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Tips and Tricks of Troubleshooting
the GC System & Injector Maintenance
Jigar Patel
Page 1
Precautions
Use High(99.9995%) purity gases
Perform regular inlet and detector maintenance
Replace the consumables
Column
Reduce the Power switching of GC
Maintain the log, Replace the gas line filters regularly
Page 2
Gases and filters
Page 3
GC InstallationCarrier Gas, purity 99.9995%
Moisture TrapP/N 5060-9084
Indicating O2 TrapP/N IOT-2-HP1/8” Copper Tubing
P/N 5180-4196
Two 0100-2144 1/8-inch ball valves
1/8” Swagelok -NPT Adapter
Stainless Steel DiaphragmTank Regulator
Page 4
Gas purification panels
Inline Filters
Determine desired purity levelKeep number of fittings in gas line to a minimumInstall purifiers in a convenient location close to the GCUse purifier log books to determine maintenance and cartridge replacement schedulesUse indicating traps closest to the GC so you can determine when to change the traps that are upstream
Page 5
Columns
Page 6
GC Capillary Column Preparation
Created 5//02
Ceramic Column CutterRough Edge
New Column Ferrule
Column Nut
Septum to mark Column Position
1) Slide a used Septum over thecolumn as a marker2) Slide a Column Nut onto the column3) Slide a new Column Ferruleonto the column4) Score the column and snap offthe end5) Inspect the column for a cleancut.
Page 7
6850/90/7890 Column Installation Dimensions-Inlets
Inlet
Detector
PPIP Split/Splitless PCOC PTV VI
TCD FID NPD uECD FPD
Height
Height
1-2 mm 4-6 mm All the way - until spring tension is felt
153 mmAll the wayback off 1-2 mm
All the wayback off 1-2 mm
All the wayback off 1-2 mm
All the wayback off 1-2 mm
6 mm17 mm
Inlets
Detectors
Original ECD
2 mm pasttip of MUG adapter
Page 8
6850/90/7890 Column Installation Dimensions-FID
mm
010
2030
4050
mm
010
2030
4050
6070
48mm68mm 1mm
Column Installation Video
General Rule:Push to tip of JetThen withdraw 1 mm
Capillary Optimized FID Adaptable FID
Page 9
Column connection to Inlet
Page 10
Column front end
Important……..Electronic Pneumatic Control….Fundamental Principle - 6850/90 Capillary Column Flow is Never Measured by the GC -It is always calculated and controlled by Inlet Pressure…...
Fundamental Inlet Specification;Pressure Accuracy: +/- 2% Full ScaleColumn Flow - NO SPECIFICATION
6850/6890 Inlet EPC calculates column flow based on:
Column ID - most effect – r2 “Squared Function”Column LengthFilm Thickness (usually negligible)Column Oven TempInlet PressurePressure at exit of column (usually 1 ATM)Ambient Pressure and Temperature (NTP)
Page 11
Consumables
Page 12
Septa
Page 13
Consumables
Septa related problems
Page 14
Ferrule
Page 15
LinersSplit less
Split
Page 16
Use vapor volume calculator
•Liners become contaminated with use, collecting non-volatiles, salts, excess reagents, etc., or become damaged/cracked.
•Should inspect and replace liners often.
•Handle with gloves and forceps.
•Insert or remove liners only from cool injection ports.
•Replacing with a new liner is recommended, to ensure reproducibility
Liner Maintenance
Page 17
Turn Top Inlet Sealing Systemon NEW 7890
- Fast/Easy Split/Splitless Inlet Maintenance
… changing liners has never been easier
Page 18
Replace Because…Most Common Causes of Leaks
Re-use and mis-installation.• Leak from O-ring, Gold Seal, ferrules, column nuts• O-rings are elastomer compression fittings designed for one use, not
perfectly elastic. • Gold seals are designed for one use, knife edge cuts into gold layer
giving leak tight seal w/o shrinkage or potential organic contaminants from polyimide out-gassing/degradation.
