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7� SPECIFICATION SHEET NO. (sjtt_2,t) Model 825Y 0/" through 2") Reduced Pressure Backflow Preventer For High Hazard Service Features • ultimate mechanical protection of potable water, against hazards of cross connection contamination. Shown with • Meets all specifications of AWWA, ASSE and Bail valve shut-offs. approved by the Foundation for Cross Connection Control and Hydraulic Research at the University of valve body from the line. All seat discs shall be reversible. Southerr. California. Shut-off valves and test cocks shall be full • rted ball Flo cure gener ted by the FoundaHydraulic Rof esearch The assembly shall be rated to 175 PSI water Working valves. Pressure and water temperature rangefrom 32°F to 140°F. at the University of Southern California. The assembly shall meet the requirements of ASSE Standard • Modular relief valve for ease of maintenance. Simple Service procedures. All internal parts Foundation for Standard r ssrCon Connection Control adnd approved ydraulicy the • serviceable in line. Hydraulic Research at the University of Southern California. • Low head loss. Typical Applications • Spring loaded "Y" type check valves. Reduced Pressure assemblies are used to protect against • Internal relief valve pressure sensin high hazard (toxic) fluids in water services to industrial • g passages. Replaceable relief valve seat ring on l%-', 1", 1 yZ They are also used in irrigation systems, boiler feed, water plants, hospitals, morgues, mortuaries, and chemical plants. and 2". lines and other installations requiring maximum protection. Operation Installation In a flow condition the check valves are open with the Reduced Pressure Backflow preventers should be installed Pressure between the checks, called the zone, being with minimum clearance of 12" between port and floor or maintained at least 5.0 PSI lower than the inlet pressure and grade. They must be installed where discharge will not be the relief valve is maintained closed, objectionable and can be positively drained away. They Should abnormal conditions arise under no flow or reversal of should be installed where easily accessible for testing and flow, the differential relief valve will open and discharge to maintenance and must be protected from freezing. Thermal maintain the zone at least 2 PSI lower than the supply. water expansion and/or water hammer downstream of the In resumption of normal floExcessive w, the zone's differential pressure pressure situations should be eliminated to avoid backflow preventer can cause excessive pressure.possible will resume and the relief valve will close. damage to the system and assembly. Typical Specifications Refer to local codes for specific installation nrequirements. The reduced pressure backflow preventer shall consist of two Some codes may independently operating, spring loaded, "Y" Y Prohibit vertical installation. valves and one hydraulically dependent differential rreliefck valve. The assembly shall automatically reduce the pressure in the "zone" between the check valves to at least 5 PSI lower than inlet pressure. Should the differential between the Side re upstream and the zone of the unit drop to 2 PSI, the EExo differential relief valve shall open and maintain the proper M°a�836Y PMtecnve differential. Endo,.,. Mainline valve body and caps including relief valve body and 17o Ma. } cover shall be bronze. Check valve mo water Meter center stem guided. All hydraulic sensing g member shall be internally located within the mainline and grel repaslief aloe bod31 ies u / and relief valve cover. Diaphragm to seat area ratio shall be 10:1 minimum. Relief valve shall have removable seat ring. Check valve and relief valve components shall be constructed so they may be serviced without removing the SS 825Y 2"4/95