Download Soil Gas Probe User`s Manual

SOILGASPROBE
UserManual
ForDURRIDGEHardenedSteelSoilGasProbe
andAMSStainlessSteelSoilGasProbe
!
WARNING
TheSoilGasProbe,driverodandpilotrodareheavyandlong
piecesofsteel.Theyhavesharp,inducKonhardenedpoints.
Takegreatcareinhandlingthem.Beforeorduringuseplease
makesurethatthepointdoesnotpierceordamageanyperson,
animalorobjectofvalue.
Pleasemakesurethatnogas,electric,telephone,water,sewage
orotherservicelinesoranyobjectsofvaluelieinthepathof
pilotrodorprobebeforedrivingthemintotheground.
2
TableofContents
1 Introduction
4
1.1 Hardened Steel Soil Gas Probe
4
1.2 AMS Stainless Steel Soil Gas Probe
4
2 Soil Gas Probe Placement
5
2.1 Hardened Steel Soil Gas Probe Placement
5
2.2 AMS Stainless Steel Soil Gas Probe Placement
5
3 Connection to the RAD7
6
3.1 Hardened Steel Soil Gas Probe Connection
6
3.2 AMS Stainless Steel Soil Gas Probe Connection
6
3.3 Tubing Connections
7
4 Measurement
8
4.1 GRAB Protocol
8
4.2 Continuous Monitoring
9
4.3 Thoron Protocol
5 Soil Gas Monitoring with DRYSTIK
11
12
5.1 Overview of Soil Gas Monitoring with DRYSTIK
12
5.2 Minimum Flow Rates
14
5.3 Correcting for Very Low Flow Rates
14
5.4 Measuring Thoron in Soil Gas with the DRYSTIK
15
6 Continuous Long-Term Operation
16
7 Care and Maintenance
16
8 Specifications and Components
17
8.1 Soil Gas Probe Specifications Table
17
8.2 AMS Soil Gas Probe Components
17
3
1IntroducKon
Whenmeasuringradonunderground,itisessenKaltocollectsampleswithout
exposingthemtotheoutsideair.DURRIDGEofferstwoheavy-dutySoilGasProbesfor
thispurpose:theHardenedSteelSoilGasProbe,andtheAMSStainlessSteelSoilGas
Probe.
1.1HardenedSteelSoilGasProbe
DesignedtobesimpleandeffecKve,theHardenedSteelSoilGasProbeconsistsofa
hollowsteeltube,½”ODand¼”ID,withacollarandNPTthreadatthetop.A¼”
driverodthatslidesdowntheinsideofthetubehasaheavycupatthetopthat
clearstheNPTthreadandbearsonthecollarroundtheprobe.Alsosuppliedwiththe
probeisapilotsolidsteelrodof⅜”diametertomakeapilotholefortheprobe.
1.2AMSStainlessSteelSoilGasProbe
TheAMSStainlessSteelSoilGasProbeassemblyconsistsofa14”(35.6cm)long
probewithpointedKpanda36”(91.4cm)longextension,bothofwhichcontainrod
inserts.AlsoincludedisaT-handleandabarbedhoseadapter.Therearetwo
couplers,onefortheT-handleandtheotherbetweentheextensionandtheprobe.
Thetworodinsertsalsohaveacouplertojointhemtogether.InaddiKon,awater
shut-offvalveandvacuumgaugeassembly,10b(3.05m)ofplasKctubing,anadapter
to5/16”(0.8cm)ID,andarollofTeflontapeareprovided.
ToassembletheAMSStainlessSteelSoilGasProbe,firstwrapTeflontapearoundthe
threadsofthe14”probeandoneendofthe36”longextension.Jointhetwo
togetherwiththecouplerprovided.EnsurethatthethreadedjointsareairKght.
Couplethetworodinsertstogetherandslidetheminsidetheprobe.AhachtheThandleadaptertotheendoftheprobe,andthenahachtheT-handleitself.
Sec%on1IntroducKon 4
2SoilGasProbePlacement
ToplacetheSoilGasProbe,firstlookforalocaKonwellabovethewatertable,where
thesoilisuniformandgenerallyfreeofrocks.
