Product Overview

ES-F-765
S P E C I F I C A T I O N S H E E T
FEBCO product specifications in U.S. customary units and metric are approximate and are provided for reference only. For precise mea-
surements, please contact FEBCO. FEBCO reserves the right to change or modify product design, construction, specifications, or materials
without prior notice and without incurring any obligation to make such changes and modifications on FEBCO products previously or subse-
quently sold.
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Approval
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Engineer
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Series 765
Pressure Vacuum Breakers
Size:
1
⁄2" - 2" (15mm - 50mm)
The FEBCO Series 765 Pressure Vacuum Breakers are used to protect
against health hazard and non-health hazard backsiphonage conditions in
industrial plants, cooling towers laboratories, laundries, swimming pools
and lawn sprinkler systems.
Features
• Allbronzebodyfordurability.Onecheckvalveandanairopeningportin
one assembly.
• Lightweightpoppetsealsairopeningunderminimumflowconditions.
• Simpleserviceprocedures.Allinternalpartsserviceableinlinefromthe
 topoftheunit.
• Designedforminimumheadloss.
• Engineeredplasticbonnetprotectvalvebodiesfromfreezedamage.
• Optionalunionendballvalvesforeasyremovalandultimate
 freezeprotection.
• EndConnections–NPTANSI/ASMEB1.20.1
Operation
TheFEBCO765PVBisdesignedtobeinstalledtoprovideprotection
againstbacksiphonageoftoxicornon-toxicliquids.Itconsistsofaspring
loadedcheckvalvewhichclosestightlywhenthepressureintheassembly
dropsbelow1psiorwhenzeroflowoccurs,plus,anairreliefvalvethat
openstobreakasiphonwhenthepressureintheassemblydropsto1psi.
Specifications
Pressure Vacuum Breaker assemblies shall be in stalled to withstand
pressureforlongperiodsandtopreventbackflowofcontaminatedwater
into the potable water system in backsiphonage conditions. The Pressure
VacuumBreakerassemblyshallconsistofasinglespringloadedcheck
valvewhichclosestightlywhenwaterflowthroughtheassemblydrops
tozero,andasingleairreliefvalvethatopenstobreakthesiphonwhen
pressuredropsto1psi.Theassemblyshallincludetworesilientseated
shut-offsandtworesilientseatedtestcocks,consideredintegraltothe
assembly.Assembliesmustbefactorybackflowtested.Thecheckvalve
andairinletvalvemustbeconstructedtoallowin-lineservicingofthe
assembly.Thevalvebodyshallbeconstructedofbronze.Thecheck,pop-
petandbonnetassemblyshallbeconstructedofengineeredplasticto
protectthevalvebodyfromfreezedamage.
PressureVacuumBreakerassembliesshallbeinstalledaminimumof
12"(300mm)abovethehighestdownstreamoutlet,andthehighestpoint
inthedownstreampiping.Theassemblyshallberatedto150psiworking
pressureandwatertemperaturefrom32°Fto140°F.Theassemblyshall
meetthespecificationsoftheUSCFCCC&HRManual.
Pressure Vacuum Breaker assemblies shall be FEBCO Series 765 or prior
approvedequal.
Approvals – Standards
• ApprovedbytheFoundationforCross-ConnectionControlandHydraulic
 ResearchattheUniversityofSouthernCalifornia.
Applications
PVB assemblies are used to protect against health hazard and non-health
hazard backsiphonage conditions in industrial plants, cooling towers labora-
tories, laundries, swimming pools and lawn sprinkler systems.
Typical Installation
Pressure Vacuum Breaker assemblies should be installed at least
12"(300mm)abovethehighestpipingandoutletdownstreamofthe
assemblytoprecludebackpressure.Assembliesshouldbeinstalledso
theyareeasilyaccessibleformaintenance,periodictesting,andwheredis-
chargewillnotbeobjectionable.Theyshouldbeprotectedfromfreezing.If
theassembliesaresubjecttofreezingtemperatures,thefreezeprotection
proceduresoutlinedin"ServiceInstructionFreezeProtectionModel765"
mustbefollowed.Assembliesmustnotbeinstalledwherebackpressure
could occur.
Thedischargepressureshallbemaintainedabove3.0psion
1
⁄ 2 "-1
1
⁄ 4 "(15-32mm)sizesand5.0psion1
1
⁄ 2 "-2"(40-50mm)sizesto
insureseatingofthespringloadedairinletpoppet.
Thermalwaterexpansionand/orwaterhammerdownstreamoftheback-
flowpreventercancausepressureincreases.Excessivepressureshould
beeliminatedtoavoidpossibledamagetothesystemandassembly.
765
765 U
12" (300mm) above the highest downstream
outlet and the highest point in
the downstream piping
Flow
1020 B64.1.2