Valco Instruments Co. Inc. TCD User manual

Valco Instruments Co. Inc.
tcd2.p65
Rev 4/12
Printed in USA
Microvolume Thermal
Conductivity Detector
Instruction Manual
Valco Instruments Co. Inc.
800 · 367 · 8424 sales
713 · 688 · 9345 tech
713 · 688 · 8106 fax
[email protected]
VICI AG International
Schenkon, Switzerland
Int + 41 · 41 · 925 · 6200 phone
Int + 41 · 41 · 925 · 6201 fax
[email protected]
North America, South America, and Australia/Oceania contact: Europe, Asia, and Africa contact:

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Table of Contents
Introduction
Descriptionand OperatingPrinciple ............................................................... 1
SafetyNotesand Information ........................................................................ 2
Components of the Detector System ............................................................. 3
Descriptionof Controls andConnectors ......................................................... 4
SystemRequirements
Components Not Included with the Detector System ..................................... 7
System Purity................................................................................................ 7
RecommendedCarrier GasPurifiers .............................................................. 7
CarrierGas Selection..................................................................................... 7
GCColumn Selection..................................................................................... 8
Installation
GeneralPrecautions ...................................................................................... 9
MountingtheDetector on theGC ................................................................... 9
GasConnections ..........................................................................................10
ColumnConnection.......................................................................................12
ElectricalConnections ..................................................................................13
InitialPower-Up .............................................................................................15
Troubleshooting
TroubleshootingChart ...................................................................................17
HeaterFaultDetermination............................................................................17
DetectorFaultDetermination.........................................................................18
Maintenance
BakeOut Procedure .....................................................................................19
Disassemblyand Cleaning............................................................................19
Warranty .............................................................................................................20
DetectorPerformanceLog ...................................................................................21

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1
Introduction
DescriptionandOperatingPrinciple
TheThermalConductivity Detector (TCD)hasbeen oneofthe most popular
GC detectors since the 1950’s, second perhaps only to the Flame Ionization
Detector (FID). The principal of operation is based on the relative change in
the thermal conductivity of the gas passing across the detector filament as
components elute from the column. Heat is lost continuously by the filament
through the carrier gas to the cell wall of the detector. By measuring the
amountofcurrent required tomaintaina constant filament temperatureas
gases of varying thermal conductivities cross the filament, a chromato-
graphic signal is produced. This process is nondestructive of the sample and
isconcentration dependent.
TheValco MicrovolumeTCD is unique in its implementation. Since changes
in conductivity are measured only by the change in current required to keep
the filament at a constant temperature, each of the two filaments can be
operatedindependently without referencingthese changestoa matched
filament with reference gas. This constant temperature provides longer
filament life and safeguards it from the extremely high temperatures and
oxidation which can occur with high concentrations of oxidative or corrosive
components. Optionalsignal referencing isprovidedto minimizebackground
variablessuch as columnbleed andtemperatureprogramming.
Figure 1: Unique dual filamentdesign
Cell volume has been minimized to accommodate capillary column
chromatography and optimize the sensitivity of the detector at low flow
rates. (Carrier flow rates of 1 - 10 mL/min are recommended for best sensi-
tivity.) Thermal stability is maintained in the detector cell to within 0.010°C
drift, giving the detector a stable, noise-free signal.
The ModelTCD2 is a stand-alone system which can be easily added to
any chromatograph. It consists of a detector and a control module which
incorporates the electrometer andtemperaturecontrols. Thedetector cell
includestwo separate filaments,capableof independentorreferenced
(differential)operation. Outputsignal is providedas0-1 and 0-10 volt
attenuatedforchartrecordersand 0-1 and 0-10voltsunattenuatedfor
integrators and data systems.
FILAMENT
AFILAMENT B
A
FLOW
INLET
B
FLOW
INLET
OUTLET OUTLET

