DOUBLE CHECK ASSEMBLIES MODELS 850 ... - Backflow Supply

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TROUBLE SHOOTING GUIDESymptom # 1Check fails to hold 1.0 PSID min.Cause:A. Debris on sealing surfacesB. Leaking shut-off valveC. Damaged seat or seat discD. Spring stem not moving freelySolution:Inspect and cleanInspect and clean, or repairDisassemble and replaceInspect for debris or damageSymptom # 2Chatter during flow conditions.Cause:A. Worn or damaged partsSolution:Inspect and replaceSymptom # 3Low flows passing through themainline valve.Cause:A. Mainline check fouledSolution:Inspect and clean, or repairCHECK MODULE DISASSEMBLY1. Slowly close inlet and outlet ball valves. Bleedresidual pressure by opening # 2, # 3, and # 4 testcocks. Allow the test cocks to remain open untilthe reassembling is completed. Test cock # 1should remain closed.2. Remove the cover bolts (item 21) using theappropriate size wrench.5. Remove the outlet check assembly by placing thetip of a medium size flat nose screw driver in theslot of the seat (item 3) and prying the checkassembly back until the red o-ring (item 3.1) isexposed. Then, using your fingers, pull it out fromthe body bore until it is completely exposed thenlift out of the body.3. Remove spacer (item 8) by grasping the flangedend of the spacer and pulling straight up.4. Remove the inlet check assembly by pulling it inthe direction of flow out from the body bore until itis completely exposed then lift out of the body.Page 4 FEBCO Model 850 / 850U ( 1 /2" - 2")
SEAL REPLACEMENTBoth check assemblies are disassembled andreassembled in the same manner. To service thechecks you may replace the check modules with newones by using check module assembly kits availablefrom FEBCO. Or, you may also replace the rubbercomponents in the check modules by using thereplacement rubber parts kits available from FEBCO.For details on parts and kits please see pages 6 - 8.1. To disassemble, grasp the seat section (item 3) inone hand and the guide section (item 7) in theother hand and then rotate in a counter clock wisedirection (approx. 1 /8 turn) until the two partsdisengage.CHECK MODULE RE-ASSEMBLYUse reverse procedure for assembly with the followingspecial instructions.1. Inspect the check module o-ring (item 3.1) fordamage and replace if necessary. To ease assembly,apply a thin coating of FEBCO factory suppliedpetroleum jelly (food grade) to the o-ring(item 3.1) prior to installing in body. CAUTION:Excess lubricant may cause foreign debris tocollect on internal components which could foulthe check assembly and result in a test failure.2. The word INLET is inscribed on the end of eachmodule. That end should face the inlet of thevalve.2. Remove retaining screw (item 5.2) and discretainer (item 5.1) so the rubber disc is fullyexposed. Carefully pry out the rubber disc frompoppet. Be careful not to damage the poppetwhen removing the disc. Rinse poppet in cleanwater and replace the old rubber disc with newrubber disc. If the rubber disc is not damaged itcan be reversed and reinstalled when a new discis not available. Rinse all other internal componentswith clean water. Replace disc retainer andsecure with retaining screw (item 5.2).3. When replacing spacer (item 8) between the twocheck assemblies be sure that the flanged end ofthe spacer is touching the back side of the inletcheck assembly so that the cover will fit properly.Next, replace cover making sure # 3 test cock is onthe upstream side. Do not over tighten cover bolts(Approximately 35 inch-pounds is sufficient).4. After reassembling, close test cock # 2, # 3 and # 4(test cock # 1 should already be closed), slowlyopen inlet ball valve. Bleed air from the unit byopening and closing test cock # 2, then # 3 andfinally # 4.5. Check for external leaks and repair if necessary.Slowly open outlet ball valve.6. Test assembly in accordance with the locallyapproved test methods.3. Reassemble check module in the reverse manneras indicated in above. When reassembling thecheck module be sure to insert the poppet steminto the guide hole and keep fingers clear of theslots in the module.FEBCO Model 850 / 850U ( 1 /2" - 2") Page 5
Page 2 and 3: TABLE OF CONTENTSFeatures and Opera
Page 6 and 7: EXPLODED VIEWCHECKMODULEPage 6 FEBC
Page 8 and 9: REPAIR KITSHow to order parts and R
Page 10 and 11: FEBCO PERFORMANCE, VALUE, AND QUALI
Page 12: WARRANTYAll products manufactured a

DOUBLE CHECK ASSEMBLIES MODELS 850 ... - Backflow Supply

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