fully enclosed automated loading and reclaim system to eliminate needless labor and open manual handling which poses both worker and food safety hazards.
To fully eliminate laborers needing to climb and work on an elevated surface to monitor even distribution of material across the length of the dispensing machine, the vacuum conveying system included a distribution screw that evenly distributed toppings across the length of the dispensing machine, regulated by a level control.
Beyond eliminating ergonomic, repetitive motion and fall hazards, the bagel producer had significant annual savings in labor and administrative costs since the new system was more set it and forget it, no longer requiring a laborer for duration of the process.
Safety doesn’t always focus on WMSD’s. Quite often, dust is the hazard needing mitigation. Manual dumping of bulk solids and powders creates a lot of dust that can enter into workers’ breathing zones and settle in hard-to-reach places. While vacuum conveying is often used to eliminate these hazards and reduce housekeeping costs associated with fugitive dust, sometimes vacuum conveyors are used as a solution to reclaim materials from dust collectors and prevent buildup within the collector.
In industries where raw materials dominate half of the cost of production, such as the paint and coatings industry, reclaiming and returning materials to the process not only reduces costs, but preserves product quality by ensuring all formulation weights make it into the product.
To amplify the safety of its dust collection system that captures fugitive dusts released during the dispersion process and, to get