Agilent 6850 GC Service Manual [PDF]

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Agilent 6850 Gas Chromatograph Service Information Contents Introduction

Electronics

Covers

G2629A Control Module

Inlets and valves

Manuals and other parts

Detectors

Troubleshooting

Oven Released: DEC 2002 Part No. G2630-90648

0

Introduction

1

About this manual About this edition Safety information Sound Emission Certification for Federal Republic of Germany Electromagnetic compatibility Safety symbols How to use this manual Tools and test equipment

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

1–1

This manual is intended for use only by Agilenttrained service personnel who are familiar with the physical and safety requirements of working on the 6850 series gas chromatograph (GC).

Replaces Part No. G2630-90647.

Safety information

These procedures supplement the operation and maintenance information found in the 6850A GC User Information and 6850A Control Module User Information CD-ROMs.

The Agilent 6850 Gas Chromatograph meets the following IEC (International Electrotechnical Commission) classifications: Safety Class 1, Transient Overvoltage Category II, and Pollution Degree 2.

About this edition

This unit has been designed and tested in accordance with recognized safety standards and designed for non-classified indoor use. If the instrument is used in a manner not specified by the manufacturer, the protection provided by the instrument may be impaired. Whenever the safety protection of the 6850 has been compromised, disconnect the unit from all power

© Agilent Technologies 1999-2002 All Rights Reserved. Reproduction, adaptation, or translation without permission is prohibited, except as allowed under the copyright laws. Part No. G2630-90648 Released: DEC 2002

6850 Gas Chromatograph Service Procedures

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6850

First edition, DEC 2002

Introduction

About this manual

Sound Emission Certification for Federal Republic of Germany

Refer servicing to qualified service personnel. Substituting parts or performing any unauthorized modification to the instrument may result in a safety hazard. Disconnect the AC power cord before removing covers. The customer should not attempt to replace the battery or fuses in this instrument. The battery contained in this instrument is recyclable. The unit and all of its components should be shipped back to the Agilent factory for recycling.

Sound pressure Lp < 48 dB(A) During normal operation At the operator position According to ISO 7779 (Type Test) When operating the 6850 GC with cryo valve option, the sound pressure 92.5 dB(A) during cryo valve operation for short burst pulses. Schallemission Schalldruckpegel LP < 48 dB(A) Am Arbeitsplatz Normaler Betrieb Nach DIN 45635 T. 19 (Typprüfung) Bei Betrieb des 6850 mit Cryo Ventil Option treten beim Oeffnen des Ventils impulsfoermig Schalldrucke Lp bis ca. 92.5 dB(A) auf.

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

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Introduction

The instrument weighs approximately 23 kg (50 lbs) and therefore should be moved in an upright position by two people supporting the bottom of the unit.

6850

sources and secure the unit against unintended operation.

1. This device may not cause harmful interference. 2. This device must accept any interference received, including interference that may cause undesired operation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try one or more of the following measures: 1. Relocate the radio or television antenna.

Released: DEC 2002

3. Plug the device into a different electrical outlet, so that the device and the radio or television are on separate electrical circuits.

6850

This device complies with the requirements of CISPR 11. Operation is subject to the following two conditions:

2. Move the device away from the radio or television.

4. Make sure that all peripheral devices are also certified. 5. Make sure that appropriate cables are used to connect the device to peripheral equipment. 6. Consult your equipment dealer, Agilent Technologies, or an experienced technician for assistance. 7. Changes or modifications not expressly approved by Agilent Technologies could void the user’s authority to operate the equipment.

6850 Gas Chromatograph Service Procedures

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Introduction

Electromagnetic compatibility

Caution

Warnings in the manual or on the instrument must be observed during all phases of operation, service, and repair of this instrument. Failure to comply with these precautions violates both the safety standards of design and the intended use of the instrument. Agilent Technologies assumes no liability for the customer's failure to comply with these requirements.

A caution calls attention to a condition or possible situation that could damage or destroy the product or the user's work.

6850

Safety symbols

See accompanying instructions for more information.

Introduction

WARNING

A warning calls attention to a condition or possible situation that could cause injury to the user.

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6850 Gas Chromatograph Service Procedures

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Indicates a hot surface. Indicates hazardous voltages. Pinch hazard.

Hot-links used in this manual are shown in blue for easy identification. Most hot links are jumps to other locations in this manual, but some are links to other documents. Once you are in another file, you can return to this document by clicking on the “Service Manual” bookmark or by clicking the Acrobat “Go to Previous View” button until you reach the correct page.

