Minimizing Retraining, Error and Injury with Powder Conveying

Vacuum conveyors for bulk powder and solids transfer reduces the need for repeated enforcement and training for respiratory, ergonomic, fall and combustible dust safety.

• By Doan Pendleton
• Oct 15, 2024

Lack of training time, budget constraints and employee compliance are primary challenges identified by those tasked with facility safety. Manual materials handling is the leading cause of work-related injuries, primarily musculoskeletal disorders. When manual materials handling involves powders and bulk solids, the scope of hazards increases, requiring a greater level of safety training and management to mitigate respiratory, ergonomic, fall and combustible dust hazards.

Manual transfer of bulk powders and solids is inherently dangerous. Anytime powders or bulk dry materials are open dumped into any process, whether it be into a blender, a hopper or packaging machine, a puff of dust is created, launching particulates into the air, creating fugitive dust.

Vacuum conveying systems are inherently safe systems that require minimal human interaction. Fully enclosed vacuum conveying systems use a series of tubes suspended above the production floor to move materials between production equipment like blenders, hoppers or packaging machines. The small footprint of these systems eliminates the complexity that alternative mechanical conveying methods pose when navigating around existing equipment. 

One advantage to conveying under vacuum is that should a leak occur, it is always inwards. Vacuum conveying systems eliminate environmental exposures and fugitive dust. 

A Safety Multiplier

When equipment is employed to eliminate, substitute or engineer out safety hazards, time spent on repeated enforcement efforts and retraining diminishes, preserving man-hours for production.

With the estimated direct cost of a single ergonomic injury from exertion at $36,000, the most simplistic vacuum conveying system becomes an economical solution to combat challenges stemming from limited training time and fluctuating worker performance. 

Eliminating ergonomic injury is often the primary motivation for automating powder and bulk solids handling. Manual transfer of materials often requires two operators working in tandem to reduce ergonomic risk when loading materials into process vessels. Vacuum conveyor operation, however, requires a single or no operator, minimizing economic pressures caused by manufacturing labor shortages.

Vacuum conveying systems deliver a multitude of benefits simultaneously, such as preserving expensive materials, improving efficiency, reduction of housekeeping tasks, easy clean up, simple design that requires little to no maintenance and the very appreciated benefit of eliminating the need for workers to wear respirators. 

Respiratory protection programs are expensive endeavors requiring strict adherence to OSHA regulations. The fact that respiratory protection has remained on OSHA’s Top Ten Most Frequently Cited Standards for more than 20 years, reveals that manufacturers and processors face difficulties in maintaining solid respiratory protection programs.

Engineering out respirable dust hazards with a closed processing system is especially important when dealing with metal powders that are toxic to the human body. Additive manufacturing (AM) is gaining attention in the occupational health and safety world due to its combustible, respirable and skin contact hazards (and the usual musculoskeletal injuries associated with heavy materials).

Another objective that leads facilities to replace manual materials handling with automated vacuum conveying systems is for fall prevention. Most often, production equipment is located above workers’ reach, requiring material loading from a mezzanine level where stairs must be climbed with or without materials in hand. Even with fall prevention training and compliant elevated surface safety protocols in place, climbing is a risk that most managers want to avoid whenever possible. 

When steady growth at a thermal spray coating manufacturer necessitated moving to a large-scale mixer to stay ahead of orders, the company needed to find a way to load six 160-pound barrels into a blender six or seven feet off the ground. After years of manually loading small 160-pound batches into a 55-gallon rotary drum mixer, the manufacturer knew that an automated system was necessary to prevent ergonomic injury and falls.

After researching automated systems of material delivery to blenders, the coating manufacturer chose a pre-engineered direct-charge blender loader designed specifically for the direct charge loading of blenders, mixers, reactors and any vessel capable of withstanding a vacuum. In addition to loading the blender, the spray coating manufacturer also wanted a conveying system to transfer the finished product from the blender into boxes all while staying within a specific budget. The coatings producer didn’t want to purchase two conveyors, especially since neither would be in constant use. 

With a facility’s blender or mixer as the primary receiver, conveyors are configured specific to each application, providing the power source, filters, controls and adapters. To meet the coatings producer’s production, safety and budget goals, the direct charge blender loading was built to both load and unload the blender. 

And of course, any time a pneumatic conveying system is employed, costs associated with housekeeping shrink, as well as the potential for a dust explosion because fugitive dust doesn’t escape and accumulate on surfaces. Certainly, the purchase price of a sophisticated pneumatic conveying system would be far less than that of a dust explosion that took life and limb and caused long-term downtime.

This article originally appeared in the October 2024 issue of Occupational Health & Safety.