Agilent Technologies 7890 Series Operating instructions

Agilent Technologies
Agilent 7890 Series
Gas Chromatograph
Troubleshooting

Notices
© Agilent Technologies, Inc. 2015
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Manual Part Number
G3430-90053
Edition
Third edition, October 2015
Second edition, December 2013
First edition, January 2013
Printed in USA
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Safety Notices
CAUTION
A CAUTION notice denotes a hazard. It
calls attention to an operating
procedure, practice, or the like that, if
not correctly performed or adhered to,
could result in damage to the product
or loss of important data. Do not
proceed beyond a CAUTION notice
until the indicated conditions are fully
understood and met.
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A WARNING notice denotes a hazard.
It calls attention to an operating
procedure, practice, or the like that, if
not correctly performed or adhered
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met.

Agilent 7890 Series Troubleshooting 3
Contents
1 Concepts and General Tasks
Concepts 10
How to troubleshoot using this manual 10
The [Status] key 10
Error conditions 11
Systems Configured for Enhanced Communications 12
Configurable Items to Always Keep Current 13
Inlet and detector configuration 13
Column configuration 13
Automatic Liquid Sampler configuration 14
Gas configuration 14
To View the Run Log, Maintenance Log, and Event Log 15
Run Log 15
Maintenance Log 15
Event Log 15
Information to Obtain Before Calling Agilent for Service 16
2 ALS and Detector Symptoms
Plunger Errors 18
Procedure 18
Vial Mishandled by ALS (7693A) 19
Alignment Light on 7693A/7650A Injector Tower is On 21
Vial Mishandled by ALS (7683) 22
Alignment Light on 7683B Injector Tower is On 24
Syringe Needle Bends During Injection into Inlet 25
FID Fails Leakage Current Test 26
Possible causes 26
Procedure 26
NPD Fails Leakage Current Test 27
FID Fails Baseline Test 28
To Resolve Low Sensitivity with an FID 29
FID Does Not Ignite 30
FID Ignitor Does Not Glow During Ignition Sequence 31

4Agilent 7890 Series Troubleshooting
Corrosion in FID Collector and Ignitor Glow Plug 33
FPD Does Not Ignite 34
NPD Adjust Offset Process Fails 36
NPD Bead Will Not Ignite 37
FPD+Temperature Will Not Become Ready 38
Blinking Not Ready Light: Detector Hardware Fault/TCD Filament
Voltage 39
Shutdown (Defective) Device 40
3 Chromatographic Symptoms
Retention Times Not Repeatable 42
Peak Areas Not Repeatable 43
Contamination or Carryover 44
Isolate the source 44
Check possible causes—all inlet and detector combinations 44
Larger Peaks Than Expected 47
Peaks Not Displayed/No Peaks 48
Baseline Rise During Oven Temperature Program 50
Poor Peak Resolution 51
Peak Tailing 52
NPD Peak Tailing 53
Peak Boiling Point or Molecular Weight Discrimination Poor 54
For any inlet operating in split mode with any detector 54
For any inlet operating in splitless mode with any detector 54
Sample Decomposition in Inlet/Missing Peaks 55
Peak Fronting 56
Noisy Detector, Including Wander, Drift, and Baseline Spikes 57
Noisy baseline 57
Baseline wander and drift 59
Baseline spiking 60
Microcell Electron Capture Detector (uECD) Noise and Sensitivity 63
Display signal evaluation 63
Sensitivity 65
Contamination (high baseline) 66

