Apollo Valves DC4A Manuale di installazione, funzionamento e manutenzione - Pagina 3
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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 shut-
off 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 . If at any time the pressure downstream of the device increases above the supply pressure, both check
valves will close to prevent any backflow from occurring . The flowing and no flow conditions are illustrated in figures 1 and 2 .
To initiate flow, supply pressure must be sufficient to open both checks and overcome friction, normally a minimum of 3 to 5 psi
above the downstream pressure .
II. INSTALLATION
A . The DC must be installed in an accessible location to facilitate periodic field testing and maintenance .
B .
Flush all upstream piping thoroughly to remove foreign matter prior to installing the device .
C . The device should be installed either horizontally or vertical up for ease of maintenance and testing . A clearance between
the lower most portion of the device and flood grade or floor should be provided for ease of maintenance .
D . When shut-off valves are provided separately, they should be installed with a test cock on the upstream side of the inlet shut-
off valve .
E .
After installing the assembly and with downstream or #2 shut-off valve closed, pressurize the device and bleed ALL air
through test cock #4 . Then open #2 shut-off valve .
Customer Service (704) 841-6000
www.apollovalves.com
BFMM DC4A SBF
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