Design Problems for a Simple Rural Supply System簡(jiǎn)單的農(nóng)村供水系統(tǒng)設(shè)計(jì)手冊(cè) 2

1/1DesignProblemsforaSimpleRuralSupplySystem簡(jiǎn)單的農(nóng)村供水系統(tǒng)設(shè)計(jì)手冊(cè)2a.Iftheflowofthesourcewere5.0l/sthenallofthiswaterwouldflowtothereservoirif4inchpipewereinstalled.HOW-ever,thepipewouldbeonlypartiallyfullofwater.b,Theavailableheadfromthesourcetothereservoirisapproxima-tely55meters.Onthewaterflowcalculator4inchGIpipeforadistanceof2,000mbtersandaheadlossof55metersindicatesaflowofapproximatelyI2l/s.Thusa4inchpipecouldnotlccoamodatethefullflowofthesourceandtheexpectedflowatthereservoirwouldba12l/s..c.Usingthewaterflowcalculator,3inchGIpipeforadistanceof2,000metersandaflowof5.0l/sindicatesaheadlossofapproximately48meters,Theavailableheadisapproximately55meters.Thus,3inchGIpipeissuitablefortherequiredflow.IP-75.Giventhegroundprofileinthefigurebelowchooseanayproprbtepipeeizeforaflowof2l/sfromthesourcetothereservoir,PlottheHGL.S.13.Theavailableheadfromthesourcetothereservoirisapproximately35meters.Usingthewaterflowcalculatorthefolluwingvaluesareobtainedforaflowof2l/eusingGIpipe:.?’-10-Distancepipediameter(meters)(inches)headlose(meters),ooo2.57,ooo230l,QOO1.5qwThusa2inohGIpipe16suitable.TheHGLisplottedonthefigurebelow.P.14.GiventhegroundprofileanddesignflowinthefigwebelouchooseappropriateGIpipe.PlottheHGLforthepipeaelected.S.14.Usingthewaterflowcalculatorthefollowingvaluesareobtained:%tance(meters)flow(lb)pipediameterheadloss(inches)(meters)d=J12.521~129,oOfJ11.5361,m0.522-51.m0.57.5101,0600.51.2524Thetotalavailableheadieapproximately20meters.Thusacombi-nationof1,000metersof2inchand1,000metersof1.5inchpipaisappropriate.TheHGLieplottedinthefigurebelow.\,0002,0000ISIrnt4CEwwm%s)P.15.GiventhegoundprofileinthefigurebelowplottheRGLforadesignflowof4l/ousing3inchGIpipe.-301-40.\,ooo3,000-12-a.In3inchpipesuitableinthissituation7*hatarethereasons?s.15.Fromthewaterflowcalculatortheheadlossfor3,000metersof3inchGIpipewithaflowof4l/sis46meterTheHGLisplottedonthefigurebelowusingthecalculatedheadloss.a.Ifthe3inchpipefollow6thegroundprofilethenitwilllieabovetheHGLnearthesource*Thismean8thattherecouldbeanegativepressureinthepipelineinthisarea.Thus,threeinchpipeisnotsuiitable.p.16.GiventhegroundprofileinthefigurebelowchooseanappropriatesizeofGIpipeforadesignflowof4l/s.S.16.Usingthewaterflowcalculatorthefollowingvaluesareobtainedforaflowof4l/s.%kancepipediameter(metera)(Inches)headlose(meters)3,ooo4113roc)fJ3463,m2.575Theheadlosefor3inchpipecloselymatchestheavailableheadfromthesourcetothereservoirbutwhentheIlGLisplottedonthefigurebelowitfellsbelowthegroundprofilenearthesource.ThiecanresultinnegativepreeeureinthepipelineAndianotallowable.Thusalargsrdiameterpipemustbeueedinthiearea.However,ifpipelargerthan3inchwereueedfortheentire3,000metersitwouldbelargerthenneededandwasteful.Tochooeeanappropriatesizepipethefollowingvaluesareobtainedfromthewaterflowcalculatorforaflowof4.ljkdistance(meters)pipediameter(inches)headloss(metere),(JOO44i,ooo330,OOf)316I,-2.525If1,000metereof