The Art of Reverse Tempering

Cooling emergency shower feed water in hot environments is a way to prevent additional injury.

• By Casey Hayes
• Sep 11, 2007

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.

When actuated, the emergency equipment would deliver very hot water to the injury victim—exacerbating the injury, creating more physical harm, or causing the victim to recoil from the flow and cease the drench or irrigation protocol.

With respect to cooling high-ambienttemperature water to bring it within the guidelines, the most popular approach is to size a chiller and recirculation loop to maintain the proper temperature at all times for all equipment on the loop. A variety of different products are available based on the volume of water required at peak demand and the footprint of the recirculation loop specified. The accompanying photo shows a large-capacity separate chiller plumbed directly to an outdoor enclosed emergency environment drench shower booth.

This configuration can also be used to allow the chiller to serve the needs of several showers on a closed recirculation loop. As is also the case with warming technologies, all components must be matched to ensure the availability of proper peak flow rates and temperatures.

Emergency equipment manufacturers are in the best position to assist with system design because they know their equipment flow rates, peak demands, and other associated requirements.

A Step-by-Step Management Process
Just as progress has given us full function emergency equipment and, later on, tepid water requirements and solutions, it has now also given us a clearly defined minimum and maximum range of acceptable outlet water temperatures. Designing and managing an emergency equipment system that is capable of delivering sustained use volumes of properly tempered water should be a step-by-step process.

It’s a matter of identifying your risks, sizing your total system for peak flow use, and factoring in local water conditions (pressure and temperature), as well as seasonal and process-related variations. Only then is it possible to specify and match your overall need to a tailored system, one that is capable of delivering emergency equipment water temperatures within the required range. Even in international areas that are not covered by ANSI’s standard, the common-sense approach used in establishing the Z358.1-2004 language should be used as a guide for properly preparing for the first aid needs of workers in any and all environments.

This article originally appeared in the September 2007 issue of Occupational Health & Safety.