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1111NIn1U111 INSTALLATION REQUIRE�tENTS <br /> FOR REDUCED PRESSURE BACKFLON ASSEMBLIEti <br /> Rcduced Pressurc Dackllow Assemblics(RPBAs) consists of avo indcpcndcndy a�ling spring loadcd <br /> chcck ��ah�es scparated by a spring ioadcd ditlercntial pressurc relief valve. hvo resilient scaled <br /> shutoff valves, and four properly located, resilient scated test cocks. The RPBA shall confonn to <br /> AWWA Standard C511-89, thc Univcrsity of Southcrn Califomia Foundation for Cross Connection <br /> Control and Hydraulic Rescarch rcquircmcnts, and be of a design appro��ed by the Iceal au(hority and <br /> state regulatory agencics. Mechanical specifications for Rf'BAs can be found in the Uni��crsity of <br /> Southcm Calilomia Manual of Cross Connection Control. The local authorities may have stricter <br /> standards of acccptancc than do thosc at a state Ievel, and, will prcvail. Approved assemblies will bc <br /> faund in thc most currcnt Washington State approved lis[ undcr thc hcading "REDUCED <br /> PRESSURE BACKFLOW PREVENTION ASSE1116LIES:' The RPQA is etTecti�•c against <br /> back(low caused by backpressure anci/or backsiphonage and is uscd to protcct the water systcm from <br /> substances �vhich arc hazardous to hcalth. Thc following information in largc part camc from thc <br /> currenl Crotiti Conncction Control Manual: Accepted Procedure and Practice and has becn updated <br /> in placcs to confonn to the local standards as much as possible. If Ihere are any qucstions in regard <br /> to this infonnation plcasc call William Brucc at(425)257-8833. <br /> In all cases, prior Io installation, consult the specifications and recommended installalion practices <br /> for thc s ccific manufacturcrs asscmbly to bc installcd. All asscmblics will function the samc, bid <br /> spccific diffcrcnccs in dcsign (Icxation of tcst cocks, rclicf valvc, ctc.) will vary from manufacmrcr to <br /> manufacturcr and will makc installation slightly diffcrcnt from asscmbly to asscmbly. <br /> I. Reduced Pressure Princinle IIacktlow Pre��ention Assembly(RPBA) <br /> Thc rcduccd pressurc principlc backtlow prevcnlion assembly shall be installed as a <br /> unit bchsccn two TIGFITLY��losing shutoff vah�cs as shown in thc drawing(scc Ciry <br /> of Gvcrclt standard 518 at thc cnd of this document). During nonnal operation thc <br /> pressurc bctwccn thc hvo check valves is maintained at a lowcr pressurc than the <br /> supply pressure. If either check valve should Icak, the diffeccntial pressure relief <br /> valvc will maintain a pressurc differcntial of not Icss than 2 psi bctween the supply <br /> pressurc and thc zonc bct�t�ccn thc hvo chcck ��alvcs by discharging water to the <br /> aunosphcrc. Thc RP13A is nornially uscd in locations ���hcre an approvcd air gap is <br /> impractical. <br /> Installation Proccdures <br /> A. Thc RPI3A shall bc insiallcJ �vith adcquatc spacc to facilitatc maintenancc and <br /> tcsiing (scc City uf Lvcrctt standard 518 at thc cnd of this documcnQ. It shall be <br /> inspcctcd and testcd atier installation to insure its satisfactory� operation and proper <br /> installation. <br /> I3. It is important that somc modcls oC RPBAs be installed at Icast 12 inches, plus <br /> nominal size of the assembly, above finishcd Iloor levcl, because lhe removal of the <br /> rclicf valvc requires a tninimum of 12 inches oC clearance. Also, some asscmblics <br /> rcquire a minimum wall dcarancc for removing the pins from check valves. Again, <br /> consult thc specific manufacturcr's inslallation instructions and particularly thc city's <br /> rcquircmcnts. / <br /> � �p <br /> 5:\88ruce\Backflow Installatlon Requirements 021709 jm.doc <br />