Cau%on:IfatanypointtheprobeKpstrikesarock,removetherodandchooseanew
locaKonatleastteninches(25cm)fromtheearlierspot.InthissituaKonitisbeher
towithdrawtheprobeandfindanewspotratherthantotrytoforcetheprobepast
therock.
2.1HardenedSteelSoilGasProbePlacement
Hammerthepilotrodintothegroundtothedepthrequiredforsampling.Oncethe
rodhasbeensuccessfullydriventotherequireddepth,removethepilotrodtoleave
apilotholeinthegroundfortheprobetopenetratemoreeasily.
WiththedriverodposiKonedinsidetheprobe,hammerthedriverodandprobe
togetherintotheground,downthepilothole,tothedepthrequired.Thenremove
thedriverod,leavingtheprobeintheground.
2.2AMSStainlessSteelSoilGasProbePlacement
PlacetheKpoftheSoilGasProbeattheinserKonspot.HoldtheprobeverKcallyand
applydownwardpressureontheT-handlewhilerotaKngitslowlyinaclockwise
direcKon.Pleasebecarefulnottobendtheprobe,asthereisnowarrantycoverage
formisuse.
Ifthegroundisfirmitmaybedifficulttoinserttheprobetoasufficientdepth.
DURRIDGEoffersa"slidehammer"thatcanbefihedtotheAMSprobeinsteadofthe
handle.AnopKonalhammerheadhandleisalsoavailable,allowingtheuseofa
malletontheprobe.Eitheraccessoryhelpstopenetrateharderground.Thebest
soluKonhowevermaybetouseapilotrod,madeofregularsteel.Asolidsteelrod,
0.5”(1.5cm)diameterand8”(20cm)longerthantherequiredprobedepthis
opKmal.AskamachineshoptomachineasharpKpatoneendoftherodandifthey
canhardentheKpsomuchthebeher.Twolargeself-gripwrenchescanserveas
handlestopulltherodoutoftheground.
Atthepointwhereyouwishtoinserttheprobe,firsthammerthepilotroddownto
thedesireddepth,thenpullitoutandinserttheprobe.Itshouldgoinwithouttoo
muchdifficulty.Onceinplace,thedepthofinserKonmaybecalculatedbymeasuring
theheightoftheT-handleabovethegroundandsubtracKngthatheightfromthe
overalllengthoftheprobe.
Sec%on2SoilGasProbePlacement
5
3ConnecKontotheRAD7
Topreventfreshairfromleakingdowntheoutsideoftheprobe,thoroughlytamp
downthegroundaroundtheprobe,orbeher,poursomePlasterofParisaroundthe
probeanddownintotheholearoundtheprobe,tosealitin.Leakageoffreshairinto
thesampleacquisiKonpathordowntheoutsideoftheprobetothesamplingpoint
canbeamajorsourceoferrorinthemeasurement.
3.1HardenedSteelSoilGasProbeConnecKon
TherearetwoalternaKvemethodsofconnecKngtheHardenedSteelSoilGasProbe
totheRAD7.Eitherpushtheplug-inhoseconnectorintotheprobe,orscrewonthe
NPThoseconnector.
Withtheplug-inconnectormakesuretheO-ringsarecleanandnotdamagedand
thatitisaKght,pushfitintotheprobe.FortheNPTconnector,KghtlywraptheNPT
threadontheprobewithtwoorthreelayersofteflontape.Applythetapeclockwise
lookingfromabove-thatisinthesamedirecKonastheadapterwhenitisscrewed
on.Screwonthehoseadapter(orthewatershut-offvalve).Makesureitisgoodand
Kght.IfthereisaleakatthisconnecKon,ambientairwillbesuckedintothetubingto
dilutethesoilgas,thusreducingtheradonconcentraKonintheairsampledelivered
totheRAD7.
3.2AMSStainlessSteelSoilGasProbeConnecKon
ToconnecttheAMSStainlessSteelSoilGasProbetotheRAD7,firstremovetheThandleandT-handleadapter.Ifnecessary,apipewrenchmaybeusedtoholdthe
probe.Careshouldbetakentoavoiddamagetothetubeandtothethreads.Remove
therodinserts.WrapTeflontapearoundthethreadontheprobeandscrewonthe
watershut-offvalveandvacuumgaugeassembly.MakesurethejointisKghtand
airKght.Thepipewrenchmaybeusedtoholdtheprobeduringthisprocess.
