Water Supply Requirements for Safety Showers & Eyewash Stations

Download Application Profile #4 - Water Supplies for Safety Showers and Eyewash Stations

To prevent workplace injuries safety showers and eyewash stations are critical in facilities where personnel can be exposed to hazardous materials and chemicals. Facilities equipped with these stations must be aware of the regulatory requirements and compliance standards to install, operate, and maintain these units. Important factors to address are water supply quality, OSHA and ANSI safety requirements, and the delivery of safe and comfortable water temperatures to employees if a shower/eyewash is activated.

  1. Water Quality: As a general rule of thumb, if it is safe enough to drink, it is safe enough to shower with. An area of concern is ensuring that the water supply is free of any sediment buildup and any bacteria that might have developed in the standing water supply. ANSI standards recommend that all emergency shower/eyewash devices be checked on a weekly basis to ensure proper working conditions, confirm adequate water supply, and flush any sediment/bacteria out of the system. Many shower manufacturers offer units with pipeline strainers or recommend they be installed on a dedicated water supply line.

  2. Water Capacity: Plumbed emergency shower/eyewash equipment requires a line size that will provide adequate flow. The chart below shows typical water pressure and supply requirements as specified by ANSI.


    ANSI Z358.1 is the American National Standards Institute’s standard for Emergency Eyewash and Shower Equipment. ANSI Z358.1-2014 gives the following performance and installation requirements:Drench_Shower.pngmceclip2.png

  3. Delivered Water Temperature: Tepid. In most cases the high temperature condition is of critical concern and a high inspection area for OSHA; however, low temperature hazards are also growing concerns.
      1. Over-temperature/Scald Protection: Supply lines or shower units installed outside are subject to solar heating with internal water temperatures reaching 150°F (66°C) and above. Likewise, indoor units and lines may be subject to high ambient temperature conditions from process, steam or condensate lines. This over-temperature water must be purged from the system to prevent scalding.

        Relationship of Time and Temperature: Studies1 have demonstrated that there are two critical factors that determine the risk of a burn injury occurring: the temperature of the material and the length of time the skin is exposed to the temperature. For water, the following chart provides time/temperature relationships required to cause a full-thickness (3rd degree) burn.mceclip5.png

        Normal safety standards dictate a minimum of 15 minutes wash down in the shower!

        A common device used for over-temperature/scald protection by shower manufacturers and retrofitted by users is a self-contained temperature-activated valve, such as the ThermOmegaTech® HAT/SP or IC/SP designs.

        The internal sensor/actuator operates over a 10°F (5.5°C) temperature differential, with the valve being fully closed at 95°F (35°C) and increasing to full flow if the temperature reaches 105°F (40°C) or above. This purges the hot water from the system, to be replaced by the cooler water in the supply line.

        Valves are normally installed in the station (see typical piping layout) to ensure:

        1. Full station and system piping are purged of hot water.
        2. Valve discharge will not reduce available flow to the shower or eyewash unit.
      2. Low-Temperature Shock/Hypothermia Protection: Many facilities are now considering the effects of low water temperature in relationship to the length of time a person will shower, or the combined effects of hypothermia and shock to the victim due to extended exposure to cold water (Remember: 15 minutes or more is required).

In line with the needs within the industry, ThermOmegaTech’ s Tempered Water Supply Systems are available as either a unit that mixes hot and cold water supply like the Therm-O-Mix® Station/WWM or a unit that utilizes plant steam through a proprietary heat exchanger loop to indirectly heat cold water, the Therm-O-Mix® Station.

Both have redundant controls for safety, and are self-contained; no electrical connections are required. The most common temperature requested is about 85°F (29°C); not warm enough to open the skin pores and not too cold to deter usage.


4. Freeze Protection: The second item under “Other Considerations” refers to freeze protection, mechanical and/or electrical. Many shower manufacturers offer heavily insulated and electrically heat traced shower designs. In some areas, electrical tracing cannot be used safely (due to explosion hazards), and potential power outages could well result in freeze damage.

A few manufacturers provide backup freeze protection on traced units by the addition of mechanical freeze protection valves while others (and many users) depend only on freeze protection valves equal to the ThermOmegaTech® HAT/FP and IC/FP designs. These valves start to open when sensing a fluid temperature of 35°F (1.7°C) or less, closing when the resupply water temperature reaches 40°F (4.4°C).


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