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AlIN1AlU�i INSTALLATION REQUIRE111ENTS <br /> FOR REDUCEU Pl2ESSURE BACKFLO�Y ASSEMBLIES <br /> Rcduccd Pressurc I3ackllow Asscmblics(RPBAs) consists oftwo indcpcndently acting spri�ig loaded <br /> check valves scparatcd by a spring loadcd diffcrcntial pressurc relicf valve, hvo resilient scated <br /> shutoIT vah�cs, and four properly locatcd, resilicnt scatcd tcst cocks. The RPBA shall confomi to <br /> A1V�'VA Slandard C511-89, the Univcrsity of Southem Califomia Foundation for Cross Connection <br /> Control and Hydraulic Rcsearch rcquiremcnts, and bc of a dcsign approved by thc lacal authority and <br /> statc regulatory agcncies. Mcchanical specifications for RPBAs can be found in ihe University of <br /> Southcm California Manual of Goss Conncction Cnmrol. Thc local aulhorities may havc strictcr <br /> standards of acccptance than do Ihose at a state Icvcl, and, will prcvaiL Approvcd assemblics will be <br /> fowid in lhc mosl currcn� 1Vashington Statc apnroved list undcr thc hcading "REDUCED <br /> PRESSURE I3ACKFLO�V PREVENTION ASSEII9BLIES." Thc RPDA is cffcctivc against <br /> backllow causcd Uy Uackpressure ancUor backsiphonagc and is uscd to protcct thc watcr systcm fmm <br /> substanccs which arc hazardous to hcalth. Thc folloH�ing infommtion in largc part �amc from thc <br /> currcnt Cross Conncclion Conlrol Manunl: Acccptcd Proccdurc and Practicc anJ has bccn updated <br /> in placcs to conform to thc local slandards as much as possiblc. [Cthcrc arc any qucstions in rcgard <br /> to this inlonnation plcasc call VVilliam Bn�cc at(425)257-8833. <br /> In all cascs, prior to installation, consult thc spccifications and mcommcndcd installation practiccs <br /> for tlic s ici cific manufacturcr's assembly to bc installcd. All asscmblics will fimction thc samc, but <br /> specific dilTerences in design (location oCtest cocks, relicf valve, etc.)will vary from manufactwcr to <br /> manufacturcr micl will nmkc inslallation slightly diffcrent frotn asscmbly to asscmbly. <br /> L Recluced Pressw•e Princinle 13ack11q�v Prevention Assembly1RPE3Al <br /> Thc rcduced pressurc principle Uack(low prcvention assembly shall be installed as a <br /> unit bchveen two TIGI ITLY closing shutoff valves as shown in the drawing(sec City <br /> ol'Lvcrctt slandard 518 at the end of this documcnt). During nonnal operation thc <br /> pressurc bctwecn thc t�co chcck vabcs is mainiained at a lo�vcr pressurc than thc <br /> supply pressurc. If eitlicr chcck ��alve shnuld Icak, the diflercntial pressure relief <br /> vah�e will maintain a nressurc dil7crcnlial of not Icss than 2 psi bcheecn the supply <br /> pressure and the zonc bchvicen dic two clicck t�alvcs by discharging watcr to thc <br /> atmosphcre. Tlic RPL3A is nonnally used in locations �vhere an appro�cd air gap is <br />, impractical. <br /> Inslallation Proccdures <br /> A. The RI'BA shall be inslallcd with adcquatc spacc to facilitate maintcnance and <br /> testing (see City of Evcrett standard 518 at the end of Ihis document). It shall be <br /> inspcctcd and tested aftcr installation to insure its satisfactory operation au�! proper <br /> installation. <br /> B. It is intportant that some models of 2PBAs be installed at least 12 inches, plus <br /> nominal size of the asscmbly, abovc finished [loor Icvcl, because the removal of the <br /> rclicf valve rcquires a minimum of 12 inchcs of cicarancc. Also, somc assemblics <br /> require a minimum ���all clearance for rcmoving thc pins Gom check vah�es. Again, <br /> consult lhe specific manufactumr's installation instiuctions and particularly the ciry's <br /> rcquiretncnts. <br /> ��� <br /> 5:\BBnxe\Backllow Installation Requirements 02ll09)ri.da <br />