Sec%on3ConnecKontotheRAD7
6
3.3TubingConnecKons
AhachthesuppliedplasKctubingtothehoseconnector.Theotherendofthetubing
isthenconnectedtothelaboratorydryingunit.(NotethatthisconnecKonshouldgo
totheupstreamconnecKononthedryingunit;thatistheoneclosesttothescrew
cap.)IfaDRYSTIKisused,itshouldbeinsertedbetweentheprobeandthedrying
unit.
Figure1SoilGasProbestandardconfiguraKon
Sec%on3ConnecKontotheRAD7
7
4Measurement
Therearethreemodesofmeasurement.OneisbyobtainingasampleinGRABmode;
anotherbyconKnuousmonitoringusingthestandardprotocol;andthethirdby
operaKngtheRAD7inTHORONmode,withthepumprunningconKnuously.
BeforestarKnganymeasurement,makesuretheRAD7memoryandrunnumberare
notfull.(Press Data, Free [ENTER])andreadthenumberoffreecycles-itshould
bemorethan100,(ThenpressData, Read [ENTER])andseetherunnumberofthe
lastrun-itshouldbelessthan90.Ifthespaceoravailablerunnumbersaretoofew,
downloadthedatafromtheRAD7toacomputerandthenerasetheRAD7memory
(PressData, Erase, Yes [ENTER]).
4.1GRABProtocol
ForGRABprotocol,itisnecessaryfirsttopurgetheRAD7fortenminutesormore
withdry,freshair,beforeconnecKngtheprobe.
WiththeprobedisconnectedbutthedryingunithookeduptotheRAD7startpurging
(Test, Purge, [ENTER]).Aberatleastfiveminutespush[Menu](tostopthe
purge).Withtheprinterswitchedoff,puttheRAD7inSNIFFprotocol(Setup,
Protocol, Sniff [ENTER])andstartareading(Test, Start).Gotothethird
statuswindow(Menu, Enter, Enter, Rt. Arrow, Rt. Arrow)andobservethe
relaKvehumidityinthetoprighthandcorner.LettheRAD7conKnuesniffingunKlthe
relaKvehumiditydropsbelow6%.
IftheRAD7waspreviouslyusedtomeasureahighradonconcentraKon,itwouldbe
prudentalsotomeasurethecountrateinwindowAwhiletheSniffreadingwas
conKnuing.Gotothefibhstatuswindow(fromthethird,justRt. Arrow, Rt.
Arrow).Thelebhandnumberisthecountrate.Typically,0.25cpmwouldbe
equivalenttoaradonconcentraKonof1pCi/L,orabout40Bq/m3.Soilgasisseldom
lessthan100pCi/L,soifthecountrateinwindowAhasdroppedtobelow0.5cpm
andthehumiditytobelow6%,theRAD7isreadytomakethenextGRABprotocol
reading.
Settheprotocolto“Grab”(Setup, Protocol, Grab [ENTER])thenturnoffthe
RAD7.Connectthetubingtotheprobe.Switchontheprinter,switchontheRAD7
andlettheprinterprintoutaheaderforthismeasurement.Checktheheaderto
makesurethesetupiswhatisrequired.GotoTest Startandpush[ENTER]tostart
themeasurement.TheRAD7pumpwillrunforfiveminutes.Theinstrumentwillwait
anotherfiveminutesandthencountforfourfive-minutecycles.Attheendofthehalfhourperiod,theRAD7willprintoutasummaryofthemeasurement,includingan
averageradonconcentraKoninthesoilgasfromthefour5-minutecycle
Sec%on4Measurement
8
measurements.Thismethodgivesaquick(half-hour)readingandusestheleast
amountofsoilgas.TheaccuracywilldependontheradonconcentraKon,andwould
typicallybebeherthan+/-10%.
AberthefiveminutespumpingatthestartoftheGRABprotocol,theRAD7maybe
disconnectedfromtheprobeandeverythingmovedtoanewsiteforthenext
measurementwhiletheRAD7conKnuestoanalyzethegrabsamplejusttaken,which
willsKllbeinthemeasurementchamber.AbercompleKonoftheanalysisitis
necessarytopurgetheRAD7againinpreparaKonforthenextsample.
