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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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.