Efficient Plant July/August 2020 - 16

feature | conveyor systems
Life-cycle vs. low-bid design gains, losses

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Low bid

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Savings

Lif
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Losses

The return on better
design and quality is
realized over the
extended life and
safety of a system.

Return on safety

Costs over time
methods of protecting workers can vary greatly. In many
cases, it will be necessary to use more than one control
method, by incorporating lower-ranked controls. However, these lower-ranking approaches are best considered as
support measures, rather than solutions:
 PPE can be effective, but the devices can be worn
improperly, may be uncomfortable to use, can be difficult to monitor, and offer a false sense of security.
 Administrative controls (changes to the way people
work) create policy that articulates a commitment to
safety but can be easily shelved and forgotten.
 Warning signage is generally required by law, so this
is less of a method than a compliance issue.
 Engineering controls that allow remote monitoring
and control of equipment or involve gates and inspection
doors to obstruct access, greatly reduce exposure, but
again, do not remove the hazard.
 The Substitute method replaces something that
produces a hazard with a piece of equipment or change
in material that eliminates the hazard. For example,
manual clearing of a clogged hopper could be replaced
by installing remotely triggered air cannons. However,
operators may find that this method is not a practical
solution for all belt-conveyor systems.
 Eliminate by design usually involves longer, taller,
and tightly sealed loading chutes to control dust and
spillage or heavy-duty primary and secondary cleaners

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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
the space, budget, and application.

PREVENTION THROUGH DESIGN
Another way of saying "eliminate by design" is prevention through design (PtD), an initiative spearheaded by
The National Institute of Occupational Safety and Health
(NIOSH, Cincinnati, cdc.gov/niosh). The institute report
points out that, while the underlying causes vary, studies
of workplace accidents implicate "system design" in 37%
of job-related fatalities.
Although injuries are the focus of the NIOSH report,
the prevention aspect of design also greatly affects production. In most cases, workplace hazards produce consequences such as downtime, product loss, and reduced
efficiency from spillage, dust, and early equipment failure.
Cost is most often the main inhibitor to PtD, which is
why it's best to implement safer designs in the planning
and initial construction stages. The added engineering
cost of PtD is often less than 10% but has enormous benefits in improved safety and increased productivity.

LOW-BID VS. LIFE-CYCLE COST
Although the policy is generally not explicitly stated by
companies, the low-bid process is usually baked into a

JUL/AUG 2020

7/15/20 2:26 PM

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Efficient Plant July/August 2020

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