Ifnecessary,thesoilgassamplecanbepumpedoutofthegroundbyasampling
pump,andfedtoaTedlarsamplebagforlateranalysisbytheRAD7.Withthat
methodology,careshouldbetakentoensurethatthesampleistrulysoilgasfrom
thesamplingpoint,andthatthereisatleast5litresofsoilgassampleinthebag.
Whenanalysisismadelater,withtheRAD7,careshouldbetakenthattheRAD7is
firstpurgedthoroughly,sothattherelaKvehumidityinsidetheinstrumentdrops
below6%.Thenthebagshouldbeconnectedtothedryingunitandagrabsample
protocolmeasurementstarted.Theresultshouldbecorrectedforthedecayofradon
inthesampleduringtheperiodfromacquisiKontoanalysis.
PleasenoteitisimpossibletomeasurethoronconcentraKonwithagrabsample
becauseallthethoronwilldecayawaybeforethemeasurementiscompleted.
4.2ConKnuousMonitoring
ConKnuousmonitoringisasimplemethodofmeasuringthesoilgasradon
concentraKonandprovidesKmeresoluKonintheeventthattheweatheror
barometricpressureischanging.Thesetupisasabove,buttheRAD7presetprotocol
maybesetto[Weeks].ItissKlldesirabletopurgetheRAD7beforestarKngthe
measurement,buttheconKnuousmonitoringprocesswillitselfservetopurgethe
instrumentanddryitout.Inthisprotocol,oncetherelaKvehumiditydropsbelow
10%,theRAD7willpumpforthefirstfiveminutesofeverytwo-hourcycle,andthen
foronlyoneminuteineveryfive.
Therewillbeareadingabereverytwo-hourcycle,thoughthefirstreadingwillbe
slightly(5%)lowbecausethe218-Podecayrateinthedetectortakesmorethan10
minutestoreachequilibriumwiththeradonconcentraKoninthemeasurement
chamber.TherewillbeareadingprintedoutandstoredintheRAD7memoryevery
twohours.Theaccuracyofthereadingswillbe+/-5%forthetypicalhighradon
concentraKonsfoundinsoilgas.
Thismethodwilldrawfromthesamplingpointavolumeofsoilgasequaltotheflow
rateofthepump(L/min)Kmes28minutes,ineverytwo-hourcycle.(Fiveminutesat
thestartandthenoneminuteineveryfivefortherestofthecycle.)Inatypical
Sec%on4Measurement
9
poroussoilthepumpflowratemaybearound0.5L/min.SothesoilgasextracKon
ratewillbearound14litreseverytwohours.Dependingonthesoilporosity,this
wouldcomefromaspherearoundthesamplingpointofaround8"(20cm)radius.
Forthisprotocol,therefore,itisnecessarythatthepenetraKondepthbemuchmore
thanthe20cmradiusofthefirstsamplevolume.Adepthofaround3b(1m)or
more,wouldbesufficientintypicalsoiltopermitconKnuousreadings,at2-hour
cycles,indefinitelywithoutdiluKngthesamplewithambientair,providednoaircan
leakdowntheoutsideoftheprobe.SeeFigures2,3,and4,below.
ThecycleKmecanbechangedasrequired.LongercycleKmeswoulduseless
memoryandtakeslightlylesssoilgasperhouroutoftheground.ShortercycleKmes
wouldgivehigherKmeresoluKonbutrequiredeeperpenetraKontoavoiddiluKon
withambientairfilteringdownthroughthesoiltothesamplingpointinlessthan
threeweeks.
Figure2Soilgasisdrawn
upwards.Thespherical
regionfromwhichthegasis
beingpumpedexpands.
Sec%on4Measurement
Figure3Thesphereshould Figure4UnwantedResult:
notexpandenoughtotouch Sphereradiusexceedsprobe
thesurfaceduringthetest.
depth.Freshairdiffusion
occurs.
