(StandardTCDdetector block access continued)
4. Cut thefiberglass tapewrappedaround thedetectorblockandpeel itoff. Unwrapandremove the
heater rope from thedetector block (it isprobablyaffixed to the thermocouplewireswithmore
fiberglass tape).
5. Disconnect the thermocoupleby loosening thesmallphilipsheadscrewwhichholds iton the
detectorblockclamshell. Next,removetheclamshellbyunscrewingthetwosmallphilipsheadscrews
thathold itshalves together. Gentlyremove thewhite insulation toreveal thedetectorblock.
6. TheTCDfilamentsaresecured in thedetectorblockby twoplates,eachofwhich isheld inplace
with threehexagonalheadscrews. Holding thedetectorblockwithonehand,useanAllenwrench to
unscrewandremove thehexagonalheadscrewsfromoneof thefilamentsecuringplates.Then,slide
thefilamentsecuringplateoff thefilamentsand leads. Set itsecurelyaside.
7. Once thesecuringplate isremoved, thefilamentandrubberO-ring thatseals itcanbegentlypulled
outof thedetectorblockcell. Whenreplacingafilament, itsrubberO-ringshouldalsobereplaced.
Check the lipof thedetectorblockcellforfragmentsof theoldO-ringand ifanyarepresent, remove
themas theywill interferewithpropersealingof thecell. Ifyou’rereplacingonereferenceorsample
filament, replace theotherat thesame time. Ifyoudidn’thavefundisassembling theTCDdetector
block, replaceall the filamentswhileyouhave itopen. It’sagood idea to remove then replaceone
plate and corresponding pair of
filamentsatatimetoavoidmixingup
theirconnections.
8. To install anew filament,
color-
code
it thesameas the filamentyou
arereplacing, thenslide it, leadsfirst,
through the appropriate hole in the
filamentsecuringplate. Anexistingor
replacement filamentshouldoccupy
the other hole. Place a new rubber
O-ringagainst therimof thedetector
blockcellwhichwillaccept thenew
filament. Placefilamentsecuringplate
andfilamentsagainstthedetectorblock
with thefilaments inside thedetector
blockcells. Replaceand tighten the3
hex-headscrews. Repeatthisprocess
on other side to replace the
correspondingfilament.
9. Reverse your steps for TCD
detector reassembly. Steps 7-10of
thehigh temperatureTCDdetector
block access instructions detail
reassemblyoftheinnerclamshelland
outerdetectorhousing.
Filament securingplate
Filament
Samplecell
Referencecell
Detectorblock
RubberO-rings
Hexagonalhead
screws
Insulated filament leads
Exploded viewof the standardTCDdetector block
Replacing the TCD Filaments continued
DETECTORS
Thermal Conductivity Detector - TCD