6850

The following symbols used on the instrument indicate potential safety hazards.

Indicates a radioactive hazard. Indicates an explosion hazard

Introduction

How to use this manual To search all files on this CD-ROM for a topic, click on the icon in the menu bar to launch the multifile search engine.

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6850 Gas Chromatograph Service Procedures

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T-10 and T-20 Torx drivers Inlet wrench

Table 1-1. Tools required

Blanking plug, finger-tight style

1/2-inch x 7/16-inch open end wrench

ESD protective wrist strap

1/8-inch allen wrench

Ferrule, no hole or plug

3/16-inch wrench

FID flow measuring insert

3-mm allen wrench for actuator

MPC plumbing kit

5/16-inch x 1/4-inch open end wrench

Plug, 1/8-inch brass (6-pack)

7/16-inch wrench x 3/8-inch open end wrench

Pneumatic LK test kit

9/16-inch x 5/8-inch open end wrench

Tube, assembly tool PTFE

9/16-inch x 7/16-inch open end wrench

Tweezers

Flat blade screwdriver

Volt/Ohm meter

1/4-inch hex nut driver

Flow Tracker 1000 Flowmeter

7-mm hex nut driver

Handheld electronic leak detector, 110 V

No. 1 Posidriv screwdriver

Handheld electronic leak detector, 220 V

No. 2 Posidriv screwdriver, 4-inch shaft

Agilent GC Firmware Update Utility 3.x

6850 Gas Chromatograph Service Procedures

Introduction

Column cutter

1/2-inch adjustable wrench

Released: DEC 2002

6850

Tools and test equipment

1–7

Covers

2

Replacement Parts

Replacement Procedures

External covers

Back cover

Internal covers

Raising the lid to the service position

Detector electronic cover and column hanger

Electronics cover

Connector cover plates (in lid)

Front cover (with keyboard and display) Lid top cover

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

2–1

6850

Replacement parts External covers Detector cover G2630–40140

Screw, shoulder, M4 x 9 mm 0515–3005 HP 6850 Series G C S ys t e m

Marquee G2630–40170

Covers

Front panel housing G2630–60630

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6850 Gas Chromatograph Service Procedures

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6850

External covers, continued

Screws, M4 × 12 mm 0515–2496

3-way valve assembly mount G2630–80640

Back panel G2630–00030

Released: DEC 2002

Covers

CO-EZ-11AA MICRO ENET 2CH Ethernet Address: 00-00-00-00-00-00 0000-000

S/N 6205464

Supply tubing assembly G2630–60650

LAN

6850 Gas Chromatograph Service Procedures

2–3

6850

Internal covers

Lid switch pin G2630–20870

Covers

Detector electronics cover G2630–00290

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6850 Gas Chromatograph Service Procedures

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6850

Internal covers, continued

Electronics cover G2630–00220

Covers

Switch assembly 3101–3558

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6850 Gas Chromatograph Service Procedures

2–5

6850

Detector electronic cover and column hanger

Detector electronics cover G2630–00290

Covers

Column hanger, obsolete, order G2630-80800

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

2–6

6850

Connector cover plates (in lid)

Screw, M4 x 12 mm (8 places) 0515–2556

Covers

Pneumatics connector covers G2630–00680

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6850 Gas Chromatograph Service Procedures

2–7

3. The back cover is secured by seven T-20 Torx screws.

6850

Replacement procedures Back cover

Remove

WARNING

LAN

Covers

2. Turn off all supply gases at their sources, then disconnect all gases from the bulkhead connectors on the back of the instrument.

CO-EZ-11AA MICRO ENET 2CH Ethernet Address: 00-00-00-00-00-00 0000-000

1. Disconnect all cables from the back of the instrument.

S/N 6205464

Shock hazard. Before beginning, turn off the instrument and disconnect the power cord.

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6850 Gas Chromatograph Service Procedures

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WARNING Do not work on the instrument unless the stop plate is raised, preventing the lid from accidentally falling closed while you are working. When closing the lid, have someone else hold the lid for you.

Check behind the lid to make sure the area is clear of obstructions before opening the lid to the service position. 1. Open the lid. 2. Loosen the screw on the side of the counterbalance cam that secures the stop plate. The stop plate will drop down. Raise the cover to the full upright service position. See the figure below.

Covers

Never disconnect the safety wire. If the safety wire is disconnected, the GC can become unbalanced.