10
4.3ThoronProtocol
Thoronprotocoluses5-minutecyclesandprintsoutboththeradonandthoron
concentraKonsattheendofeverycycle.However,thoronhasashorthalf-life(one
minute)sothepumphastorunconKnuously.Forradonthefirsttwocyclesshouldbe
ignoredwhiletheradonreadingreachesequilibrium.Thereaber,therewillbea
readingeveryfiveminutes.Theprintformatshouldbesetto[SHORT]tosavepaper.
Thethoronreadingwillbevalidforallexceptthefirstcycle.
Becauseoftheshortthoronhalflife,someesKmateofsampleacquisiKonKmeis
neededifthethoronreadingsaretobeproperlyinterpreted.DuringacquisiKon,a
flowmetermaybeconnectedtotheRAD7outlet.Thiswillshowhowfasttheairis
flowingfromthesamplingpoint.AnesKmateofthesampleacquisiKonvolumewill
thenallowacalculaKonoftheKmedelaybetweensamplingandmeasuring.Callthe
RAD7onelitre,andthelaboratorydryingunitonelitre.Thesoilgasprobehasa
volumeofaround150mlwhileabout10bof3/16”tubinghasanother50mlfora
totalof200ml.ThetotalacquisiKondelay,then,willbe2.2litresdividedbytheflow
rate.Ifthatis0.5L/min,thedelaywillbe4.4minutes.ThethoronsensiKvitystoredin
theRAD7anKcipatesanacquisiKondelayofabout1.4minutes,sotheextradelayin
thisapplicaKonwillbeabout3minutes.DuringthatKme,thethoronwilldecayto
about0.125ofitsoriginalconcentraKon,sothethoronreadingshouldbemulKplied
by8togivethethoronconcentraKonatthesamplingpoint.
ThefinalvalueofthethoronconcentraKonhaslargeuncertainKesandtheabsolute
accuracyisprobablynobeherthan+100/-50%.ForasoilgasradonconcentraKonof
200pCi/L(8,000Bq/m3)the5-minradonreadingshowever,aberthesecond5minutecycle,willhaveaprecisionof+/-10%(95%confidenceinterval).Higherradon
concentraKonsinthesoilwillimprovetheaccuracyoftheshorttermreadings.
Averagingseveralreadingsoveralongerperiodthanfiveminuteswillalsogivea
moreprecisemeasurement.
Onedisadvantageofthethoronandsniffprotocolsisthatthepumpruns
conKnuously,sothatmuchsoilgasisdrawnfromthesamplingpoint.Comparedwith
‘Weeks’protocol,sniffprotocolwilldrawnearlyfiveKmesasmuchgasperhour.This
meansthatthesphereofgastakenfromthesamplingpointwillbe1.7Kmesthe
radiusofthesamplingspherefor‘Weeks’protocolinthesametotalKme.So,abera
while,ambientairmayfilterdownthroughthesoiltothesamplingpointbeforeits
radoncanreachequilibriumwiththesurroundingradium226.Thismaythusdilute
theradonconcentraKon.Ontheotherhand,thoronhassuchashorthalflife(less
than1minute)thatifthesamplingpointisdeeperthan2b(25cm)thethoroninany
airfilteringdownfromthesurfacewillhavemorethansufficientKmetoreach
equilibriumwiththeradium224inthesoil.So,withasamplingpoint2bormore
belowthesurface,thethoronconcentraKoncanbemonitoredindefinitely,evenas
theradonreadingsstarttodropduetodiluKonwithfreshairfromthesurface.
Sec%on4Measurement
11
5SoilGasMonitoringwithDRYSTIK
5.1OverviewofSoilGasMonitoringwithDRYSTIK
TheDutyCycleControllerbuiltintotheDRYSTIK(exceptfortheADS-1model)is
ideallysuitedforthelong-termmonitoringofradonconcentraKonsinsoilgasusinga
RAD7andsoilgasprobe.TheDutyCycleControllerenablestheaverageflowrateto
bereducedtopreventfreshairfromdiffusingdownthroughthesoiltothesampling
point.WiththeDutyCyclesetappropriately,conKnuousmonitoringofsoilgasfrom
onesamplepointmaybeperformedindefinitely.Themaximumpermissibleflowrate
dependsontheporosityofthesoilandthedepthoftheprobe.