Agilent 7890 Series Troubleshooting 5
Low Peak Area or Height (Low Sensitivity) 67
To Resolve Low Sensitivity with an FID 68
FID Flame Goes Out During a Run and Attempts to Reignite 70
FID Baseline Output Above 20 pA 72
FID Baseline Output at Maximum (~8 Million) 73
FPD Flame Goes Out During a Run and Attempts to Reignite 74
FPD Quenching/Repeatability 75
FPD Output Too High or Too Low 76
FPD Low Peak Areas 77
FPD Large Peak Width at Half-Height 78
FPD Baseline Output High, > 20 pA 79
NPD Solvent Quenching 80
NPD Response Low 81
NPD Baseline Output > 8 million 83
NPD Adjust Offset Process Not Functioning Properly 84
NPD Low Selectivity 85
Negative Peaks Seen with TCD 86
TCD Baseline Has Dampened Sinusoidal Noise Trailing Peaks (Ringing
Baseline) 87
TCD Peaks Have Negative Dip on Tail 88
4 GC Not Ready Symptoms
GC Never Becomes Ready 90
Flow Never Becomes Ready 91
Oven Temperature Never Cools Down/Cools Very Slowly 92
Oven Never Heats Up 93
Temperature Never Becomes Ready 94
Cannot Set a Flow or Pressure 95
A Gas Does Not Reach Setpoint Pressure or Flow 96
A Gas Exceeds Pressure Setpoint or Flow 97
The Inlet Pressure or Flow Fluctuates 98
Cannot Maintain a Pressure as Low as the Setpoint on a Split Inlet 99

6Agilent 7890 Series Troubleshooting
The Measured Column Flow Does Not Equal the Displayed Flow 100
FID Does Not Ignite 101
FID Ignitor Does Not Glow During Injection Sequence 102
FID or NPD Measured Hydrogen and Makeup Gas Flows Much Less Than
Setpoint 104
NPD Adjust Offset Process Fails 105
FPD Does Not Ignite 106
Valve Not Ready 108
External valves 108
Gas sampling valves 108
Multiposition valve 108
Blinking Not Ready Light: Detector Hardware Fault/TCD Filament
Voltage 109
5 Shutdown Symptoms
Column Shutdowns 112
Hydrogen Shutdowns 114
Hydrogen used in inlets and auxiliary gas streams 114
Hydrogen sensor 115
Detector Air Shutdowns 116
7890B MS Shutdown 117
Clearing an MS Shutdown 118
After resolving an MS Shutdown 118
Thermal Shutdowns 119
6 GC Power On and Communication Symptoms
GC Does Not Turn On 122
PC Cannot Communicate with GC 123
GC Cannot Communicate with a Configured MS or HS 124
GC Does Not Recover After Firmware Update 125
GC Turns On, Then Stops During Startup (During Self-Test) 126

Agilent 7890 Series Troubleshooting 7
7 Checking for Leaks
Leak Check Tips 128
To Check for External Leaks 129
To Check for GC Leaks 131
Leaks in Capillary Flow Fittings 132
To Perform an Inlet Leak Check 133
To set warning limits for a leak check 135
To disable a warning limit for the inlet leak check 135
To Check for Leaks in a Split/Splitless Inlet 136
Cannot Reach Pressure Setpoint 136
Low Sensitivity or Poor Repeatability 137
To Perform a SS Pressure Decay Leak Test 138
To perform a SS inlet pressure decay test at the GC keyboard 138
To Correct Leaks in the Split Splitless Inlet 143
To Check for Leaks in a Multimode Inlet 144
Cannot Reach Pressure Setpoint 144
Low Sensitivity or Poor Repeatability 145
To Perform a MMI Pressure Decay Test 146
To Perform a Multimode Inlet Pressure Decay Test 146
To Correct Leaks in the Multimode Inlet 150
To Perform a PP Pressure Decay Leak Test 151
To Perform a PP Inlet Pressure Decay Test 151
To Correct Leaks in the Packed Column Inlet 155
To Perform a COC Pressure Decay Leak Test 156
To Perform a COC Pressure Decay Test 156
To Correct Leaks in the Cool On-Column Inlet 160
To Perform a PTV Pressure Decay Test 161
To Perform a PTV Pressure Decay Test 161
To Correct Leaks in the PTV Inlet 165
To Perform a VI Pressure Decay Test 166
To Perform a VI Pressure Decay Test 166
To Prepare the VI for a Closed System Leak Check 170
To Correct Leaks in the Volatiles Interface 171

