Replacing the TCD Filaments continued
B. High temperatureTCDdetectorblockaccess
Thehigh temperatureTCDassembly is the sameas the standard: outerhousingaroundan inner
clamshellcase. Thehigh tempdetectorblockusesglandnutsandcoppergaskets tosecure thefour
filaments in its twocells. Insteadof theheaterrope, itemploysaheatingcartridge,which is inside the
innerclamshellcasewith thedetectorblock.
1.Withasmallbladescrewdriver,disconnectthefilamentleadsfromthebridgeterminalbyloosening
thesetscrews.
2. Remove thedetectorhousingbyunscrewing the thumbscrew thensliding thehousingcoveroff
toward the right-handedgeof theGC. Gently remove thewhite insulation to reveal thedetector
block.
3. Disconnect thedetectorblockgas inletsandoutlets. Thereferencegas inlet isdisconnectedat the
polishingfilter immediatelybehind thecolumnoven. Thereferencegasoutlet isdisconnected inside
thecolumnoven. Disconnect thesamplegas inletat the fittingon thecolumn. Thedetectorblock
samplegas inlet tubinghasacoppersheathfor identification. Thesamplegasoutlet isusuallyrouted
out the right sideof thecolumnoven. Once these three fittingsare loosenedand thedetectorblock
tubingfreed,gentlypull thedetectorblockawayfrom thehousing.
DETECTORS
Thermal Conductivity Detector - TCD
Explodedviewofhigh temperatureTCDdetectorblockand innerclamshell
Coppergaskets
Glandnuts
Filaments
and leads
Detectorblock
Installed/secured filaments
Halfof innerclamshell case
Halfof innerclamshell case
Insulated
padding
Insulated
padding