2
Safety Notes and Information
Symbols HOTSURFACE
The surface of the detector body may be hot while in
operation (possibly in excess of 250°C). Observe caution.
ATTENTION
Refertothe manual.
PROTECTIVE EARTH
Thisinternalconnection provides protectionagainst electric
shock from mains voltages and should not be removed.
InstallationCategory
Thisequipment has beendesigned for installationcategory (overvoltage
category) II, pollution degree 2. It has been approved for use only in heavy
industrial environments and may not be used in the residential, commercial,
orlight-industrial environment.
Safety
This instrument has been designed and tested in accordance with the
product safety standard, EN61010. It has left the factory in a safe
condition. This instruction manual contains important information and
warnings which must be followed by the user to insure safe operation and to
retain the instrument in a safe condition. The case, chassis, and measuring
terminals are connected to the protective earth contact of the mains inlet.
Theinstrument operates witha three-conductor powercord having apro-
tective earthing conductor and a plug with an earthing contact. The mains
(line) plug shall only be inserted in a socket outlet provided with a protective
earth contact. The protective action must not be negated by the use of an
extension cord without a protective conductor. Use only with an approved
mains supply cord having a rating of 2A, 250V, or greater. Do not use this
equipmentina mannernotspecified herein.
Maintenance
The exterior of the instrument should be cleaned regularly with a dusting
brush.If necessary, the casing can be cleaned with a moistened cloth
(99% water + 1% mild detergent). Spirit or petroleum ether can be used
to remove greasy dirt. Any other cleaning agents can attack the plastic
andpainted surfaces.
Under no circumstances should the cleaning fluid get into the instrument.
Petroleum ether is flammable, and care should be taken in its use.
The detector must be returned to the factory when filament replacement is
required. CallVICITech Support for return authorization.
Introduction

3
Components of the Detector Systems
Components of the detector system are listed in Tables 1 and 2. Check the
contents of the packages to verify that everything is present. Contact the
factory if anything is missing or damaged. (NOTE: damaged shipments
must remain with the original packaging for freight company inspection.)
Introduction
Description Quantity Product number
Detector cell, Nickel-Iron filament 1 TCD2-NIFED
Controller unit with power cord 1 TCD2-C
Includes: Cable, output 2 I-24010
1/16' zero dead volume union 2 ZU1C
Fused silica adapter for 0.53 mm ID x 0.8 mm OD capillary column 2 FS1R.8
1/16" zero dead volume nut 2 ZN1
1/16" zero dead volume ferrule 2 ZF1
Table 1: Components of the TCD2-NIFE system
Description Quantity Product number
Detector cell, Tungsten-Rhenium filament 1 TCD2-WRE
Controller unit with power cord 1 TCD2-C
Includes: Cable, output 2 I-24010
1/16' zero dead volume union 2 ZU1C
Fused silica adapter for 0.53 mm ID x 0.8 mm OD capillary column 2 FS1R.8
1/16" zero dead volume nut 2 ZN1
1/16" zero dead volume ferrule 2 ZF1
Table 2: Components of the TCD2-WRE system
Specifications
Mains(line): 115/230V~50/60 Hz,175VA
Fuse: 2 A, time-delay, 5 x 20 mm
Pressure: 6.9 kPa (1 psi) operating, 6.9 MPa (1000 psi) max.
working
Maximumtemperature 300°C
Heaterpower: 60 W max., 48V, PWM
Outputimpedance: 100 Ω

