The Pressure Is On

July 18, 2014

Protecting the integrity of buildings’ plumbing systems

zurn_backflow prevention
Systems such as this one, which bundles three separate components that detect and shut down discharging backflow preventers.

Water efficiency and sanitation for a building or campus, whether new construction or retrofit, are best achieved through a whole-building approach, with a proper emphasis placed on connectors that regulate pressure.  

A building’s plumbing system is subject to numerous events that affect pressure — some routine, but others unpredictable, such as line distribution breaks or high water withdrawal rates. These events can result in back-siphonage that places potable water safety at risk.

In addition, irregular pressure can overtax a system’s integrity. One of the leading causes of water leaks is high pressure that exceeds the upper range for which the system was designed. The latest figures from the U.S. Environmental Protection Agency demonstrate that water leakage accounts for more than 6% of a facility’s water usage.

Automatic Control Valves

Solutions to address pressure regulation have reached a high level of sophistication. Building on the basic pressure-reducing valve that has been the hallmark of engineered water solutions, the latest roster of available automatic control valves (ACVs) addresses multiple end connection options, pressure ratings, ANSI/AWWA standards and functionalities. They cover a wide range of applications and uses, including commercial, education, healthcare, industrial, irrigation, penal, retail, waterworks and fire protection. 

Manufacturers are reacting to a multitude of end user requirements for water efficiency while still providing the performance and reliability of the core pressure-reducing valve. 

ACVs now on the market include the following types and features: 

  • Solenoid shutoff; 
  • Surge protection; 
  • Solenoid control; 
  • Non-modulating valve; 
  • Fire pump pressure relief valve; 
  • System/pump protection check valve; 
  • Pressure reducing with low-flow bypass; 
  • Pressure reducing with pressure sustaining; 
  • Excess pressure shutoff valve; 
  • Pressure relief/pressure sustaining;
  • Fire protection pressure-reducing valve; and
  • Fire protection pump suction control.

With this variety of ACVs now available to building owners and managers, plumbing professionals and manufacturers can recommend which products are best suited to each facility to improve water efficiency and save money.

Backflow Preventers

Another vital component of a plumbing system is backflow prevention — and, again, there have been some new developments that have brought innovation and a breadth of variety to this category. 

One new product is ideal for existing low-pressure systems. Made of stainless steel and featuring a large diameter, this backflow preventer is lightweight and corrosion resistant. It offers a machined check positioning sleeve, eliminating weld-seam leaks; checks that are retained securely, providing stable pressure with faster test results; a flow clean sensing passage to eliminate debris buildup in the sensing line; and a short lay-length that allows for installation into smaller spaces. It is available in four functional categories: double check assembly, reduced pressure assembly, double check detector assembly, and reduced pressure detector assembly.

Backflow preventers can be installed inside or outside a building. For interior spaces, such as mechanical rooms, backflow preventers should be equipped with a bundled, integrated flood control system to protect against flood risk/liability. Flood from a code-mandated reduced-pressure device installed indoors, even when working properly, can result in millions of dollars in cleanup and downtime. 

Components should include a reduced-pressure principle assembly with integral relief valve monitor with a monitor switch that senses a discharge; an electronic solenoid timer that processes any signal from flood sensing equipment against a settable time function (to eliminate nuisance trips) and, in the case of a fault, sends a signal to a solenoid valve and/or alarm device; and a solenoid actuated ACV that shuts off water through the system.

This new type of backflow preventer typically is shipped fully assembled for turnkey installation in retrofit and other projects. Accessories include additional cables to wire parallel bypass systems and/or backpressure shutoff valves.

It is crucial to keep up with current technology. An 8-in. backflow preventer at 100 psi can discharge 600 gal per minute (gpm), quickly overwhelming a mechanical room’s floor drainage system. One incident made headlines in 1994, when a Syracuse, N.Y., hospital’s mechanical room was inundated with 100,000 gal of water from a backflow discharge. The water filled the room to a height of 8 ft and caused extensive equipment failures. Patients were evacuated, and one died in transport. The domestic water supply was contaminated as a result. Cleanup and patient transfer costs were put at more than $2,000,000.

A separate incident, cited by the American Backflow Prevention Assn., occurred at a Fort Collins, Colo., hospital in 2001. An 8-in. double check backflow preventer blew, causing thousands of gallons of water to dump into the basement maintenance building, “knocking out the hospital’s telephone lines and computer systems, and causing evacuations.” In the equipment room where the break occurred, workers found 4 ft of standing water, and other rooms also were flooded.

For backflow preventers installed outdoors, a freeze-prevention device is essential in areas where occasional (and unexpected) freeze/thaw cycles occur, yet winterization (e.g., draining the system) is not common. A freeze- protection device monitors the water temperature within the valve. When the temperature-regulating thermostat senses that water is nearing the freezing point (35°F/1.6°C), the valve opens, allowing warmer supply water to flow into the system. As the system reaches 40°F/4.4°C, the valve closes.

A useful feature of this device is its compact design, which makes it easy to install on new and existing installations on virtually any brand of backflow preventer without the need to shut down or drain the system. Its bronze body is corrosion resistant and requires no periodic maintenance. It is suited for double check and reduced-pressure assemblies, vacuum breakers and bypass detector assemblies on large backflow products. It also can be used to protect other mechanical equipment, including any smaller-diameter commercial or residential outdoor plumbing systems to prevent pipe, pressure-reducing valves, shutoff valves or fixtures from freezing.

Water Hammer Arrestors

Finally, in a discussion of connectors that regulate water pressure, we cannot fail to mention water hammer arrestors. The latest models are designed for commercial and light commercial applications, feature all-copper and -brass external construction, are low-lead compliant, and have permanently sealed air chambers. Never overlook the need for these, because water hammering is more than a noise nuisance — it often can result in extensive damage, including pipe collapse.

A plumbing system, depending on the size of the project, can have thousands of points of connection that impact a building’s water efficiency and sanitation. It is impossible to achieve a water plumbing system impervious to changes in pressure, but it is possible to design a system with pressure regulation as a governing characteristic of its reliability. It is prudent for any new or retrofit project to reduce water usage and enhance water sanitation as much as current technology allows. Contact your plumbing product supplier to learn how you can save water and reduce risk.

Ezra Phillips is director of product management for Zurn Wilkins. Phillips can be reached at ezra.phillips@zurnwilkins.com or 805.226.6220.

  • zurn_backflow prevention
    zurn_backflow prevention
    Systems such as this one, which bundles three separate components that detect and shut down discharging backflow preventers.
  • zurn_backflow prevention_freeze prevention
    zurn_backflow prevention_freeze prevention
    This setup in Lake Elsinore, Calif., displays proper ventilation of a backflow preventer equipped with freeze-protection device.
  • zurn_automatic control valve
    zurn_automatic control valve
    New automatic control valves build on the technology of the basic pressure reducing valve.

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