8Agilent 7890 Series Troubleshooting
8 Troubleshooting Tasks
To Measure a Column Flow 174
Measuring FID, TCD, uECD, and FPD column flow 174
Measuring NPD column flow 176
To Measure a Split Vent or Septum Purge Flow 178
To Measure a Detector Flow 180
Measuring FID, TCD, uECD, and FPD flows 180
Measuring NPD flows 183
To Perform the GC Self-Test 185
To Check or Monitor Split Vent Line Backpressure 186
To set a warning limit for the inlet trap check 186
To disable a warning limit for the inlet trap check 188
To Run the Inlet Trap Check 189
To Perform a SS Split Vent Restriction Test 191
To Check a Split Vent Line for Contamination 192
To Adjust the FID Lit Offset 194
To Verify That the FID Flame Is Lit 195
To Verify FID Ignitor Function During Ignition Sequence 196
To Measure FID Leakage Current 197
To Measure FID Baseline Output 198
To Isolate the Cause of FID Noise 199
To Measure NPD Leakage Current 200
To Check for a Plugged FID Jet 201
To Check for a Plugged NPD Jet 202
To Verify That the NPD Bead Is Ignited 203
To Verify That the FPD Flame Is Lit 204
To Adjust the FPD Lit Offset 205
When to Change Gas Purifiers 206
To Ignore a Device’s Readiness State 207
To Use the Stopwatch 208

9
Agilent 7890 Series Gas Chromatograph
Troubleshooting
Agilent Technologies
1
Concepts and General Tasks
Concepts 10
Systems Configured for Enhanced Communications 12
Configurable Items to Always Keep Current 13
To View the Run Log, Maintenance Log, and Event Log 15
Information to Obtain Before Calling Agilent for Service 16

10 Agilent 7890 Series Troubleshooting
1Concepts and General Tasks
Concepts
This manual provides lists of symptoms and corresponding
tasks to perform should you experience errors associated with
GC hardware or chromatographic output, GC Not Ready
messages, and other common issues.
Each section describes a problem and provides a bulleted list of
possible causes for you to troubleshoot. These lists are not
intended for use in the development of new methods. Proceed
with troubleshooting under the assumption that method(s) are
working properly.
This manual also includes common troubleshooting tasks as
well as information needed prior to calling Agilent for service.
While this manual describes troubleshooting for 7890 Series
GCs in general, when describing GC keyboard usage and
firmware features, this manual assumes a 7890B GC using
firmware B.02.01. Features that are specific to one GC model
only (7890A or 7890B) are noted.
How to troubleshoot using this manual
Use the following steps as a general approach to
troubleshooting:
1Observe the symptoms of the problem.
2Look up the symptoms in this manual using the Table of
Contents or the Search tool. Review the list of possible causes
of the symptom.
3Check each possible cause or perform a test that narrows the
list of possible causes until the symptom is resolved.
The [Status] key
Be sure to also use the [Status] and [Info] keys on the GC keypad
while using this troubleshooting information. These keys will
display additional useful information related to the status of the
GC and its components.

Concepts and General Tasks 1
Agilent 7890 Series Troubleshooting 11
Error conditions
If a problem occurs, a status message appears. If the message
indicates broken hardware, more information may be available.
Press the applicable component key (for example, [Front Det],
[Oven], or [Front Inlet]).

12 Agilent 7890 Series Troubleshooting
1Concepts and General Tasks
Systems Configured for Enhanced Communications
When configured with other instruments that support enhanced
communications, such as a 5977 MSD, 7000C Triple Quadrupole
MS, and 7697 Headspace Sampler, the 7890B GC and configured
instruments closely interact with each other. In addition to
simply sending start run commands and general status
information (ready or not ready), the instruments change their
settings based on each other’s status. For example:
•A GC shutdown may cause an MS to shut down or otherwise
protect itself.
•Venting an MS causes changes in the GC to support the
venting process.
•An MS shutdown may cause the GC to change its settings to
protect itself and the MS.
•A loss of communications between the instruments may
causes changes in one or both instruments.
•The GC sleep/wake cycle triggers the MS and HS sleep/wake
cycle (if available).
•A configured headspace sampler determines its timings
based on the loaded GC method.
Because of this interaction, always check the displays on all
instruments and in the data system to learn the complete
system status. In general, the GC display will present
configured instrument status messages as well as its own
messages.

