[Editor’s Note: This month’s Tech Topic column strays from the usual Q&A format you’ve come to expect. Instead, we’ve gone to an expert in the field of backflow—Shannon M. Corcoran—to provide us with an update on the work being done to develop a more unified set of standards for backflow prevention assemblies.]

During the Society of Sanitary Engineering’s annual meeting in September 2006, the Society was asked to consider reopening four of its recently published standards for revision.
    These four standards, ASSE 1013, 1015, 1047 and 1048, are the plumbing industry’s consensus standards for reduced pressure principle backflow preventers, reduced pressure principle fire protection backflow preventers, reduced pressure detector fire protection backflow prevention assemblies, double check backflow prevention assemblies, double check fire protection backflow prevention assemblies, and double check detector fire protection backflow prevention assemblies.        
    The reason behind the request was simple—the backflow manufacturing community wanted a set of all-inclusive performance standards for North America developed in an open consensus process.
    In January 2007, an industry forum on testable backflow prevention assemblies sponsored by the American Society of Sanitary Engineering, the American Backflow Prevention Association, and the International Association of Plumbing and Mechanical Officials was held in Westlake, Ohio. Representatives from all segments of the plumbing and water industries were represented. The purpose of the forum was to determine what the industry saw as the future of backflow, including manufacturing trends, codes, regulatory enforcement, standards, product certification, and professional certification.
    The consensus of the attendees resulted in several recommendations being made to ASSE, including:

    •    Industry standards should be harmonized to eliminate duplicative testing, using the most stringent requirements from each standard.
    •    Individual certification agencies would utilize a consensus standard for the basis of their approval.•    A single set of voluntary, consensus standards needs to be developed encompassing all aspects of backflow that is open equally to all industry segments.
    •    Certification agencies should develop a list of approved laboratories that data will be accepted from for product certification purposes.
    •    Certification agencies should develop harmonized laboratory test report formats.•    A one-year field test provided valuable proof that the backflow prevention assemblies functioned long-term as intended.

    The first step in revising these four standards was to determine what needed to change. A comparison of all of the backflow industry standards and North American requirements were compiled, denoting the differences between the documents.    
    The standards and documents reviewed included the ASSE product standards, the CSA International’s B-64 standards, the USC Manual, 9th edition, the AWWA C510 and C511 standards, the UL requirements for backflow on fire protection systems, and the FM Approvals requirements for backflow on fire protection systems. In all, eighteen different performance tests were evaluated. Some of these tests apply to any assembly regardless of installation location (potable water system vs. fire protection system). Other tests are applicable only to assemblies installed on fire protection systems. Some performance tests are for RP/RPF/RPDA assemblies only, while others are for DC/DCF/DCDA assemblies only.    
    What were the performance tests and how are the various standards and protocols different?
   
    Hydrostatic Test of Assembly: The hydrostatic test of device subjects the assembly to an elevated working pressure to condition the assembly.   
    ASSE, USC and CSA all require the assembly to be tested at two times the maximum rated working pressure or at a minimum of 300 psi for five minutes. AWWA also requires the assembly to be tested two times the maximum rated working pressure or at a minimum of 300 psi; however, their test is for ten minutes, and during the test, the inlet pressure drops from 150 psi to atmospheric, and is then returned back to 150 psi – without damage. The UL requirements test the assembly at two times the maximum rated working pressure or at a minimum of 350 psi.    
    The test is run until the assembly is stable, or for at least 15 seconds. FM tests the assembly at two times the maximum rated working pressure, and requires that the diaphragm not sustain damage during the test.

    Cycle Test: The cycle test simulates actual use in the field. Only USC and ASSE require a cycle test during the laboratory testing. The assembly is cycled 1250 times at 25 percent of full flow, 50 percent of full flow, 75 percent of full flow, and 100 percent of full flow.

    Field Test: The field test involves the installation of the assemblies in various field locations where they are monitored and tested for a one-year period. AWWA and USC are the only agencies to require a mandatory one-year field test on three assemblies of each size. ASSE and CSA allow the manufacturer to perform either the one-year field test on three assemblies of each size or the laboratory cycle test. Both ASSE and CSA accept the USC Field Test for compliance purposes.

    Pressure Loss at Rated Flow Test: The purpose of this test is to determine the pressure loss through assembly at any flow from 0 GPM through the assembly’s rated flow. ASSE, AWWA, CSA and USC procedures allow the maximum pressure loss to be determined by the size of the assembly when tested from 0 GPM to 100 percent rated flow. UL’s test takes the assembly to 150 percent of rated flow, and FM’s test is measured at 0 to 30 feet per second.    

    Drip Tightness of the Checks Test: AWWA, CSA and USC test to ensure that the static pressure drop across the first check is at least 3 psi greater than the pressure differential between the inlet line pressure and the zone pressure required to open the relief valve. ASSE, AWWA, CSA, and USC all require that the second check prevent flow at 1 psi.

    Zone Pressure vs. Inlet Pressure at Static Pressure Test: ASSE, AWWA and CSA all require the zone pressure to be a minimum of 2 psi less than the inlet pressure.

    Relief Valve Opening Test: On RP, RPF, and RPDA assemblies, the relief valve should open when the pressure in the intermediate chamber or zone is 2.0 psi for RP assemblies and 1.0 psi for RPF and RPDA assemblies.

    Backsiphonage Test: The purpose of this test is to ensure there is no backsiphonage of water from the downstream piping into the supply line when both checks are fouled and a vacuum is created. A fouling wire is used to foul the checks open for this test. ASSE and CSA test the assembly using a vacuum on the inlet only, whereas USC also applies a backpressure on the outlet.

    Deterioration at Manufacturer’s Extremes of Temperature and Pressure Ranges: The purpose of this test is to subject the assembly to its high and low rated pressures, and to its high and low rated temperatures to ensure that these conditions will not adversely affect the assembly.

    Body Strength Test: (For assemblies on fire protection systems). Only CSA, UL and FM require a body strength test. CSA and UL require assemblies 6 inches and smaller to be tested at 875 psi or 5 times the maximum rated pressure; and assemblies 8 inches and larger to be tested at 700 psi or 4 times the maximum rated pressure for one minute. FM requires the assemblies to be tested at 4 times the maximum rated pressure for 5 minutes without damage.

    High Velocity (Endurance) Test: (For assemblies on fire protection systems). Only FM requires an endurance test conducted 30 feet per second for ninety minutes.    

    Now that the working group has reviewed and determined the differences between the tests, their next step is determining which requirements and performance tests were the most relevant. The working group is still in the process of determining what will be included in the four ASSE product standards.
    There are many more steps to be completed before the revision of these standards is complete. The working group must approve the drafts by a consensus vote of members. Once the working group approves the drafts, they are sent forward to the ASSE Product Standards Committee for their review and consideration.    
    The Product Standards Committee must approve the drafts by a consensus of two-thirds of the committee before it is submitted to the ASSE Board of Directors and the American National Standards Institute for their review and consideration in making these standards not only ASSE Standards, but the American National Standards for the backflow industry. How long will it be before you, the industry and public, see these standards? The working group members would like to see the revision process of these four standards completed by the end of 2008.