• Re-using could result in overlap in seal rings, resulting in a leak.• Over-tightening of fittings
Page 19
Split Vent Trap
Page 20
Replacing the Split Vent Trap
Finger Tight Nut
G1544-80530
Page 21
Jet type Part no. Jet tip idCapillary G1531-80560 0.29 mm (0.011-inch)Capillary - High-temperature G1531-80620 0.47 mm (0.018-inch)
Jet type Part no. Jet tip idCapillary 19244-80560 0.29 mm (0.011-inch)Capillary - High-temperature
(use with simulated distillation)
19244-80620 0.47 mm (0.018-inch)
Packed 18710-20119 0.47 mm (0.018-inch)Packed wide-bore
(use with high-bleed applications)
18789-80070 0.030-inch
FID Jet Selection GuideThere are two types of FID available.capillary optimized FID is only used with capillary columns, and adaptable FID fits packed columns and can be adapted to fit capillary columns.
Jets for the Capillary-Optimized FID
Jets for the Adaptable FID
Page 22
GC Inlets
Page 23
Page 24
Where Does it Get Dirty?
Here
Here
Here
Here
Here
Page 25
Maintenance??
Inlet S/SL GC6890/50/7890 Shutdown!!
Mode: SplitTemp 250 250Pressure 3.2 10.0Split Ratio 100 Split Flow 200Tot Flow 205.0 205.0Gas Saver ONSaver Flow 50.0Saver Time 0.5
Fault: Back inlet pressure shutdown
Mode: SplitTemp 250 250Pressure 9.2 2.6Split Ratio 100 Split Flow 200Tot Flow 205.0 205.0Gas Saver ONSaver Flow 50.0Saver Time 0.5
Fault: Back inlet pressure shutoff
Page 26
GC Detector- FID
Page 27
Detector-FIDFID Flow Measurement Tool
H2 and Makeup GasFrom FID EPC module
Flow between the jet and the outside of the column
Inlet EPC/Carrier Control
FID Air
Column/Makeup and H2 Flows
Page 28
1 – Set H2 to 75 ml/minColumn can remain installed – OR the FID can be capped – keep in mind that jet plugging can be due to a column that is installed all the way to the tip of the Jet!
6850/6890 Jet Plugging Diagnostic – can also be run from 6890 Front Panel or GC Chemstation
Page 29
6850/6890 Jet Plugging Diagnostic
2 – Turn Makeup Gas to OFF
Page 30
6850/6890 Jet Plugging Diagnostic
3 – Monitor Makeup Flow readout (or actual pressure)
Page 31
6850/6890 Jet Plugging Diagnostic
3 – Monitor Makeup Flow readout (or actual pressure)If the Jet is not plugged – all H2 flow will exit the jet and Makeup pressure will be close to 0 PSI (display reading 0 ml/min.)
Page 32
6850/6890 Jet Plugging Diagnostic
3 – Monitor Makeup Flow readout (or actual pressure)If the Jet is plugged, or the column is installed too high – H2 pressure will back up and be indicated as a flow/pressure on the Makeup Gas Channel
A positive Pressure (Flow Readout) will be indicated on Makeup Gas Sensor
Page 33
Flame Ignition problem
Page 34
Measure flow – H2, AirJet Chocking – How to clean?Does ignitor glow plug working?Are column and fittings are leak free?Cylinder pressures are enough?
General problems
Page 35
Troubleshooting and Precautions
RT Variation
Area variation
Noise/Spikes
Low response
Peak splitting
Inlet pressure shutdown
Page 36
RT Variation
Improper flow
Jet chocking
Column Parameters
Page 37
Area variation
Peak pattern/column issue
ALS maintenance-Inj. Vol. variation
Page 38
Pressure variation
Leak
EPC
Page 39
Low response
Sample
Inj. volume
Leak
Jet chocking
Page 40
Peak splitting
Column
Column connection
Inlet-Liner
Page 41
Baseline noise/spikes
Detector cleaning
Column conditioning
Inlet cleaning
Gas Purity
Page 42
Questions
Page 43
All videos are available at below linkhttp://www.chem.agilent.com/en-US/Support/Installation/Pages/default.aspx