Providing emergency eye wash and shower facilities for employees who work outdoors and are exposed to chemical hazards can be challenging during the winter months. Standard equipment will freeze when the mercury dips below 32F, rendering the station useless and creating an unsafe work environment.
According to the ANSI Z358.1-2004 Standard for Emergency Eye Wash and Shower Equipment, emergency wash systems must either be shielded from freezing or outfitted with freeze-protected equipment when the possibility of freezing exists.
Manufacturers of emergency eye wash and shower equipment have developed freeze-resistant and freeze-protected equipment to meet cold-weather needs. Both systems work well for their designed application. There are differences between the two styles, however, that dictate where each should be used.
Designed to withstand subfreezing conditions for brief periods, freeze-resistant systems remove any portion of the system containing water from direct exposure to the elements. Valves and piping that contain water are either located in a heated building or underground below the frost line. The eye wash heads, shower head and additional piping are placed outside, exposed to water only when the system is activated.
Special freeze-prevention valves may also be incorporated into the design. When these valves sense temperatures approaching 40F, they partially activate flow. They fully activate around 35F to move water in the system and prevent freezing.
When freeze-resistant systems are shut down after being activated, water will remain in the system where it can freeze and eventually cause damage. Freeze-prevention valves require a continuous water flow to prevent freezing. This wastes water and can be a slip hazard depending on the drain system in place. Because of these conditions, freeze-resistant systems are recommended for areas where subfreezing temperatures will be present for short periods only.
Freeze-protected systems are ideal for locations where temperatures are expected to drop below freezing for extended periods of time. These systems are electrically heat-traced and insulated for extreme cold weather. Manufacturers generally design systems to withstand temperatures well below 0F.
Heat-tracing cables and added insulation make freeze-protected equipment more expensive and a bit more complicated to install than freeze-resistant systems. For a majority of applications, freeze-protected systems are the only option.
Keep in mind that neither freeze-resistant nor freeze-protected systems, in their base design, are water-tempering systems. Water dispensed from both types will be the same temperature as the supply source.
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