Thehalflifeofradonis3.8days.Theairsamplemaybeconsideredtobedrawnfrom
aspherecenteredonthesamplingpoint(seeFigures2,3,and4inSecKon4.2).Ifthe
spheretakestwoweekstogrowbeforeitjusttouchesthegroundsurface,thenit
takestwoweeksforairtofilterdowntothesamplingpoint.Wemaythenacceptthat
theairatthesamplingpointconKnuestostayveryclosetoequilibriumwiththe
radiuminthesoil.
Figure5SoilGasProbeconfiguraKonwithDRYSTIK
Sec%on5SoilGasMonitoringWithDRYSTIK
12
ForaprobedepthofDcm,themaximumspherevolumewillbe4πD3/3,000litres.If
theporosityofthesoilis50%,thecorrespondingairvolumewillbe2πD3/3,000.Two
weeksisabout20,000minutes.Sotheaverageflowratemustbelessthan2πD3/
60,000,000litre/min.Ifweallowthat2πiscloseto6,theratemustbelessthanD3*
10-7litre/minwhereDistheprobedepthincm.
Maximumflowrate,F,isroughlygivenby:
F=D3/107litre/min
whereDistheprobedepthincm.
If,forexample,Disabouttwofeet,or61cm,themaximumflowratetomeetthis
criterionforconKnuoussamplingwillbe0.022L/min.UncertainKesintheporosity
andotherassumpKonsmaymakeitadvisable,forthisdepth,tokeeptheflowrate
lessthan0.01L/min.
Typically,theONflowrateoftheDRYSTIKissettoabout0.2L/mintomatchthe
averageflowrateofaRAD7wherethepump,pumpingat1L/min,runsforone
minuteineveryfive.OntheDRYSTIKADS-3orADS-3Rsimplyselectthedesired‘Soil
Gas’profile.OntheDRYSTIKADS-2,theDutyCycleshouldbesettoabout5%,orto
anONKmeof60secondsandanOFFKmeof1200seconds.Thisproducesan
averageflowrateof0.01L/minfromthesoilgasprobe.
Withaprobedepthof61cmandaporosityof50%,thisse{ngwillenable
conKnuous,indefinitesamplingofthesoilgasforradonconcentraKonwithout
significantdiluKonofthesamplebyfreshairdiffusingdownfromthesurface.
Increasingthedepthby26%,to77cm,willallowdoubletheflowrate,assuming
uniformsoilporositydownto2morso.
Sec%on5SoilGasMonitoringWithDRYSTIK
13
5.2MinimumFlowRates
Radonhasahalflifeof3.8days.Iftheairsampletakesmorethananhourortwoto
reachthemeasurementchamber,theremaybeenoughsamplelosstocallfora
sampledecaycorrecKon.Withalaboratorydryingunitintheairpath,youcan
assumeasamplepathvolumeofabout2litres,plusmoreiftheprobeissofarfrom
theRAD7thatthevolumeofthetubingbecomessignificant.Iftheprobeiscloseto
theRAD7(withinabout10m)andthemaximumacceptabledelaybeforecorrecKons
havetobeappliedis2hours,thentheminimumpermissibleflowratewillbe2L/
120min,or0.016L/min.FlowrateslowerthanthiswillrequireacorrecKonfactorfor
radondecay,asdiscussedbelow.
5.3CorrecKngforVeryLowFlowRates
Intheexamplesabove,itmaybeseenthatforaprobedepthof61cm,toavoid
diluKonoftheairsampleaberaweekortwoofsampling,aflowrateofnomore
than0.01L/minisdesired,butwiththisflowratethesamplewilllosesomeradonby
radioacKvedecayduringsampleacquisiKon.
OnesoluKontothisproblemwouldbetoincreasethesamplingdepthto2b6inches
(77cm)ormoreanddrawatanaverageflowrateof0.02L/min.Thismaybe
obtainedwithadutycycleof10%(forexample,anONKmeof3sec.andanOFFKme
of30sec.)withaflowrateof0.2L/min.
AnothersoluKonwouldbetoleavethesamplingpointat2b(61cm),drawatan
averageflowrateof0.02L/min,takingnoteofanylong-termchangeintheaverage
aberoneweekofsampling,andthenapplyacorrecKonforfreshairinfiltraKonto
readingsaberthreeorfourweeksofsampling.
