Controlling conveyor system safety, efficiency

By |  December 21, 2021

All new conveyor systems will inevitably succumb to the punishing bulk handling environment and begin the slow process of degradation.

Systems will eventually require more time and labor for maintenance, leading to shorter spans between outages, longer periods of downtime and an ever-increasing cost of operation.

This is all accompanied by an increased chance of injury or fatality because workers are progressively exposed to equipment in order to perform cleaning, maintenance and fabricate short-term fixes to long-term problems. Total system replacements are cost prohibitive, but to remain compliant and meet ever-increasing production demands, upgrades and repairs are unavoidable.

When examining system safety, improving efficiencies and reducing risks can be achieved by utilizing control methods to alleviate hazards. The consensus among safety professionals is that the most effective way to mitigate risks is to design hazards out of components or systems. This usually requires a greater initial capital investment than short-term fixes, but yields more cost-effective and durable results.

Hierarchy of control methods

Photo: P&Q Staff

Studies show that conveying-related accidents tend to happen where cleaning and maintenance activities frequently take place. Photo: P&Q Staff

Examining the Occupational Safety & Health Administration accident database reveals the dangers of working around conveyors.

Studies revealed that the highest prevalence of accidents are near locations where cleaning and maintenance activities most frequently take place: take-up pulley, tail pulley and head pulley. Designs should be forward-thinking, exceed compliance standards and enhance an operator’s ability to incorporate future upgrades easily and cost-effectively by taking a modular approach.

Designing hazards out of systems means minimizing risk with the intent to bolster safety on them. The methods of protecting workers can vary greatly and, in many cases, it will be necessary to use more than one control method by incorporating lower-ranking controls. Lower-ranking approaches are best considered as support measures rather than solutions in and of themselves, though.

Personal protective equipment, including respirators, safety goggles, blast shields, hard hats, hearing protectors, gloves, face shields and footwear, provide barriers between the wearer and the hazard. The downside is that they can be worn improperly, may be uncomfortable to use through an entire shift, can be difficult to monitor and offer a false sense of security. The bottom line, however, is that they do not address the source of the problem.

Administrative controls create policies that articulate a commitment to safety, but written guidelines can easily be shelved and forgotten. These controls can be taken a step further by establishing active procedures to minimize the risks.

For example, supervisors can schedule shifts that limit exposure and require more training for personnel. Still, these positive steps do not remove the exposure and causes of hazards.

Warning signage is generally required by law, so this is less of a method than a compliance issue. It should be posted in plain sight, clearly understood and washed when dirty or replaced when faded. Like most lower-tier methods, signs do not remove the hazard and are easily ignored.

Installing systems such as engineering controls that allow remote monitoring and control of equipment – or guards such as gates and inspection doors that obstruct access – greatly reduce exposure. Again, though, these do not remove hazards.

Using the substitute method replaces something that produces a hazard with a piece of equipment or a change in material that eliminates the hazard. For example, manual clearing of a clogged hopper could be replaced by installing remotely triggered air cannons.

Examples of eliminating by design are longer, taller and more tightly sealed loading chutes to control dust and spillage, or heavy-duty primary and secondary cleaners to minimize carryback. By using hazard identification and risk-assessment methods early in the design process, engineers can create the safest, most efficient system for their space, budget and application.

Prevention through design costs

Another way of saying “eliminate by design” is prevention through design, a term used by the National Institute of Occupational Safety & Health (NIOSH).

As a department of the U.S. Centers for Disease Control & Prevention (CDC), NIOSH spearheaded the prevention-through-design initiative. In its report, NIOSH points out that, while the underlying causes vary, studies of workplace accidents implicate “system design” in 37 percent of job-related fatalities.

Cost is most often the main inhibitor to prevention through design, which is why it’s best to implement safer designs in the planning and initial construction stages rather than retrofitting systems later. The added engineering cost of prevention through design is often less than an additional 10 percent of engineering, but it presents enormous benefits in improved safety and increased productivity.

The cost of prevention through design initiatives after initial construction can be three to five times as much as when the improvement is incorporated in the design stage. The biggest cause of expensive retroactive improvements is cutting corners initially by seeking lowest-bid contracts.

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