BACKFLOW INSTALLATION, OPERATION & MAINTENANCE MANUAL BFMM DC4A SBF | EFFECTIVE AUGUST 1, 2016 Model DC4A / DCLF4A 1/2” - 2” Double Check Valve (DC) Backflow Preventer
INSTALLATION, OPERATION, & MAINTENANCE MANUAL TABLE OF CONTENTS Double Check Valve Backflow Preventer 1/2” – 2” Section Page I Description and Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 II Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
BFMM DC4A SBF DOUBLE CHECK VALVE BACKFLOW PREVENTER 1/2” – 2” I. DESCRIPTION AND OPERATION The Double Check Valve (DC) device consists of two independently-acting, spring-loaded check valves. Two resilient seated shutoff valves and four test cocks complete the assembly. Each check is designed to maintain a minimum of 1 psi across the valve during normal operation.
INSTALLATION, OPERATION, & MAINTENANCE MANUAL Figure 1 (FLOWING CONDITION) Figure 2 (NO FLOW CONDITION) NOTE: Pressures shown are for illustrative purposes only and are not necessarily indicative of any actual valve. 4 www.apollovalves.
BFMM DC4A SBF III. TROUBLE SHOOTING SYMPTOM 1. Check valve fails to hold 1 psid. CAUSE CORRECTIVE ACTION a. Shut-off valve not closed a. Close #2 shut-off valve or completely. inspect for possible through leakage. b. Check valve fouled with b. Inspect and clean seat debris. disc and seat. c. Check poppet stem not c. Inspect for debris or moving freely in guide. deposit on poppet stem or guide. IV. MAINTENANCE INSTRUCTIONS 1/2” – 2” A. Disassembly - Check Valves 1. 2. 3. 4. 5.
INSTALLATION, OPERATION, & MAINTENANCE MANUAL V. TESTING PROCEDURES This test is performed with the Differential Pressure Gauge Test Kit. The Differential Pressure Gauge simply measures the pressure drop across the check valve. This pressure drop is normally the same as the strength of the check valve spring. In using the Differential Pressure Gauge to test the Double Check assembly, a minimum of 1.0 psid is required for each check valve in order for that check valve to pass the test.
BFMM DC4A SBF TEST NO. 3 PURPOSE: To test leaking #2 shut-off valve As previously mentioned, the above test is not accurate when the second shut-off valve is leaking. The following test will expose a leaking shut-off valve. 1. Both shut-off valves should be open. Make sure all valves on test kit are closed. Connect the high “A” hose to test cock #2 and the low “B” hose to test cock #3. Open test cock #2 and test cock #3. 2. Open the high “A” valve and vent “C” valve to bleed air from high side of gauge.
INSTALLATION, OPERATION, & MAINTENANCE MANUAL PARTS LIST 1/2” – 2” Figure 4 8 www.apollovalves.
BFMM DC4A SBF DC4A and DCLF4A Parts List Item # Description Std. or LF 1 2 3 Body Label Plate Label Plate Tacks Test Cock M x F (81 metal) Test Cock M x F (Lead Free) Test Cock SAE (81 metal) Test Cock SAE (Lead Free) Cap (81 metal) Cap (Lead Free) Cap O-Ring Check Module O-Ring Check S-Assy (see below) All All All Std LF Std LF Std LF All All All 4 4a 5 6 7 8 Qty.
INSTALLATION, OPERATION, & MAINTENANCE MANUAL Inlet and Outlet Shut-Off Valves Item # Std.
BFMM DC4A SBF REPAIR KITS DC4A & DCLF4A 1/2” – 2” Check Module Rubber Kit (One kit repairs one check) (Universal, for standard & lead free valves) Item # not Shown 11 7 6 Repair Kit Model Number Ordering Number O-Ring Lubricant Check Module Seat Disc Check Module O-Ring Cap O-Ring DC Checks Complete Kit (One kit repairs one check) (Universal, for standard & lead free valves) Item # not Shown 8 7 6 extra part(s) Repair Kit Model Number Ordering Number O-Ring Lubricant Check Module S-Assy Check Module O-
Regional Management List now available online at http://conbra.co/rmlist 704.841.6000 800.395.7313 800.776.2756 www.apollovalves.com www.elkhartproducts.com www.lascofittings.
