38/Plumbing Engineer March 2021
However, these valves will not become extinct. ASSE 1017 valves can still ensure a uniform distribution tem- perature, even if it is higher than in the past. They also allow engineers to store water at high temperatures while distributing at a lower but still a "high" temperature. They can assist in reducing Legionella; however, engi- neers and owners must weigh the cost of an ASSE 1017 valve over the value it provides. A strong player in this market is the digital master mixing valve, which provides ASSE 1017 protection along with digital readout and data logging of inlet and outlet temperatures. It can be set to provide alarms upon failure and performance out of a specified tolerance. Many owners see the value in this information and sys- tem safety. Whether a mechanical or digital ASSE valve is used, the same considerations are still present: These valves are not intended for point of use appli- cations. Valves must be sized to match the following flow requirements of the system: Further mixing downstream is allowed to provide final temperature control to protect against scalding. These devices used alone do not provide thermal shock protection or adequate scald protection. TAFR Valves: The ASSE 1062 Valve Although not commonly used, a temperature-actuated, flow-reduction (TAFR) valve can be applied to a fixture outlet to reduce flow to a trickle within five seconds, in the event the outlet temperature exceeds a preset value, not to exceed 120 F. During the five-second response period, the bather may be exposed to temperatures in excess of the set-point of the device. Important to note is that these devices provide scald protection only; they do not provide thermal shock protection. TAFR valves are not intended to be installed in place of devices complying with ASSE 1016, ASSE 1017, ASSE 1066, ASSE 1069 or ASSE 1070. The 'Nonshower' Pressure-Balancing Valve: The ASSE 1066 Valve Another uncommonly used valve, the ASSE 1066 automatic pressure-balancing valve, can be applied like an ASSE 1016 valve for sinks, lavatories, etc. The 1066 is blind to incoming water temperatures and only provides thermal shock protection, not scald pro- tection. Since most codes require an ASSE 1070 valve used for handwashing, they do not have a very common application. Gang Shower Valves: The ASSE 1069 Valve For applications in locker room or penal showers, where individual shower valves are not used for safety and or anti-ligature applications, an ASSE 1069 valve can be used and connected directly to fixture outlets. The valve will determine the final temperature of everything connected downstream, and the end-user typically doesn't have access to the valve for temperature adjustment. The valves do, however, provide thermal shock and scald protection. Sink Faucets: The ASSE 1070 valve Water at handwashing applications should not surpass 110 F. Design engineers can use a mixing valve at the point of use to make this happen. The trick is specifying the right one. For sink, lavatory, bidet or bathtub applications, ASSE recommends using the ASSE 1070 valve. These devices are intended to supply tempered water to plumbing fix- ture fittings or be integrated with plumbing fixture fit- tings providing tempered water. This valve's successful performance depends on key factors such as a minimum flow rate and associated pressure drop. Additionally, a temperature deviation is required for the ASSE 1070 valve to work optimally. Here's what's necessary: Cold and hot water temperatures must come in at 10 to 15 degrees from the valve outlet set-point. For example, to maintain the 110 F water, the hot water at the valve must be a minimum of 125 F and cold water a maximum of 95 F. The ASSE rating allows for a deviation of the set- point, plus or minus 5 or 6 degrees. Most importantly, pair the performance characteristic with the value of the application. If LEED certification is a priority and the facility is outfitted with low-flow fix- tures, it's critical to know which valves to select should your facility be increasing the hot water temperature throughout the piping system. Raising your system's hot water temperature without considering mixing valves at regular faucets will put occupants at major risk for scalding. Emergency Fixtures: The ASSE 1071 Valve Emergency eyewash, eye/face wash and shower appli- cations typically operate at 85 F and work off an ASSE 1071 valve. The person engaging an emergency fixture will typically need to use it for 15 minutes. Thermostatic valves employed in emergency fixtures are paying atten-
Scalding
Previous Page