The Art of Reverse Tempering
Cooling emergency shower feed water in hot environments is a way to prevent additional injury.
GLOBAL economic growth—spurred
by the popularity of outsourcing
manufactured goods—continues its
unprecedented rise. During this period,
it’s interesting to note that much of the
offshore industrial windfall is focused
within warmer, often downright hot, climates.
Geographically warm areas in
Asia—China, for example—are struggling
to keep pace with a mushrooming
demand for lower-cost parts, components,
and finished products.
Likewise, new manufacturing processes
and advanced technologies often generate
significantly more process heat as they
operate. And if that’s not enough, the
growth in global dependence on Mideast
petroleum resources continues to stress
that industry’s facilities, which are obviously
in very warm climates. So a rapidly
growing number of offshore industrial and
commercial environments are dangerously
hot, due to either natural or man-made circumstances,
or both.
This places an ever-increasing population
of workers in a dangerous position:
Emergency response assets, including
drench showers and eyewashes, must not
only be made available, but these facilities
also require cooling of the water that flows
through them to avoid inflicting potentially
worse injuries on users.
Lest any reader think that this isn’t a
significant situation, consider your Saturday
car wash: When washing your car on
a hot summer day, the water can get mighty
hot if you let it stand in the hose for even a
short time. That’s because water is an ideal
transfer mechanism for heat. The sun heats
the outside of the hose and the water contained
in the hose absorbs that heat very
readily. You then turn on the hose to rinse
the car and get a surprise!
Now, consider the circumstance if
emergency shower feed water is left
standing in exposed piping, where either
high process temperatures or the sun can
significantly raise the temperature. If an
injured worker jumps under the shower or
forces his face into an eyewash stream
heated by the environment it is exposed to,
some dire results could easily follow.
Second and even third-degree burns are
easily possible. In fact, water at 100
degrees F is already sufficiently hot to
damage the delicate tissue of the eyes and
other areas of the body.
For many years, the operating water
temperature range of industrial emergency
drench showers and eyewashes was left
open to fluctuations, based on ambient
temperatures and other exposures. The
water that flowed through emergency
equipment was subject to climatic, source
affected, and other variables that could
raise it to dangerously high temperatures
or lower it to hypothermia-inducing cold
temperatures with no regulations or range
limitations. You pulled the handle, pushed
the flag, or rotated the foot treadle on your
emergency shower or eyewash, and you got
what you got. All of that changed with the
2004 revision of ANSI Z358.1.
Currently, OSHA in 29 CFR 1910.151
requires the availability of suitable first aid
treatment facilities. Direction is given
indicating that “suitable facilities for quick
drenching or flushing of the eyes and
body shall be provided. . . .” In the past,
the definition of “suitable” was generally
left to the specifier’s discretion. However,
ANSI Z358.1-2004 provides clarification,
and that clarification virtually eliminates
all ambiguity.
Sustained outlet temperatures, per the
standard, must be no lower than 60 degrees
F and below 100 degrees F during a full, 15-
minute use cycle for either an emergency
shower or an eyewash. Water that is colder
could lead to hypothermia, while hotter
temperatures can damage sensitive areas of
the body. Additionally, water at a higher
temperature that is applied to chemical splashes actually can intensify the injury.
In either case, the discomfort of the
victim can also lead to premature cessation
of the emergency equipment use.
The idea of an injured worker short-cutting
the required emergency equipment
use cycle because the water is too cold or
hot obviously led to the establishment of
the outlet water temperature range specified
by ANSI.
High Demand from Warm-Climate Plants
Recently, we have seen a dramatic increase
in the number of requests we receive for
Engineered Solutions dealing with cooling
emergency equipment feed water. In these
instances, radiant and ambient temperatures
in many areas within a warm-climate
plant often drive standing water temperatures
up above 120 degrees F. The
dynamics of heat transfer will raise the
standing water temperature at the emergency
equipment to dangerous levels
approaching the maximum ambient/
radiant air temperature.
This article originally appeared in the September 2007 issue of Occupational Health & Safety.