4
Description of Controls and Connectors
Controls and connectors are indicated in Figures 2 and 4.
MAINS switch(rear panel)
Controls mains (line) voltage to the controller unit. When this switch is
on ( | ), the unit is operational except for the detector filaments (see next
paragraph)and thedetectorheater willoperate ifconnected.
FILAMENT switchandindicator
Controls power to the detector filaments; when the switch is on, current
passes through the filaments. The indicator will light even if the detector
is not connected to the controller.
DETECTORTEMPERATURE control andindicator
Sets the temperature (°C) of the detector heater block. The indicator is
steadily on when maximum power is being applied to the heater, steadily
off when no power is applied, and regularly blinking on/off when the set
temperaturehas beenestablished.
Note that due to the fail-safe mechanism designed into the temperature
controller, the heater will not operate if mains power is applied before the
heater is connected or if the detector is too cold (< 0°C). If the heater is
disconnected with mains on, the unit must first be turned off to restore
control of the heater; if the unit is operated in a very cold environment,
thedetectorshould first begently warmed without powerapplied.
The fail-safe mechanism will also act under any condition resulting from loss
ofcontrol( e.g. ,over-heating,RTD failure, etc.). Ifproperprocedures have
been followed and the controller will not heat the detector, there is cause
to suspect that the fail-safe mechanism has been activated. Consult the
factoryoran authorized representative. Notethat the maximum temperature
for operationof theTCD2is 300°C.
FILAMENTTEMPERATURE switch
Separate 10-turn knobs control Filaments A and B.The value displayed
corresponds to temperatures indicated in Figure 3 for nickel/iron filaments.
COARSE ZERO control
Oncefilamenttemperature hasbeenapplied, the CoarseZero knob makes
coarse adjustments of the zeroing voltage supplied for establishing the
baseline zero on both the strip chart output and the integrator outputs.
FINE ZERO control
Once coarse adjustments have been made, the Fine Zero control is used to
make fine adjustments in the output signals.
ATTENUATION control
The Attenuation control determines the attenuation of the signal for the chart
output.
RECORDERswitch
The Recorder switch selects which signal is directed to the chart output.
The choices are A, B, or A - B (or A minus B, which is conventional
differentialoperation with theB channel representingthe reference.)
The selected output signal is displayed in the LCD display.
Introduction

5
Introduction
Figure 2: Front panel controls
Figure 3: Actual filament temperature vs. filament temperature knob settings
ACTUAL TEMPERATURE IN °C
FILAMENT TEMPERATURE KNOB SETTING
012345678910
0
50
100
150
200
250
300
350
400

6
MAINS POWER connector
For connection to 115/230VAC source.
CHART OUTPUT connector
Normally connected to a strip chart recorder. This output has an attenuated
range of 0-1 volt and 0 - 10 volts, with the signal scaled by the attenuation
factor set on the front panel. The output also has an internal signal reference
(-) at zero volts. For best noise performance, the shield (earth) and signal
reference(-)should notbeconnected together.
UNATTENUATEDOUTPUT connector
Normally connected to a data acquisition system or other recording means.
For convenience, full-scale 0 - 1V and 0 - 10V outputs are provided, with an
internal signal reference (-) at zero volts. For best noise performance, the
shield(earth)andsignal reference(-)shouldnot beconnected together.
DETECTORconnector
For connection to the detector control and heating system.
NOTE:These terminals are for connection only to
equipment having no accessible live parts.
Introduction
Figure 4:Rear panelconnectors
CHART AB A-B
OUTPUTS
DETECTOR
SERIAL NO.MODEL NO.
Valco Instruments Co. Inc.
MAINS SWITCHMAINS POWER
CONNECTOR
DETECTOR
CONNECTOR
CHART OUTPUT
CONNECTOR
UNATTENUATED
OUTPUT
CONNECTORS
MODEL TCD2-C
115/230 175VA MAX.
T2.0A
250V
MAINS
Valco Instruments Co. Inc.
Made in USA by

7
System Requirements
Components Not Included with the Detector System
•Carriergas (99.999%purityis recommended)
•Ultra highpuritygrade gas pressure regulator withstainless steel
diaphragm(recommended)
•Any specialadapters required forconnectionto the gasregulator
•Flowmeasuring device
•Flowregulating device
System Purity
Since detection of low concentrations depends in part on the purity of the
carrier, the purest carrier available must be used in order to achieve the
lowest possible detection limit.To maintain carrier purity, extra care must be
taken to assure that the delivery system is clean and free of leaks. Use
stainless steel tubing (cleaned to removed manufacturing solvents) instead
of nylon orPTFE tubing, which can diffuse contaminants into the carrier.
RecommendedCarrierGasPurifiers
TheValcoHeliumPurifer (productnumberHP2)andNitrogen Purifer(product
number NP2), which utilize a rare earth gettering alloy to effectively remove
contaminants,arerecommended forppmlevel analysis ofpermanent gases.
For other applications, economical and convenientVICI Mat/Sen purifiers are
appropriate. Orderthe P300-1 fornitrogen, P200-1forhydrogen, orthe
P100-1forhelium and otherinert carrier gases.
CarrierGasSelection
The detector’s response to a component is based upon the difference
between the thermal conductivities of the component and the carrier gas: the
greater the difference, the greater the response.The table below shows
thermal conductivities for a variety of light gases.
Hydrogen 45.9
Helium 36.9
Neon 11.8
Methane 8.6
Oxygen 6.6
Air 6.4
Nitrogen 6.4
Carbonmonoxide 6.2
Water 4.5
Argon 4.5
Carbondioxide 4.2
As an example, note in the table that the thermal conductivity of hydrogen is
46 and helium is 37, while nitrogen is only 6 and argon is even lower at 4.
Since the largest difference in thermal conductivity yields the best response,
detection of small amounts of hydrogen is better done with argon or nitrogen
carrierthan with helium.

