Chemical Engineering March 2017 - 53

FIGURE 2. Among the various styles for safety
eyewear are the plano (top), which provides basic
impact protection, and safety goggles (bottom),
which seal tightly to the face for protection against
hazardous chemicals
as water, sand, glass, sheet metal
or concrete, look for lenses that are
mirrored, polarized or darkly tinted
and are marked with an " L " for effective
glare reduction.
To support visual function in indoor
applications with specialized lighting,
unique dyes are incorporated into
the polycarbonate lens material that
absorb select wavelengths of radiant
energy (light). Such lenses can
manipulate light to reduce a spectral
hazard or to provide distinctive
filtration for specific viewing tasks.
For instance, in operations where a
high level of yellow light is present,
specialized blue lenses counteract
color distortion and help prevent eye
fatigue. Vermilion (scarlet) lenses are
useful in certain inspection operations
where the color shift enhances
contrast or highlights shadowing
for better inspection results and increased
productivity. While orange
lenses effectively filter blue and violet
light present with UV curing lamps,
amber lenses are commonly used to
aggregate reflected light for a brighter
view in low-light environments. Deep
cobalt lenses are valued by furnace
workers for their ability to deliver excellent
spectral performance while
protecting from harmful IR rays.
Remember, many colored lenses
affect the wearer's ability to identify
colors correctly; selecting lenses with
true color recognition is essential for
traffic signal identification and other
applications that rely on color coding.
Lens coatings
Lens coatings deliver anti-fog properties,
anti-scratch properties, or a
combination of the two. Together,
such coatings prolong a clear, unobstructed
view of the environment,
improving worker safety. Furthermore,
effective anti-fog and antiscratch
coatings extend lens life,
adding longevity and value to your
eyewear investment.
Anti-fogging. Lens fogging is a
leading problem faced by workers
wearing any type of safety eyewear
- and it affects safety, productivity
and compliance. Factors that cause
fogging include the temperature variance
between a worker's body heat
and cooler outside air temperatures;
the change in temperature when
workers transition from warm indoor
environments to cold outdoor surroundings;
and perspiration caused
by exertion. Given its direct associaCHEMICAL
ENGINEERING WWW.CHEMENGONLINE.COM
MARCH 2017
tion with both the worker and the environment,
fogging is nearly impossible
to avoid. How to prevent fogging
is discussed in more detail in part 2,
pp. 56-59.
Scratch resistance. A lens's ability
to resist scratches is of utmost
importance - especially in highhazard
environments like hot, dry,
windy outdoor conditions where flying
dust, sand, debris and fragments
are most likely to make contact with
lenses and cause scratching. Once
scratched, lenses no longer afford
the wearer a clear, uninterrupted or
comfortable view of the workplace
and hazards, and they should be replaced.
To combat scratching, scuffing
and degradation from a variety of
chemicals - and to prolong safety
lens life overall - look for eyewear
with a proven, long-lasting, scratchresistant
hard coat.
Ensure proper fit and comfort
Easily overlooked, the comfortable
fit of safety eyewear directly supports
protection and compliance.
When eyewear fits poorly, it slides or
slips off the wearer or causes painful
pressure points on the temples or
nose bridge. If eye protection isn't in
53
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Chemical Engineering March 2017

Table of Contents for the Digital Edition of Chemical Engineering March 2017