Concepts and General Tasks 1
Agilent 7890 Series Troubleshooting 13
Configurable Items to Always Keep Current
Certain configurable items in the GC must always be kept
current. Failure to do so will lead to reduced sensitivity,
chromatographic errors, and possible safety concerns.
If equipped with the optional G3494A or G3494B Barcode
Reader accessory (7890B only), you can directly scan parts data
(column, liner and ALS syringe information) into the GC
without having to type it into the GC at the keypad.
Inlet and detector configuration
Be sure to configure the GC and all related components to
reflect an inlet or detector change. Below are some examples of
components to keep current after making changes to the inlet or
detector:
Liners: The appropriateness of liner type varies depending on
the GC inlet mode, for example split mode versus splitless
mode, and the analysis.
FPD filters: The FPD filters require different gas flows to
function properly. Configure the flow according to the FPD
filter installed (phosphorus versus sulfur).
FID and NPD jets: Use the jet appropriate for the type of
column installed (capillary column versus packed column).
NPD bead type: Always configure the NPD bead type. An
incorrect type can lead to poor performance or premature bead
failure.
Column configuration
Reconfigure the GC every time a column is trimmed or changed.
Also verify that the data system reflects the correct column
type, length, id, and film thickness. The GC relies on this
information to calculate flows. Not updating the GC after
altering a column causes incorrect flows, changed or incorrect
split ratios, retention time changes, and peak shifts.

14 Agilent 7890 Series Troubleshooting
1Concepts and General Tasks
Automatic Liquid Sampler configuration
Keep the Automatic Liquid Sampler (ALS) configuration
up-to-date to ensure proper operation. ALS items to keep
current include injector position, installed syringe size, and
solvent and waste bottle usage.
Gas configuration
Reconfigure the GC every time the gas type is changed. If the GC
is configured to a gas other than what is actually being
plumbed, incorrect flow rates will result.
To confirm the gas configuration:
1Press [Config].
2Scroll to the appropriate detector or column item on the
display and press [Enter] to see the type of gas configured.
WARNING
Always configure the GC appropriately when working with
hydrogen. Hydrogen leaks quickly and poses a safety concern if
too much of it is released into the air or into the GC oven.

Concepts and General Tasks 1
Agilent 7890 Series Troubleshooting 15
To View the Run Log, Maintenance Log, and Event Log
The GC maintains internal event logs, each of which holds up to
250 entries. Use these logs to troubleshoot problems, especially
when a message no longer appears on the display.
To access the logs, press [Logs] to toggle to the desired log. The
display will indicate the number of entries the log contains.
Scroll through the list.
Run Log
For each run, the run log records deviations from the planned
method. This log is overwritten at the start of each run. The run
log information can be used for Good Laboratory Practice (GLP)
standards and can be uploaded to an Agilent data system. When
the Run Log contains entries, the Run Log LED lights.
Maintenance Log
The maintenance log contains an entry for each time an Early
Maintenance Feedback limit is reached, reset, or changed. The
log records details such as the counter item, the counter value,
the new counter value, and whether or not the counter was
reset (indicating a part replacement). When the maintenance
log is full, the GC overwrites entries, beginning with the oldest.
Event Log
The event log records events such as shutdowns, warnings,
faults, and GC state changes (start run, stop run, and so forth)
that occur during GC operation. When the event log is full, the
GC overwrites entries, beginning with the oldest.

