Written by Sean Cleary 4:26 pm Backflow Prevention

The Ever-changing Backflow Industry

The focus of this issue of Working Pressure is “New Technology.” In the backflow industry, changes occur all the time. Existing product standards are revised and updated, new products are introduced, and new product standards are created. Codes are revised and updated on a three-year schedule. Anyone working in the industry needs to stay current on standards, codes, and local regulations that may or may not be updated on a regular schedule.

As an example, let us look at the development of vacuum breakers over time. We began with atmospheric vacuum breakers (AVB) that have been in use for over one hundred years. (1) It is a simple device that provides high and low hazard protection against backsiphonage. As plumbing and mechanical systems became more complicated, it became clear that these systems needed protection that the AVB could not provide. As a result of the AVB’s limitations, the industry developed the pressure vacuum breaker (PVB). The PVB provided the same type and level of protection as the AVB, and because of the design changes, the PVB could be under continuous or constant pressure. The AVB cannot be subjected to supply pressure for more than 12 hours in a 24-hour period and, as such, was unable to function under continuous pressure or with valves downstream of the AVB. (2) Problems with the PVB discharging water in low pressure situations resulted in the development of the spill-resistant vacuum breaker (SVB). All three vacuum breaker types – the PVB, SVB, and AVB – protect against high and low hazard backsiphonage backflow, but each has strengths or weakness that do not allow them to be used in every situation. (3)

Many upgrades to the products we use to prevent backflow are nothing short of amazing when you look at where our industry was 20 or 30 years ago. Assemblies are shorter, weigh less, contain less parts, are easier to repair and maintain, and can be installed in so many different orientations. I remember in the 1990s when we were working in existing mechanical rooms attempting to find the room to install a six- or eight-inch reduced pressure principle or a double check valve assembly as containment protection. Everything had to be installed horizontally and these flanged assembles were five to six feet long. Mechanical rooms are non-revenue generating space in a facility and tend to be as small as possible. Finding six to eight feet of horizontal pipe directly after the building water meter or before the alarm check on a fire protection system was not a common occurrence. This resulted in some interesting and many times incorrect backflow assembly installations. (4)

The first N pattern valve was a life saver in many tight spaces. Looking at all the assemblies and patterns available now, it is clear we live in an ever-changing industry. Even the shut off valves on assemblies are different and progress has been made to improve the products. Years ago, almost everything 2 ½ inch and larger had flanged connections and gate valves. There were a few assemblies available with ball valves, but butterfly valves on backflow prevention assemblies did not exist. Today, we have approved assemblies which use integral butterfly valves within the valve body allowing the lay length to be even smaller. (5) Who would have believed back then that a six-inch reduced pressure principle assembly could be 28.4 inches in total lay length.

We now have threaded, flanged, press-fit, and grooved connections on assembly shutoffs. We have assemblies approved for vertical up-flow, vertical down-flow, N-pattern, horizontal, and several other flow patterns. Several manufacturers make assembles specifically for fire hydrant use. We have alarm switches on relief valves and assemblies with solenoid valves to turn off the water supply in the case of large relief valve discharge. The industry is always innovating and looking for that better mouse trap.

Detector assemblies have also changed in recent years with the addition of the type two double check detector assemblies and type two reduced pressure principle detector assemblies. The development of these assemblies was driven by a search for both cost savings and a drive to lower pressure and friction loss. These assemblies use a single check in the bypass portion of the assembly instead of a double check or reduced pressure principle assembly. In a traditional detector assembly, the bypass piping comes off the assembly upstream of the first check of the main valve. In the type two assembly, the bypass begins downstream of the first check so although the bypass only contains a single check, it is protected by both the first check of the main valve and the bypass single check providing double check protection. With the reduced pressure principle assemblies, the bypass comes off downstream of the first check and in the reduced pressure zone, so the assembly does provide high hazard protection. As a result of the single check valve, there has been some confusion among testers and water purveyors on the proper testing of the type two assemblies and also with the proper completion of test forms for these assemblies. But the industry is adapting and moving forward with the use of type two assemblies. (6)

Even the systems we install backflow prevention on are different than in the past. While the laws of physics will never change, our systems do. The expanded use of gray water and recycled water was mostly unheard of even 15 years ago in most areas of the United States. All that has changed, the use of recycled water for water closets and urinal flushing, irrigation, and fire protection is now commonplace. Rainwater catchment for potable and non-potable use is a growing part of the industry. Testers now may need multiple kits to allow them to test on both potable and non-potable assemblies.

Our test kits are also evolving over time. We have moved from water column site tubes and duplex gauges to analog test kits, to digital test kits, to digital test kits with printers, to now digital test kits with download capability. Again, the laws of physics do not change, and all of these test kit types can and still are used with the possible exception of the duplex gauge. Which type of gauge a tester uses depends on personal preference and, in many cases, is a result of the gauge they used in their training class or the gauge type their employer has provided them with. Prices can range from several hundred dollars to thousands of dollars for the gauges with download capability. Any gauge used needs to meet minimum accuracy criteria and have its calibration checked annually at a minimum.

Innovation and change are a fact of life in any industry and the cross-connection control industry is no exception. Those of us working in the industry need to stay current with codes, regulations, and product changes. We need to embrace improvement in products and services and look at things with open eyes and open minds. As President John F. Kennedy once said, “Change is the law of life, and those who look only to the past and present are certain to miss the future.” President Kennedy was correct – we need to move forward so we don’t get left behind.

Article first published in Working Pressure magazine

Sean Cleary
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Sean Cleary has been a member of United Association Local 524 Scranton, Pa. for more than 40 years. He has worked in all phases of the plumbing and mechanical industry, and is a licensed master plumber. Cleary is a past president of ASSE International and past chairman of the ASSE Cross-Connection Control Technical Committee. He is employed by IAPMO as the vice president of operations for the Backflow Prevention Institute (BPI).

Last modified: December 19, 2023