Agilent Technologies 7890A Operating instructions

Agilent Technologies
Agilent 7890A
Gas Chromatograph
Troubleshooting

Notices
© Agilent Technologies, Inc. 2009
No part of this manual may be reproduced
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Manual Part Number
G3430-90014
Edition
Third edition, April 2009
Second edition, May 2008
First edition, March 2007
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
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A WARNING notice denotes a hazard.
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procedure, practice, or the like that, if
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Do not proceed beyond a WARNING
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Troubleshooting 3
Contents
1 Concepts and General Tasks
Concepts 10
How to troubleshoot using this manual 10
The [Status] key 10
Configurable Items to Always Keep Current 11
Column configuration 11
Automatic Liquid Sampler configuration 11
Gas configuration 11
To View the Run Log, Maintenance Log, and Event Log 12
Information to Obtain Before Calling Agilent for Service 13
2 ALS and Detector Symptoms
Plunger Errors 16
Vial Mishandled by ALS 17
Syringe Needle Bends During Injection into Inlet 18
FID Does Not Ignite 19
FID Ignitor Does Not Glow During Ignition Sequence 20
Corrosion in FID Collector and Ignitor Glow Plug 21
FPD Does Not Ignite 22
NPD Adjust Offset Process Fails 23
3 Chromatographic Symptoms
Retention Times Not Repeatable 26
Peak Areas Not Repeatable 27
Contamination or Carryover 28
Isolate the source 28
Check possible causes—all inlet and detector combinations 28
Larger Peaks Than Expected 30
Peaks Not Displayed/No Peaks 31
Table 1. Detector troubleshooting 31

4Troubleshooting
Baseline Rise During Oven Temperature Program 32
Poor Peak Resolution 33
Peak Tailing 34
NPD 34
Peak Boiling Point or Molecular Weight Discrimination Poor 35
For any inlet operating in split mode with any detector 35
For any inlet operating in splitless mode with any detector 35
Sample Decomposition in Inlet/Missing Peaks 36
Peak Fronting 37
Noisy Detector, Including Wander, Drift, and Baseline Spikes 38
Noisy baseline 38
Baseline wander and drift 39
Baseline spiking 40
Figure 1. Cyclic spiking 40
Figure 2. Random spiking 40
Low Peak Area or Height (Low Sensitivity) 41
FID Flame Goes Out During a Run and Attempts to Reignite 43
FID Baseline Output Above 20 pA 44
FPD Flame Goes Out During a Run and Attempts to Reignite 45
FPD Output Too High or Too Low 46
FPD Low Peak Areas 47
FPD Large Peak Width at Half-Height 48
FPD Baseline Output High, > 20 pA 49
NPD Solvent Quenching 50
NPD Response Low 51
NPD Baseline Output > 8 million 52
NPD Adjust Offset Process Not Functioning Properly 53
NPD Low Selectivity 54
Negative Peaks Seen with TCD 55
TCD Baseline Has Dampened Sinusoidal Noise Trailing Peaks (Ringing
Baseline) 56
TCD Peaks Have Negative Dip on Tail 57
4 GC Not Ready Symptoms
GC Never Becomes Ready 60

Troubleshooting 5
Flow Never Becomes Ready 61
Oven Temperature Never Cools Down/Cools Very Slowly 62
Oven Never Heats Up 63
Temperature Never Becomes Ready 64
Cannot Set a Flow or Pressure 65
A Gas Does Not Reach Setpoint Pressure or Flow 66
A Gas Exceeds Pressure Setpoint or Flow 67
The Inlet Pressure or Flow Fluctuates 68
Cannot Maintain a Pressure as Low as the Setpoint on a Split Inlet 69
The Measured Column Flow Does Not Equal the Displayed Flow 70
FID Does Not Ignite 71
FID Ignitor Does Not Glow During Injection Sequence 72
NPD Adjust Offset Process Fails 73
FPD Does Not Ignite 74
5 Shutdown Symptoms
Column Shutdowns 76
Hydrogen Shutdowns 77
Thermal Shutdowns 79
6 GC Power On and Communication Symptoms
GC Does Not Turn On 82
GC Turns On, Then Stops During Startup (During Self-Test) 83
PC Cannot Communicate with GC 84
7 Checking for Leaks
Leak Check Tips 86
To Check for External Leaks 87
To Check for GC Leaks 89
Leaks in Capillary Flow Fittings 90
8 Troubleshooting Tasks
To Measure a Column Flow 92
Measuring FID, TCD, uECD, and FPD column flow 92
Measuring NPD column flow 94
To Measure a Split Vent or Septum Purge Flow 96

6Troubleshooting
To Measure a Detector Flow 98
Measuring FID, TCD, uECD, and FPD flows 98
Measuring NPD flows 100
To Perform the GC Self-Test 102
To Adjust the FID Lit Offset 103
To Verify That the FID Flame Is Lit 104
To Verify FID Ignitor Function During Ignition Sequence 105
To Measure FID Leakage Current 106
To Measure FID Baseline Output 107
To Measure NPD Leakage Current 108
To Verify That the NPD Bead Is Ignited 109
To Verify That the FPD Flame Is Lit 110
To Adjust the FPD Lit Offset 111

Troubleshooting 7

8Troubleshooting

9
Agilent 7890A Gas Chromatograph
Troubleshooting
Agilent Technologies
1
Concepts and General Tasks
Concepts 10
Configurable Items to Always Keep Current 11
To View the Run Log, Maintenance Log, and Event Log 12
Information to Obtain Before Calling Agilent for Service 13

10 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.
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.