16 Agilent 7890 Series Troubleshooting
1Concepts and General Tasks
Information to Obtain Before Calling Agilent for Service
Gather the following information before contacting Agilent for
service:
•Symptoms
•Problem description
•Hardware installed and parameters/configuration when the
error occurred (sample, supply gas type, gas flow rates,
detectors/inlets installed, and so forth)
•Any messages that appear on the GC display
•Results of any troubleshooting tests you have run
•Instrument details. Obtain the following information:
•GC serial number, which can be found on a sticker located
beneath the keypad on the bottom right corner of the GC.
•GC firmware revision (press [Status], then [Clear])
•GC power configuration (located on a label on the back
panel of the GC to the left of the GC power cable)
•Oven configuration (fast- or slow-heating)
•Press the [Status] key to display previous Error, Not Ready, and
Shutdown messages.
To obtain service/support contact numbers, see the Agilent Web
site at www.agilent.com/chem.

17
Agilent 7890 Series Gas Chromatograph
Troubleshooting
Agilent Technologies
2
ALS and Detector Symptoms
Plunger Errors 18
Vial Mishandled by ALS (7693A) 19
Alignment Light on 7693A/7650A Injector Tower is On 21
Vial Mishandled by ALS (7683) 22
Alignment Light on 7683B Injector Tower is On 24
Syringe Needle Bends During Injection into Inlet 25
FID Fails Leakage Current Test 26
NPD Fails Leakage Current Test 27
FID Fails Baseline Test 28
To Resolve Low Sensitivity with an FID 29
FID Does Not Ignite 30
FID Ignitor Does Not Glow During Ignition Sequence 31
Corrosion in FID Collector and Ignitor Glow Plug 33
FPD Does Not Ignite 34
NPD Adjust Offset Process Fails 36
NPD Bead Will Not Ignite 37
FPD+Temperature Will Not Become Ready 38
Shutdown (Defective) Device 40

18 Agilent 7890 Series Troubleshooting
2ALS and Detector Symptoms
Plunger Errors
If the ALS reports a front or back plunger error, check the
following possible causes:
•The syringe plunger is sticking or is not securely connected
to the plunger carrier.
•The plunger solenoid is binding.
•The plunger carrier encoder is inoperable.
•The autoinjector plunger carrier mechanism will not move.
•The plunger does not move freely due to sample residue or
wear. Install a new syringe, making sure to prime the syringe
with solvent before installing.
Procedure
1Remove the syringe and check it for plunger stickiness or
binding. Replace the syringe if necessary (7693A, 7650A,
7683).
2Check the viscosity of the sample against the viscosity
parameter. Reset the viscosity parameter if necessary.
3Restart the sequence.
4If the error occurs again, obtain Agilent service.

ALS and Detector Symptoms 2
Agilent 7890 Series Troubleshooting 19
Vial Mishandled by ALS (7693A)
Refer to your sampler operating documentation for additional
information.
When you find a mishandled sample vial, do the following:
•Check for folds or wrinkles in the crimp cap, especially near
the neck of the sample vial.
•Use Agilent-recommended sample vials.
The figure below shows the critical dimensions for sample
vials and microvial inserts to be used with the 7693A ALS
system. These dimensions do not make up a complete set of
specifications.
•Verify the transfer turret is installed if using a G4514A tray.
•Check sample labels (if applicable).
•Check that they are the correct size.
•Verify that the labels do not interfere with the gripper.
Vials are available with a write-on spot for easy marking. If
you choose to make and apply your own labels, Agilent
Technologies recommends the positioning and maximum
label thickness shown in the figure below.
Body Diameter (BD) = 11.7 ± 0.2
Cap Diameter (CD) = BD × 1.03 maximum
All dimensions in millimeters
CD
BD
33.5 ± 1.5
Vial plus cap height
6.25 ± 0.25
3.7 min.
8.2 ± 0.2
32 ± 0.5
11.7 ± 0.2
25 minimum
body height
Maximum height of a capped vial Crimp cap sample vial

20 Agilent 7890 Series Troubleshooting
2ALS and Detector Symptoms
•Check that the tray vial racks are clean and snapped into the
tray base.
•Calibrate the system.
All dimensions in millimeters
Overlap mismatch
1.0 max.
Label skew
26.6 max.
3.6 min.
13.4 minimum
No label or tape
16.4 ± 0.5
13.2 maximum
Text areas are optional
Text
Bar code
Text
12.56
Maximum width
measured at overlap