Technical Support

Every month our customer service department will post one new question that has come up during the month that they believe will may help you troubleshoot an existing product or provide insight on a new product available.

Q: Can I use any mixing valve with emergency fixtures? And what is by-pass flow rate?
A: No, you cannot use a “standard” thermostatic mixing valve with emergency fixtures (i.e. eye wash or drench shower). Most “standard” thermostatic mixing valves have inherent design features where if there ever was a failure of hot or cold to the inlets, the valve will reduce the output flow to a low flow. This scenario is very undesirable for emergency applications. Part of the principle behind emergency fixtures is to ensure that if someone has been exposed to hazardous materials always has water available to them to flush out the hazardous materials. All emergency mixing valves are specifically designed to be used with emergency eyewash/face wash/ and drench showering equipment. One of the unique features of this type of mixing valve is the integral cold water by-pass. The by-pass guarantees a minimum flow rate be delivered by the mixing valve with the cold water supply pressure as low as 30 PSI and the hot water supply pressure 0 or shutoff. For these applications, ANSI Z358.1 states that you must provide tepid (60-100°F) to the fixtures and emergency mixing valves provides a means to attain the designated temperature. Please note that ANSI provides a broad range because these are many chemicals in the market, and some may require a higher or lower temperature to provide soothing to the affected person. A Safety Compliance officer should consult a medical professional to confirm the appropriate drenching temperature based on their specific needs.

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