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