POPULAR CONFIGURATION GCs
Mud-Logger
Theory of Operation
Thesamplegasstream isconnected toabulkheadfittingon thesystem’s thermostattedValveOven
where itflows through thesampling loopof the10portGasSamplingValve,andalso to theCCDdetector.
Thefitting labelled“SampleIn”(picturedatright)on thefrontof theValveOven is thesamplegasstream
inlet. Theusermust regulate thepressureof thesamplestreamso that it enters this inlet at10psi. The
instrument is factorypreset todeliver5mL/min to theCCDat10psi. The
remainderoftheflow,approximately100mL/min, passesthroughtheSample
Loop. Thisrelativelyhighflowrategetsthesamplefromthesamplingpoint
intotheGCwithminimaldelay.
Atanautomaticallyrepeating time intervalcontrolledby the
userwith thebuilt-inPeakSimpledatasystem, theGasSampling
Valve injects thecontentsof itssample loop into theHayesepD
packed column where it is separated into the constituent
hydrocarbon (C
1
-C
6
) peaks and detected by the FID detector.
Betweenautomaticsample injections into thecolumn, the10port
GasSamplingValveisinLOADposition(toprightschematic). In
thisposition,thecarriergasflowsintothecolumnwhilesamplegas
flows through the 25µL Sample Loop and to vent. When
PeakSimpleautomaticallymovesthevalvetotheINJECTposition
(bottomrightschematic), thecarriergasflows though theSample
Loopfirst, thensweeps thesample into theHayesep-Dcolumn.
Once thesampleenters the inlet, itspath is
T’dthroughtworestrictorsandontothedetectors.
Toavoiddamaging theCCD, themaximumpure
hydrocarbon flow to reach thisdetector is5mL/
min. Therestrictors regulate theflow to theCCD
to5mL/minwhenthesampleinletpressureis10psi.
Theremainderofthesamplestream(approximately
100mL/min) flows through the Gas Sampling
Valve’s loopand isperiodically injected into the
Hayesep-Dcolumn, thendetectedby theFID.
10PortGasSamplingValve
