Page 30 - OHS, October 2024

T R A I N I N G : M A T E R I A L S H A N D L I N G
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
pliance are primary challenges identifi ed by those tasked
Lack of training time, budget constraints and employee com-
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, ergo-
nomic, fall and combustible dust hazards.
Manual transfer of bulk powders and solids is inherently dan-
gerous. Anytime powders or bulk dry materials are open dumped
into any process, whether it be into a blender, a hopper or packag-
ing machine, a puff of dust is created, launching particulates into
the air, creating fugitive dust.
Vacuum conveying systems are inherently safe systems that re-
quire minimal human interaction. Fully enclosed vacuum convey-
ing systems use a series of tubes suspended above the production
fl oor to move materials between production equipment like blend-
ers, hoppers or packaging machines. Th e small footprint of these
systems eliminates the complexity that alternative mechanical con-
veying 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 elimi-
nate 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 eff orts 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 fl uctuating worker performance.
Eliminating ergonomic injury is oft en the primary motivation
for automating powder and bulk solids handling. Manual transfer of
materials oft en 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, mini-
mizing economic pressures caused by manufacturing labor shortages.
Vacuum conveying systems deliver a multitude of benefi ts si-
multaneously, such as preserving expensive materials, improving
effi ciency, reduction of housekeeping tasks, easy clean up, simple
design that requires little to no maintenance and the very appreci-
ated benefi t of eliminating the need for workers to wear respirators.
Respiratory protection programs are expensive endeavors
requiring strict adherence to OSHA regulations. Th e 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 diffi culties in maintaining solid
respiratory protection programs.
Engineering out respirable dust hazards with a closed process-
ing 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 mate-
rials handling with automated vacuum conveying systems is for
fall prevention. Most oft en, 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 fi nd a way to load six 160-pound barrels
into a blender six or seven feet off the ground. Aft er years of manu-
ally loading small 160-pound batches into a 55-gallon rotary drum
mixer, the manufacturer knew that an automated system was nec-
essary to prevent ergonomic injury and falls.
Aft er researching automated systems of material delivery to
blenders, the coating manufacturer chose a pre-engineered direct-
charge blender loader designed specifi cally 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 fi nished product from the blender into boxes all while
staying within a specifi c budget. Th e 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, con-
veyors are confi gured specifi c to each application, providing the
power source, fi lters, 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 em-
ployed, 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 so-
phisticated pneumatic conveying system would be far less than
that of a dust explosion that took life and limb and caused long-
term downtime.
Doan Pendleton is vice president of sales and marketing at VAC-U-
MAX. He is an expert in vacuum technology with more than 20 years
of experience designing and engineering vacuum conveying systems
and industrial vacuum cleaners, including combustible dust vacuums
that are redundantly grounded and ideal for combustible dust.
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