8
2
13
⁄ 16 "
5
5
⁄ 8 "
1
1
⁄ 4 "
3"
6"
1
1
⁄ 2 "
1"
Figure 5: Detectorassembly mountingdimensions
However, while nitrogen as a carrier yields excellent response to hydrogen,
the response to oxygen and carbon dioxide is diminished compared to the
levels that could be achieved with helium or hydrogen. Argon would yield
poorresponseto carbon dioxideandwater,butwould beadequateforother
components.
There is no absolute “best choice” of carrier gas. For any situation, the choice
must take into account all of the parameters involved: column
characteristics, components of interest and their concentrations, safety
considerations, carrier cost, etc.
GC Column Selection
Cellvolume has beenminimized to accommodatecapillary,megabore,and
micropacked columns, and to optimize the sensitivity of the detector at low
flow rates. However, standard packed columns may also be used if sensitiv-
ity is not an issue.
System Requirements

9
CHANNEL
A
VENT
CHANNEL
B
VENT
CHANNEL
A
INLET
(gold ferrule)
CHANNEL
B
INLET
(stainless ferrule)
Installation
The detector is usually mounted on top of the GC column oven. The power
cord for the controller is 1.8 m (6') long; the detector cable and the signal
outputcables (attenuated andunattenuated) are 1.2m (4') long.
General Precautions
•Do not turn the unit on until the carrier gas is flowing through the detector.
•Do not shut off or disconnect the carrier gas when the detector is hot,
even if the unit is turned off. Turn off the power switch on the back of the
controllerandallow thedetectorto cool downnaturally before disconnect-
ing or shutting off the carrier gas.
•Position the controller unit where the mains switch on the rear panel can
bereachedeasily.
Mounting the Detector on the GC
VerticalMounting
Thedetector has noparticular orientation
requirements,but it shouldhave adequate
thermal isolation from the column oven and
injection port. Most GCs have an existing
opening which will allow theTCD2 to sit
vertically on top of the column oven with the
column inlet extending into the oven. If you
are replacing an existing detector, you can
usually just remove it and set the TCD2 in its
place. If not, use a drill or chassis punch to
drill a hole of the proper size, and set the
detectorin position.
While trying to match base plate mounting holes to every GC on the market
is impractical, we have located the mounting holes so that at least two of
them will coincide with existing holes on the GC. (Refer to Figure 5.)
Orient the detector to allow for easy cable and gas connections. The inlet
lines installed into the detector must enter the column oven and permit
columnconnection. Temperature loss betweenthe column outletandthe
detector should be minimized to prevent possible condensation of the
sample.
CAUTION: Do not mount the detector near the column
oven cool-down vents.
Horizontal Mounting
Some older GCs have access to the column oven through the side of the
GC.This does not present a problem as far as operation of theTCD2 is
concerned. Drill a hole at the appropriate location, orient the detector for
convenient connection, and mark the position of the mounting holes. Drill the
mounting holes and secure the detector to the side of the GC with four sheet
metalscrews(not supplied).
Figure 6: Detector connections