Caution

6850

Raising the lid to the service position

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6850 Gas Chromatograph Service Procedures

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WARNING Shock hazard. Before beginning, turn off the instrument and disconnect the power cord.

6850

Electronics cover

To remove the electronics cover: Stop plate Screw

1. Open the lid. 2. Raise the lid to the service position. See “Raising the lid to the service position” on page 2-9 for details.

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

Covers

3. When servicing is complete, move the lid to the normal open position and slide the stop plate all the way up into position behind the roller. Tighten the stop plate screw. 2–10

6850

3. Remove the two T-20 Torx screws shown below and loosen the two 7 mm nuts.

Remove screws

Loosen nuts

Covers

4. Slide the electronics cover off the instrument.

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6850 Gas Chromatograph Service Procedures

2–11

Front cover (with keyboard and display) WARNING

Disconnect

Burn hazard. The oven may be very hot. Before beginning, turn off the oven and allow it to cool.

6850

5. Disconnect the cover switch connectors.

To remove the front cover: 1. Unscrew the two T-20 Torx screws at the bottom of the front cover.

Caution

Covers

Be careful not to pull the metal contacts off of the switch when disconnecting the wires.

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6850 Gas Chromatograph Service Procedures

2–12

6850

Front cover

Remove

2. Open the lid.

4. Press the two lid latch release buttons until they disengage from the front panel.

3. Remove the two T-20 Torx screws in the top of the front cover.

5. Slide the panel forward and down. Disconnect the main ribbon cable from the display. 6. Remove the panel from the instrument.

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

2–13

Covers

Remove these screws

6850

To install the front cover: 1. Connect the ribbon cable to the display. 2. Insert the lower edge of the front cover first, then tilt up into place. Depress the lid latch release buttons, if needed. The buttons should work the latches freely.

Covers

3. Install the four mounting screws.

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

2–14

Remove vent lines, if installed

6850

Lid top cover

Remove T-20 Torx screws (8 places)

Lift off detector cover (if desired)

Covers

Lid top cover without valve box accessory is shown

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

2–15

Inlets and valves Replacement Parts

3 Replacement Procedures

Split/splitless inlet

Injection port cooling fan

Purged/packed inlet

Split/splitless inlet

Purged packed inlet flow manifold

Inlet insert weldment

Replacement parts for any inlet flow manifold

Shell weldment

Fans

Purged packed inlet service Inlet assembly and flow manifold removal

Sampling valves Direct Valve-to-Column Connector Kit

Inlet and flow manifold installation Inlet weldment Direct Valve To Column Connector Kit

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

3–1

15. Inlet liner, split mode, standard*

Split/splitless inlet Description

Part No.

Qty.

1.

O-rings (10/pk)

5180-4181

1

2.

Nut, Merlin Microseal

5182-3445

–

3.

Septum, Merlin Microseal

5182-3444

–

4.

Screw, M3 × 16 mm, Torx T-10

1390-1022

1

5.

Plastic fitting (10/pk) 5181-3394 Split vent trap assembly G1544-80550 Replacement filter cartridge kit (2/pk) G1544-80530 Split vent flow line G1544-20620 (14.2 in. long × 0.125 in. id) Swagelok nut, 1/8 in. brass (10/pk) 5180-4103

6. 7. 8. 9.

1 1 – 1

5180-4115

1

5180-4109

1

11. Septum nut

18740-60835

1

12. Septum, 11 mm, solid, (25/pk)*

5181-1263

1

13. Top insert assembly Top insert assembly, for 6850 valve box (not shown) 14. 1/4-inch Viton O-ring,* (order no. 5180-4182, 12/pk)

G1544-60585 G2630-61080

1 –

5180-4182

1

Released: DEC 2002

Qty.

5183-4647

1

*Also see the Agilent chemical analysis consumables and accessories catalog.

1 2 3 4

11 12 5 13 14

6

1

Swagelok back ferrule, 1/8-in. brass (10/pk) 10. Swagelok front ferrule, 1/8-in. brass (10/pk)

Part No.

6850

Description

8 9 10

7

15

Continued

6850 Gas Chromatograph Service Procedures

3–2

Inlets and valves

Replacement parts

Part No.

Qty.