AthirdsoluKonwouldbetokeeptheprobeat2b(61cm)andkeeptheflowrateat
0.01L/min.Assumingasamplevolumeof2L,thiswillcauseanacquisiKonKmeof
around2/0.01min=200minutes.In200minutes,about2.5%oftheradonwillhave
beenlostbyradioacKvedecay.Afactorof1.025maythereforebeappliedtothe
readingtocorrectfortheloss.
Sec%on5SoilGasMonitoringWithDRYSTIK
14
5.4MeasuringThoroninSoilGaswiththeDRYSTIK
Thoronhasahalflifeoflessthanaminute.UsingtheDRYSTIKwithatypical
configuraKonwillinevitablycausesampleacquisiKondelaysfarinexcessofone
minute.Thereforechangesareneededforthemeasurementofthoron.
Tomeasurethoroninsoilgas,theDRYSTIK’sneedlevalveshouldbebypassedandthe
pumpshouldbesettorunconKnuously.Theflowratewillthenbecloseto1L/minif
thesoilisporous.
Ataflowrateof1L/min,withaLaboratoryDryingUnitinthesamplepath,the
sampledelayincreaseoverstandardthoronprotocolwillbeabout1minute.
ThereforethethoronreadingsshouldbemulKpliedbyafactorof2.Iftheflowrateis
reducedand/orthesamplevolumeislarger,agreatercorrecKonfactorwillbe
needed.
Sec%on5SoilGasMonitoringWithDRYSTIK
15
6ConKnuousLong-TermOperaKon
IthasbeenproposedthatconKnuousmonitoringofsoilgasforradonmaybeauseful
techniqueforpredicKngearthquakes.Forthispurpose,anarrayofsoilgasprobes
coveringhalfasquarekilometer,say,maybemoreinformaKvethanasinglesampling
point.SuchanarraycanbemonitoredwithasingleRAD7.FineboreplasKctubes
mayberunforhundredsofmetersfromeachprobetoacentrallylocatedDURRIDGE
valvemanifoldsystem.TheRAD7maybeconnectedtothemanifoldandswitched
fromonetubetoanotherunderthecontrolofthemanifoldsystemmicro-controller.
EachtubeispurgedpriortotheRAD7hook-up,sothatthesoilgassampledisfresh.
Onemeasurementcanbemadeeveryhour.Ifeachsamplingpointhadtobereadsix
Kmesaday,say,therecouldbefoursamplingpointsmonitoredbyoneRAD7.
WithaBluetoothadaptorconnectedtotheRAD7,thecontrollingPCcanbelocated
anywhere.Real-KmedataiscollectedbythePCwhileaback-upsetofdataisstored
intheRAD7.PleaseseetheRAD7andCAPTUREsobwaremanualsforfurtherdetails.
7CareandMaintenance
Toensurethelongevityofthesoilgasprobe,avoidhi{ngrockswithexcessiveforce.
Removealldirtandcontaminantsfromtheprobeabereachuseandstoretheprobe
componentsinadryplace.Keepingtheprobeproperlyoiledwillhelptopreventrust
fromforming.
ContactDURRIDGECompany,[email protected],fortechnicalassistance.
Sec%on6ConKnuousLong-TermOperaKon
16
8SpecificaKonsandComponents
8.1SoilGasProbeSpecificaKonsTable
DURRIDGEHardenedSteel
SoilGasProbe
AMSStainlessSteel
SoilGasProbe
ConstrucKon
Steel
StainlessSteel
PilotRod
Included
NotIncluded
VacuumGauge
OpKonal
Included
InserKonMethod
Hammerintoground
Pushintoground
(hammeropKonal)
RemovalMethod
Self-gripwrenches(notincluded) Pulloutusingincludedhandle
HoseConnectors
FemaleNPTthreadandO-ring
Femalehoseconnector
Maintenance
Cleanandoilaberuse
Basiccleaningrecommended
AddiKonalNotes
—
Metaljointsmaybetapedto
preventoutsideairfromentering
8.2AMSSoilGasProbeComponents
Sec%on8SpecificaKonsandComponents
17
18
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