Distribution System Hydrants and Valves

1 Hydrants and Valves American Water College1 American Water CollegeDistribution ReviewFire Hydrants and Valves American Water CollegeHydrant and Valve Training ObjectivesTo gain an understanding of:The construction of the four main types of hydrantsGate valve construction and usesGlobe valve construction and usesBall valve construction and usesButterfly valve construction and usesRelief valve construction and usesPressure regulating valve construction and usesAir and vacuum relief valve construction and usesAltitude valve construction and uses American Water CollegeFire HydrantsTypes of Fire HydrantsDry BarrelWet BarrelWarm ClimateFlush HydrantHydrants and Valves American Water College2 American Water CollegeFire HydrantsDry barrel HydrantUsed in locations that freezeMain valve is located below groundDrain valve allows water to drain from barrel when the main valve is closed American Water CollegeFire HydrantsWet barrel HydrantFilled with water all the timeNot used in locations that freezeHas separate valve for each nozzleNo main results when hydrant is hit and damaged American Water CollegeFire HydrantsWarm Climate

2 HydrantMain valve is at ground levelMain valve controls flow from all nozzlesHas no drain mechanism in upper barrel and is pressurized in the lower barrelHydrants and Valves American Water College3 American Water CollegeFire HydrantsFlush HydrantUsed where an above ground hydrant would be objectionableAirport taxi-ways, pedestrian mallsCompletely below groundAccessible through cover American Water CollegeFire HydrantsInstallation and PlacementPlaced 2 feet off curbFed by a minimum main diameter of 6 inchesAn auxiliary valve should be installed between hydrant and mainA breakaway flange should be installed 2 inches above ground surface American Water CollegeValvesGate ValveDesigned to start flowNot used to throttle flowDisc is raised into the bonnetMinimal head loss when openLarge Valves have equalizing lines or bypass Valves for use prior to openingHydrants and Valves American Water College4 American Water CollegeValvesGate Valve Partshand wheelyokestembonnetdisc (gate)seat American Water CollegeValvesTypes of Gate ValvesRising stem (outside screw and yoke)

3 Non-rising stemHorizontalResilient wedge American Water CollegeValvesGlobe ValveCommonly used for household plumbingNot well suited for Distribution System mains due to head lossUsed where head loss is not a concernCan be used to throttle flow and control downstream pressureHydrants and Valves American Water College5 American Water CollegeValvesGlobe Valve Partshand wheelbonnetstemstuffing boxback seatdiscseat American Water CollegeValvesBall ValveUsed as isolation valvesMinimal head lossNot used to throttle flowFully open/shut with turn American Water CollegeValvesBall Valve Partsstem/operatorball seatHydrants and Valves American Water College6 American Water CollegeValvesButterfly ValveDesigned to start/stop flowHigh pressure throttling will damage discFaster operation than gate valvesUsed primarily at pump stations and treatment plants American Water CollegeValvesCheck ValveAllow flow in one directionUsed at pump dischargesFoot valveis a special check valve on pump suctionsSlamming check valve can cause water hammer.

4 Some are designed with restraints to limit slamming American Water CollegeValvesCheck ValvesSwing CheckBall CheckCushioned Swing CheckHydrants and Valves American Water College7 American Water CollegeValvesPressure Relief ValveUsed to prevent overpressure and dampen water hammerSystem pressure must overcome spring tension to open valveThis type used primarily on positive displacement chemical feed pumps Also used on water heaters and boilers American Water CollegeValvesPressure Reducing ValveUsed to reduce pressure from a higher pressure zone in order to provide water to a lower pressure zone by throttling flowPilot System automatically controls valve operation American Water CollegeValves Upper Pressure ZoneMiddle Pressure ZoneLower Pressure ZonePressure ReducerPressure ReducerHydrants and Valves American Water College8 American Water CollegeValvesAltitude ValveUsed to control storage tank levelSingle acting Valves allow flow in one direction Double acting Valves allow flow in two directions single-actingdouble-acting American Water CollegeValvesAir and Vacuum Relief ValveAir in System can reduce flow as much as 15%Automatically vents air at high points in the systemAllows air in to break vacuum in System to prevent pipe collapse while draining American Water CollegeValvesNew Service Tap Known as a corporation stop Usually a ball valve but could be a plug valveTapped with System pressurized to prevent contaminationTapped at 45oangle down from top center of pipe to minimize air and sediment entrySaddle used to prevent damage to pipe when installing the new valveHydrants and Valves American Water College9 American Water CollegeValves American Water CollegeValvesCurb Stops and Boxes Curb StopMain shutoff for water serviceInverted plug valve or ball valveLeaks common when operating old connectionsCurb BoxArch-style Fits loosely over meter

5 And curb stopMovement of box will not affect water lineMinneapolis-stylePrevents misalignment by connecting to curb stopDamage to box may damage supply line American Water CollegeReview the lecture handout and then complete the quiz. This will help you remember the information we just covered.