16

16. Screw, M4 x 12 mm, Torx T-20 (Captive)

1390-1023

3

17

17. Inlet weldment

G1544-80570

1

18. Heater/Sensor assembly

G1544-61140

1

19. Screw, M4 x 8 mm, Torx T-20, chrome plated

0515-2711

3

20. Washer, 12/pk

5061-5869

1

21. Thermal block

G1544-20570

1

22. Block insulation

G1544-00020

1

23. Insulation, lower

G1544-00030

1

24. Top insulation

G1544-00010

1

18 24

19 20 21

Inlets and valves

Description

22

23 Continued

Released: DEC 2002

6850

Split/splitless inlet, continued

6850 Gas Chromatograph Service Procedures

3–3

Part No.

Qty.

19. Screw, M4 x 8 mm, Torx T-20, chrome plated

0515-2711

3

25. Thermal nut

G1544-20590

1

26. Lower inlet seal, gold plated Also in stainless steel (optional)

18740-20885 18740-20880

1 –

27. Flat thrust washer (Order no. 5061-5869, 12/pk)

2190-0464

1

28. Reducing nut

18740-20800

1

29. Insulation, order qty 3

19243-00067

3

30. Bottom insulation cover

19243-00070

1

31. Ferrules (identify by internal dia.):* Solid (no hole) ferrule plug 5181-7458 Graphite ferrule 0.5 mm id (10/pk) 5080-8853 Graphite ferrule 1.0 mm id (10/pk) 5080-8773 32. Column nut

5183-4732

1

26

1

27

28

29

30 19

*Also refer to the Agilent chemical analysis consumables and accessories catalog.

Released: DEC 2002

25

31

32

6850 Gas Chromatograph Service Procedures

3–4

Inlets and valves

Description

6850

Split/splitless inlet, continued

6850

Split/splitless inlet flow manifold

Inlets and valves

Split/splitless inlet manifold assembly kit G2630-61240

For replacement parts for any inlet flow manifold, see “Replacement parts for any inlet flow manifold” on page 3-9.

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

3–5

Part No.

Qty.

1. Screws, Torx T-20, M4 x 12 mm (Captive)

0515-2496

3

2. Top cover plate

G1543-00085

1

3. Top insulation

G1543-00100

1

4. Nut, Merlin Microseal

5182-3445

–

5. Septum, Merlin Microseal

5182-3444

–

6. Septum nut

18740-60835

1

7. Septum, 11 mm, low bleed (50/pk)

5183-4757

–

8. Top insert weldment, standard

19243-80570

1

9. Viton O-ring (12/pk)

5080-8898

1

10. Heater/sensor assembly

G1543-61540

1

11. Screw, Torx T-10, M3 x 16 mm

1390-1022

1

12. Inlet weldment

G1543-80580

1

13. Top gasket insulation (not shown) G1543-00155

1

14. Thermal block

1

Released: DEC 2002

G1543-20765

6850

Description

1 2 3 4 5

6 7 8 9

11

Inlets and valves

Purged/packed inlet

10

12

14

6850 Gas Chromatograph Service Procedures

Continued

3–6

6850

Purged packed inlet, continued 15

Part No.

Qty.

15. Bottom nut

G1543-20580

1

16. PPIP Insulation

G1543-00030

1

17. PPIP Bottom insulation

G1543-00070

1

18. Glass insert (25/pk)

5080-8732

1

19. Vespel ferrule (10/pk)

5080-8774

1

20. Tubing nut (1/4-inch brass) (10/pk) 5180-4105

1

21. 530-µm Column liner (See Consumables Catalog)

1

19244-80540

1/8-inch Column adapter (optional) 19243-80510 (not shown)

–

22. Nutwarmer insulation

19234-60715

3

23. Nutwarmer cup

19234-60700

1

5181-7458

1

Graphite ferrule 0.5 mm ID (10/pk) 5080-8853

1

Graphite ferrule 1.0 mm ID

5080-8773

1

5183-4732

1

24. Ferrules (identify by internal dia.): Solid ferrule plug (no hole)

25. Column nut

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

16

17

18 19 20

Inlets and valves

Description

21

22 23 24 25

3–7

6850

Purged packed inlet flow manifold

Inlets and valves

Purged packed inlet manifold assembly kit G2630-61245

For replacement parts for any inlet flow manifold, see “Replacement parts for any inlet flow manifold” on page 3-9.