4inchand2,000metersof3inchareusedthetotalheadlossie34meterswhichisI6meterslessthantheavailableheedof50meters.Amoreeconomicalsolutionwouldbetheucleof1,000meterseachof4Inch,3inch,end2.5inchpipe.Thetotalheadlossofthesethreepipesis44meterswhichmorecloselymatchestheavailablehead.TheHGLisplottedonthefigurebelow.Po17.Thefigurebelowcontainsagroundprofilefromawatersourcetoareservoirlocatedatamosque2,ooOmetersfromthesource.!nairvteislocatedl;OOOmetersfromthedouzce..Thtdesignflowforthissectionofpipeis6l/s.PlottheHGLfor4inchpipefromthesourcbtotheairvalveand3inchGIpipefromtheairvalvetothemosque.NowplottheHGLusing3inchp1pipefromthefsourcetotheairvalveand4inchGIfromtheairvalvetothemosque.a.Isthereanydifferencesbetweenthetwoconfigurations?S.17,Fromthewaterflowcalculatorthehead10~sfor1,ooOmetersof4inchGIpipewithaflowof6l/sis8meters.For3inchGIpipeitis33meters.TheHGLsareplottedonthefigurebelow..-15-a.Bothconfiguration8willresultinapproximatelythessmtamountofwaterflowingtothemosque.Ifthe3inchpipeisplacedfirstthenthereisagreateramountofturbulenceandagreaterhead1013satthetrsneitionpointbetweenthe3and4inchpipes.Theflowinthetransitionareafroma4inchtoa3inchpipeissmootherandreemltsinasmallerheadloss.However,forthisparticularsituationtheeffectisnegligible.p.18.Giventheprofileanddesignflowsinthefigurebelowrecommendapprapr%gte’pipesiires...Ua@pipe.luggenttwo,alternative8.s.18.TheHGLandHeadLosoeaarcplottedonthefigurefortwoalternatives.Thus,itisacceptabletouateither2,000meter8of2.5inchpipeor1,000meter6eachof3inchand2inchpipe.TheheadloascsforbothofthO8eareapproximatelythecameandtheflowofwaterwouldalsobeapproxiaaatelythesame~1-17-p.19.Waterforasmallwarungmakanietobeprovidedfromaspringinthemountains.Giventhegroundprr’tileinthefigurebelowrecommendpO86iblOlocationsforbreakpreesuretanks.AssumethatGIpipei8med.a.Whatisthegreateatstaticpressurethatwilloccurinthepipe-linewiththe8Ugge8tbdplactmtntofbreakpressuretank8?b.Willthehigheetstaticpressureeverbeattained?tihatarethereason8?c.WouldtheplacementofthetanksbedifferentforPVCpipe?Whatarethereason?Recommendposeiblelocation8forbreakpreesuretank8ifpralonclassAZpip0i8U8ed.s.19.Thedifferenceinelevationbetweenthe8ourctandthewarungmakan18350meters.Thelowestpointonthepropoeedpipelineis400meterslowerthanthesource.ForOXpipelineswithfittings,themaximumrecommendedheadis50metersandforlineswithoutfittings,200meters.However,thepipelinehasalowpointat400meter8beforerisingagainto350metersatthewarungqakan.Inorderforwatertoflowtothewsrungmakanthelowesttankmustbeabovethe350meterelevationlevel.ItisthereforerecommendedthattheloweettankbeplacedatJGGmeters80that50metersofheadbeavailableforthewatertoflowfromthatpointtothewarungma$un.,‘ithonetankplacedat300metersanothertsnkieneceesaryatanelevationofI50meter880thattherecommendedlimitof200metersisnotexceeded.