10
Gas Connections
Remember these three points discussed earlier: (1) all surfaces that contact
the gas stream must be glass or stainless steel; (2) do not use copper tubing
or brass fittings; and (3) all tubes must be thoroughly cleaned and baked
before use. The installation instructions below assume that the detector
carrier will be supplied from a nearby cylinder. If your installation is different,
you may need to modify the instructions appropriately. Consult theVICI
catalog or vici.com for any fittings and tubing required.
The figures below illustrates gas connections for a typicalTCD2 detector
system, in referenced and unreferenced modes. Since the distance from the
carrier supply to the GC varies from installation to installation, we do not
supply tubing to go from that point to the GC.
Installation
GAS CHROMATOGRAPH
COLUMN INJECTOR
TEE
(ZT1)
PURIFIER
CARRIER GAS
(99.999% purity)
FLOW
CONTROLLERS
DETECTOR
CHANNEL A
INLET
(gold ferrule)
CHANNEL B
INLET
(stainless ferrule)
CHANNEL
A
VENT
CHANNEL
B
VENT
Figure 7: Referenced mode (A - B)
Figure 8: Unreferencedmode
GAS CHROMATOGRAPH
COLUMN INJECTOR
TEE
(ZT1)
PURIFIER
CARRIER GAS
(99.999% purity)
FLOW
CONTROLLERS
DETECTOR
CHANNEL A
INLET
(gold ferrule)
CHANNEL B
INLET
(stainless ferrule)
CHANNEL
A
VENT
CHANNEL
B
VENT
COLUMN INJECTOR

11
InstallingandPurgingtheGasRegulator
1. Make sure the on/off valve on the helium cylinder is completely closed.
Screw the CGA fitting nut of the regulator into the helium cylinder. Go
beyond finger-tight, but do not tighten the nut all the way – some leakage
isrequired forthepurging operation.
2. Turn theoutput pressure regulatingknob completely counterclockwise.
3. Open the cylinder on/off valve slightly and quickly close it again.
4. Adjust the tightness of the regulator connecting nut to allow a pressure
reduction of ~690 kPa/sec (100 psi/sec). With a new bottle, the gauge
should start out at about 14 MPa (2000 psi).
5. When the pressure drops into the 1.4 - 3.4 MPa (200 - 500 psi) range,
open the cylinder on/off valve slightly and quickly close it again.
6. Repeat Step 5 eight or ten times to be certain that all the air is purged.
On the final purge, tighten the regulator connecting nut very securely as
the pressure approaches the 2.1 - 3.4 MPa (300 - 500 psi) range.
7. Open the cylinder valve to pressurize the regulator once again, then close
it and observe the high pressure gauge needle for 15 minutes. If it doesn’t
move, there is no critical leak on the high pressure side of the regulator.
CAUTION: Never use leak detecting fluids on any part of
this system.
Installation
InstallingandPurgingaPurifier
1. If the pressure regulator has a 1/8" male cone-type outlet port, install
theValco 1/8" external to 1/16" internal reducer (EZR21);if it has a 1/4"
male cone-type outlet port, install theValco 1/4" external to 1/16" internal
reducer (EZR41). For other regulator outlet fittings, a wide variety ofValco
adaptersare available.
2. Remove the cap from the inlet tube of theValco helium purifier and insert
the tube fitting into the 1/16" reducer port.(Keep the outlet tube capped.)
Use a 1/4" wrench to turn the nut one-quarter turn past the point where the
ferrule first starts to grab the tubing. Do not remove the fitting. When
made up properly, it should be leak-tight.
3. Turn the outputpressure regulating knobclockwise untilthe gauge
registers 345 KPA (50 psi).
4. Allow five minutes for equilibration, then turn the regulating knob all the
waycounterclockwise.
5. Observe the needle of the output pressure gauge for 15 minutes. There
will be a slight initial drop, but if it doesn’t move after that, consider that
all the connections are tight.
6. If necessary, use an electronic leak detector to locate any leaks. If a
leak detector is not available, tighten all the fittings (including the output
pressureguage),and repressurize the systemforanother test.
7. Upcap the outlet tube of the purifier and purge the system for 15 to 30
minutes at 60 - 80 mL/min to eliminate air from the purifier getter material.
EZR21