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

3–8

Vent Fitting, O-ring assembly G2630-61720

6850

Replacement parts for any inlet flow manifold Screw, M4 x 45 mm, T-20 0515-2484

Screw, M3 ×12 mm, TorxTorx T-10 0515-1084

Back left view

Front right view

Inlets and valves

Inlet Fitting G1543-20610

1/4-inch Viton O-ring 5180-4182 (12/pk) Continued

Figure 3-1. Inlet flow manifold replacement parts (split/splitless shown)

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

3–9

6850

Replacement parts for any inlet flow manifold, continued CAUTION! The aluminum bracket is shown removed for clarity. Do NOT completely remove the bracket during valve replacement.

Aluminum bracket

Screws M3 x 20 mm, Torx T-10 0515-1319, Qty 2 Supply fitting O-rings, 5180-4181 (12/pk)

Inlets and valves

EPC Valve, Replacement kit G1531-60610 (Includes O-rings, excludes screws) Split vent on/off valve G1544-60580

Inlet split vent fitting Septum purge fitting Split/splitless inlet shown

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

3–10

6850

Fans

Inlets and valves

Injection port fan assembly G2630-61320

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

3–11

6850

Sampling valves Sample line weldment G2630-80500 Valve heated block G2630-20710 Screw 0515-0655

Inlets and valves

Washer 3050-1977 Gas or liquid sampling valve: see Table 3-1 Gas sample loop: see Table 3-1 Heater/sensor assembly G1544-61140

Gas sampling valve

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

Continued

3–12

Diaphragm (for gas or liquid valve) 0101-0760

Valve box lid G2630-00730 Valve box chassis G2630-61400

6850

Sampling valves, continued

Inlet chassis G2630-40210

Continued

Figure 3-2. Sampling valve replacement parts, continued

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

3–13

Inlets and valves

Valve inlet insert assembly G2630-61080

Item

Part No.

Liquid sampling valve, 4 port, 0.5 µL (not shown)

0101-1012

Liquid sampling valve, 4 port, 1.0 µL (not shown)

0101-1013

Gas sampling valve, 6 port

0101-1014

Sample loop, for gas sampling valve

Item

Part No.

Valve box insulation Valve box chassis insulation (order 4 part numbers)

G2630-40010 G2630-40020 G2630-40030 G2630-40080

Valve box lid insulation (order 3 part numbers)

G2630-40040 G2630-40050 G2630-40060

0.25 mL

0101-1023

0.5 mL

0101-1021

1.0 mL

0101-1020

Three-way valve

G2630-60930

2.0 mL

0101-1019

Male connector, brass

0100-2023

Male connector, SS

0100-2022

Sampling valve (not shown) Liquid line out

G2630-80650

Metering valve (for liquid sampling valve)

0101-0355

Tubing

G1205-21430

Released: DEC 2002

Three-way solenoid valve assembly (not shown)

6850 Gas Chromatograph Service Procedures

3–14

6850

Table 3-1. Sampling Valves

Inlets and valves

Sampling valves, continued

6850

Direct Valve-to-Column Connector Kit Direct-tube assembly

1/16-inch Vespel/graphite ferrules 0100-1512 320 µm column union 0100-1527

Liner tool 18900-20850

530 µm column union 0100-1515

Inlets and valves

1/8-inch to 1/16-inch reducing union, 0100-1542 Liner for 530 µm columns, 0100-1513

SS nut, 1/16-inch 0100-1511

Liner for 320 µm columns, 0100-1514

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

3–15

Fan wire connector

Injection port cooling fan

Port on side (not visible)

WARNING

6850

Replacement Procedures

Shock hazard. Before beginning, turn off the instrument and disconnect the power cord.

2. Remove the top cover. See “Lid top cover” on page 2-15.

4. Disconnect the fan wires at the connector. When reinstalling the fan, make sure to install the fan so that the fan exhaust port faces the inlet.

3. Unscrew three T-10 Torx screws and remove the fan.

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

3–16

Inlets and valves

1. Turn off the instrument and remove the power cord.

Inlet insert weldment

Large nut (part of weldment)

WARNING High temperature. The inlet may be very hot. Before beginning, turn off the inlet heated zone and allow it to cool.

Inlet insert weldment

1. Load the SERVICE method (or turn off the GC) and allow the inlet to cool. 2. Remove the top cover. See “Lid top cover” on page 2-15.

Released: DEC 2002

4. Lift the inlet insert weldment free of the inlet.

6850 Gas Chromatograph Service Procedures

3–17

6850

3. Use the inlet wrench to release the large nut, which is part of the inlet insert weldment.

Inlets and valves

Split/splitless inlet

• If a valve box is installed, you will need to remove its top cover to access the gang fitting.