-18-Suggestedlocation8ofthetwotanksarenotedonthefigurebelow.a.Withthesuggestedplacementoftank8thegreateststaticpressurethatcanbeatt+iaedis150metera.b,!Vhehigheetstaticpressureof150meterswillbeattainedonlyiftheWattrnOWtoeitherOfthetank8isatOppedandthepiperemain8fullofwater.Itiethereforepreferablethatnosalvebeplacedattheinflowtothetank880thatthiseituationdoesnotoccureCaBecau6ethestrengthofPVCisdifferentthan01theplacementofthetankswouldbedifferentandwoulddependontheclassofPVCpipeutilized.PralonclassAZpipehasapressureratingofIOem2/k8whichisapproximatelyequivalentto100metemofbad.Thus,thepipelinepreesureshouldneverexceed100meters.Inthiscasethreetankswouldbenecttmary,plaaedat100,200and300meterelevations.Theselocationsarenotedonthefigureabove.-19-P.20.TheuepartmentofLocalTransmigrationisbuildingasmallkampongwhichwilleventuallyhaveapopulationofYOUpersons.Theyareplanningtobuildasmallgravityfedwatersystemusingaspringabovethekam-pongwithanestimatedminimumflowofI.5l/s.achpersonshouldreceiveatleast80litersperdayofwaterwhichwillbedistributedto6publictapareas.TheFigurebelowisageneralsketchofthevillageandplanneddistributionsystem.P.a.1.Inthissystemastoragereservoirwillbeconstructedatthespring.Recommendanappropriatevolumeforthereservoir?HOWwasthevolumecalculated?Suggestapproximatedimensionsforthere-servoir..?’P.a.2.Thereare6publictapareasfordistributingwater.Rowmanyfaucetsshouldeachtapareahave?p.a3.bqhatisthedesignflowofwaterineachsectionofthedistributionsystem?Howistheflowcalculated?a.Promthereservoirtothecontrolvalveb.FromthecontrolvalvetoTap$’1c.FromTapfi!ItoTap#2d,FromTap#2toTap#3e.FromthecontrolvalvetoTap$4f.FromTapf4toTapf5g.FromTap#5toTapf6P.20.4.%fferencesin‘levationareasfollows:a.SpringtoAirvalve50metersb.Airvalvetocontrolvalve15metersc.ControlvalvetoTap#115metersd.Tap$1toTept25meterse.Tap#2toTap#35metersf.ControlvalvetoTap8415metersg.Tap#4toTap#55metersh.Tapk’5toTap#65metersreanybreakpressuretanksnecessary?Ifso,whataretheirlo-cations?AssumeGIpipeisused.Pa.5.!ihatpipesizesarerecommended?sumethattherearenoproblemswithnegativepressure.UseGIpipe.sa.1.Therecommendedstoragevolumeforstorageatthesourceisbasedontheaveragedailyusageandtheratiooftheestimatedminimumflowtotheaveragedailyflowofthesource.Thissystemwillsupply900personswith80liters/daysotheaveragedailyusageis72m3andtheaveragedailyflowis0.83l/s.Theratiooftheestimatedminimumflowofthesourcetotheaveragedailyflowis1.5i0.83or1.8.bdhentheratioisbetweenoneandtwothentherecommendedstorageisonehalfoftheaveracedailyUseorinthiscase36m3.Theinsidedimensionsofthereservoircouldbeapproximately5meterswideby6meterslongand1.5metersdeep.Theeffectivedepthwouldbeonly1.2metersiftheofftakewereplaced15cmabovethefloorandtheoverflow15cmbelowthecover...?’.-21-S.m.2.!?achtapareaservesapproximately150persons.Withfourfaucetsperareatherewouldbe37.5personsperfaucetandthisisaccept-able.S.20.3.Thedesignflowsarebasedontheaveragedailyflow.jincestorageisabovethepointofusethepipeisinuseonlywhenthefaucetsareopen.Therecommendeddesignflowisthusfourtimestheaveragedailyflowforeachsection.a.Fromthesourcetotk.econtrolvalvetheaveragedailyflowis0.83l/ssotherecommendeddesignflowisfourtimesthisor3.32l/s.Inusingthewaterflowcalculatorthiscanberoundedupto3.4l/s.bande.Atthecontrolvalvethefl