12
Installation
ColumnConnection
To prevent detector contamination,we strongly recom-
mend disconnecting the column from the detector during
column bakeout procedures.
Referencedmode
In the referenced mode, the column is connected to the Channel A inlet, and
the carrier gas stream is split and used as a reference in channel B. The gas
flow rate from both channels must be the same (flow balanced). This mode
of operation provides the best baseline stability and the least background
noise.
Unreferencedmode
In the unreferenced mode, Channels A and B are used independently. One
column connects to the Channel A inlet, and the other to Channel B. The
carrier gas must be the same for both channels.
It is also possible to use only one channel with the other capped off, as long
as the filament temperature control knob of the unused channel is set to
zero.
The unreferenced mode has certain limitations:there is a possibility of
detectorcross-talk(interference) ifcompoundconcentrations exceed 1%,
andbaseline drift andbackground noise aregreater than withthe referenced
mode.
To make column connection as convenient as possible, eachTCD is
shippedwithtwoValco 1/16" unions(ProductNo.ZU1C)completewith
nuts and ferrules (Product Nos. ZN1 and ZF1). Also included are two fused
silica adapters (FSR1.8) for use with .53 mm ID wide bore capillary columns
(.8 mm OD). Refer to the information below to determine the correctValco
fitting for use with other columns.
ColumnConnectionFittings
Packed Columns
A 1/16" packed column requires only the ZU1C which comes with theTCD.
For 1/8"columns, order aZRU21.
ZU1C
Used with 1/16" column
ZRU21
Used with 1/8" column

13
Installation
EZU1
Used with 1/16" column
EZRU21
Used with 1/8" column
ZU1C with fused silica adapter
Column size
.32 mm ID x .5 mm OD
.25 mm ID x .4 mm OD
< .2 mm ID
Adapter required
FS1R.5
FS1R.4
FS1R.2
Packed Columns with Swagelok®-type Female Nut
The connection of these columns is similar to that for standard packed
columns, but requires a union which adapts the female nut to theValco
fitting.
Capillary Columns
Connection of these columns requires the use of the ZU1C with the appro-
priate fused silica adapter. For a .53 mm ID x .8 mm OD column, use the
FSR1.8 supplied with theTCD. For other sizes, use this table to determine
theproper adapter:
TestingforLeaks
It is critical for the system to be leak-tight, and an additional check at this
point can save many headaches later on. To test for leaks:
1. Insure that both outlets are capped.
2. Pressurize the entire system with helium to 138 kPa (20 psi).
3. If the system does not hold pressure, check all the fittings with an
electronic helium leak detector. DO NOT use leak detecting liquids.
ElectricalConnections
Before connecting the detector cable to the control
module, make sure that the control module power cord is
unplugged.
1. The heater and filament connections from the detector to the rear panel of
the controller are made up in one cable. After making sure that the control
module power cord is not plugged in, connect this detector cable to the
connector on the control module. The cable connector should be firmly
seated by turning the coupling ring clockwise until the detent is felt.
For best detector performance, the cable and connector
should not be allowed to move while measurements are
being made. If the cable is disconnected, exercise care
to keep the connecting pins in each connector clean.

14
Installation
CHART AB A-B
OUTPUTS
DETECTOR
SERIAL NO.
Valco Instruments Co. Inc.
MODEL NO.
Valco Instruments Co. Inc.
220V
ATTENUATED STRIP
CHART OUTPUT
CABLES FOR A, B,
and AB
RED (+10V)
BLACK ()
WHITE (+1V)
RED (+10V)
BLACK ()
WHITE (+1V)
INLET
AINLET B
CHANNEL
ACHANNEL B
MODEL TCD2-C
115/230 175VA MAX.
T2.0A
250V
MAINS
Figure 9: Electrical connections
2. Connect the data output(s). The A / B / A - B outputs are used with an
integrator or PC-based data acquisition system;the chart output is for a
strip chart recorder. Polarities and full scale range are indicated in the
figure below. (Set the recorder/DAQ for the same voltage scale.)
3. Connectthe main powercord.

15
Installation
Initial Power-Up
SincetheTCD isaconcentration-dependent detector,the lowerthe flow
rate through the detector, the higher the sensitivity. Column diameter will
determinethe optimum columnflowrate.
The microvolumeTCD is designed for the lower flow rates typical for capillary
columns, and achieves best sensitivity at rates below 10 ml/min. Since the
filaments are maintained at constant temperature, the detector can be
operated at extremely low flow rates (less than 0.5 ml/min) without damage
to the filaments.
A - B referenced mode
Flow Rate Settings
1. Measure the column flow at the detector’s Channel A out.The optimum
flow rate is in the range of 4 - 20 mL/min, with the actual rate dependent
on the type of column used.
2. Measure the reference gas flow at Channel B out. It should be as close as
possible to the GC column flow. Use a fixed flow restrictor or a good
quality flow controller to match the the carrier gas and reference gas flows.
3. Once the flows have been established, make sure the filament switch and
the main power switch are in the OFF position, and plug the power cord
into an AC main outlet.
Initial Conditioning
4. Turn on the control module main power switch and set the detector
temperatureto 220°C.
5. Turn on the filament power switch and set both filament temperature knobs
at 8.0.
6. Condition the detector by allowing it to bake at these settings for at least
12hours.
Temperature Settings
7. After the initial bakeout period, set the detector temperature at 100°C or at
thecolumntemperature plus30°, whicheveris higher.
8. Set the filament temperatures at least 50° and as much as 100° higher
than the detector temperature. Refer to Figure 3 on page 5, which
outlinestherelationship betweenthefilament temperature knobsettings
andthe actual filamenttemperature.
Detector sensitivity increases as the temperature differential between the
detector and the filaments increases, but filament life decreases as its
temperature increases.Thus, the detector temperature should be set as
low as possible, determined by the boiling point of the highest boiling
component of the sample.
9. Once all temperatures are set, allow plenty of time for the system to
equilibrate, evidenced by a stable baseline. Typical equilibration time for
going from a cold start-up to 130°C detector temperature is approximately
fivehours. Detectortemperature changestakemuch longer toequilibrate
thando filament temperaturechanges.

16
Installation
Thetest chromatogramaccompanying yourTCD wasobtained under the
followingconditions:
Sample: ~100ppm blend inHeliumbalance
Samplevolume: 250 µl
Column: 10' x 1/16" x 0.040" molecular sieve 5Å micropacked
Column flow: 6 mL/min
Referenceflow: 6 mL/min
Columntemperature: 65°C
Detectortemperature: 100°C
Filament temperature: 230°C (a setting of 5.0)
Carriergas: Helium
Balancing the Channels using LCD Display
The LCD display indicates the signal level from the recorder/chart output.
10. Set the recorder switch to A, and use the coarse and fine controls for
Channel A to adjust the signal level to about 300 mv.
11. Set the recorder switch to B and repeat the same process to adjust the
signal level to about 200 mv.
12. Set the recorder switch to A-B. The display should read about 100 mv. If
the signal levels drifts below zero, readjust the A & B channels.
The detector is now ready for analytical use.
Balancing the Channels using Recorder/Chart Output
10. Usethezero(orshunt)settingontherecordertosetthetruezeroontherecorder.
11. Set the Recorder switch to A, and use the coarse and fine zero controls
for Channel A to bring the recorder pen on scale and to a position
approximately 1-2 cm above zero.
12. Set the Recorder switch to B, and repeat the same process, bringing the
pen to a position half as far above zero as the pen for Channel A.
13. Set the Recorder switch to A - B, and observe the recorder pen position.
It should be above the true zero position, but below the position for
Channel A. If the pen drifts below zero, readjust the A and B channels.
The detector is now ready for analytical use.
Balancing the Channels using Unattenuated Outputs
10. Connect the output cable to the A connector, and use the coarse and fine
zero controls for Channel A to bring the baseline signal on scale and to a
position approximately 100 mV above zero.
11. Move the output cable to the B connector, and use the coarse and fine
zero controls for Channel B to bring the baseline to a position half as far
above zero as for Channel A (the value of A minus B).
12. Move the output cable to the A - B connector, and observe the baseline
signal. It should be above the true zero position. If the signal drifts below
zero, readjust the A and B channels.
The detector is now ready for analytical use.
Single filament mode
Thebasic procedures andtemperature settings describedfor referenced
mode operation can also be applied to operation in the single filament or
independent mode. Both channels must have the same carrier gas; you
cannot use helium carrier in one channel and nitrogen in the other. Also be
aware of the possibility of detector cross-talk when components elute from
the columns in concentrations greater than 1%.