6. Remove the split vent trap bracket.

6850

5. Remove the gang block fitting from the inlet flow module.

Split vent trap Split vent trap bracket

Inlet flow manifold

Inlets and valves

Gang block fitting

7. Disassemble the split vent trap. 8. Remove the inlet insert weldment and attached parts from the instrument.

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

3–18

5. Using a 1/2-inch wrench, remove the reducing nut containing the gold seal.

WARNING High temperature. The inlet and oven may be very hot. Before beginning, turn off the inlet and oven heated zones and allow them to cool.

Remove

6850

Shell weldment

6. Close the lid.

Inlets and valves

1. Load the SERVICE method (or turn off the GC) and allow the inlet and oven to cool. 2. Remove the top cover. See “Lid top cover” on page 2-15. 3. Disconnect the column from the inlet. 4. Remove the insulation cup.

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

3–19

8. Remove the inlet liner and 1/4-inch O-ring. Split vent line Liner and O-ring

6850

7. Remove the insert weldment using the inlet wrench.

9. Remove the split vent line from the inlet.

Released: DEC 2002

10. Loosen the three T-20 Torx screws that secure the inlet to the lid.

6850 Gas Chromatograph Service Procedures

Inlets and valves

Insert weldment

3–20

6850

11. Disconnect the inlet heater/sensor connector from the wiring harness.

Inlets and valves

Disconnect heater/sensor cable

12. Lift out the inlet assembly.

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

3–21

• Install a new gold seal in the reducing nut. • When done, check for leaks using the Control Module inlet leak and the inlet split vent test.

Inlets and valves

Shell weldment

Heater block

3/4-inch nut

When reinstalling the shell weldment: • Tighten the 3/4-inch nut on the base of the heater block assembly finger-tight. Released: DEC 2002

6850 Gas Chromatograph Service Procedures

6850

13. Remove the 3/4-inch nut on the bottom of the heater block assembly and slide the heater block assembly off of the shell weldment.

3–22

3. Remove the lid top cover. See “Lid top cover” on page 2-15.

Inlet assembly and flow manifold removal

4. Open the lid. Disconnect the column from the inlet. Remove the insulation cup and insulation. Remove the bottom cover plate.

High temperature. The inlet and oven may be very hot. Before beginning, turn off the inlet and oven heated zones and allow them to cool. 1. Load the SERVICE method, or turn off the inlet and oven heated zones and allow them to cool, or turn off the instrument and allow the heated zones to cool. 2. Turn off the carrier gas at its source.

Released: DEC 2002

5. Close the lid. 6. Loosen the two screws in the connector cover plate and slide the cover plate off. Then, disconnect the ribbon cable connector from the harness. Using a 7/16-inch wrench, disconnect the gas input line form the manifold. Next, remove the three mounting screws that hold the manifold in place. 7. Trace the heater/sensor cable from the inlet to the wiring harness connector. Disconnect it at the harness.

6850 Gas Chromatograph Service Procedures

3–23

Inlets and valves

WARNING

6850

Purged packed inlet service

Inlet and flow manifold installation 1. Place the bottom insulation ring in the inlet hole. 2. Align the long sides of the hole in the block insulation sleeve to be parallel to the long sides of the lid, then place the insulation in the hole. 3. Lower the inlet assembly into the block insulation sleeve. Route the manifold tubing along the side of the lid. Place the manifold assembly into its slot.

Released: DEC 2002

5. Connect the heater/sensor cable to the wiring harness.

6850

9. Lift the inlet assembly and manifold out of the lid. Remove the remaining insulation from the hole under the inlet.

4. Use a 7/16-inch wrench to install the gas inlet line to the back of the flow manifold. Secure the manifold in place with three T-20 Torx screws.

6. Connect the flow manifold ribbon cable to the wiring harness. Reinstall the connector cover plate and the two mounting screws. 7. Discard the center plug in the bottom block insulation. 8. Open the lid. Push the bottom insulation ring over the bottom of the inlet. Force it up until the bottom cover plate can rest flush with the oven top. Secure the cover plate with two screws. 9. Install the cup insulation and the cup.

6850 Gas Chromatograph Service Procedures

3–24

Inlets and valves

8. Remove the three T-20 Torx screws holding the inlet in the lid.

11. Restore carrier and other gases to the instrument.

13. Apply your normal operating pressures. Leakcheck the flow module and column fittings. 14. Check for leaks using the Control Module.

High temperature. The inlet and oven may be very hot. Before beginning, turn off the inlet and oven heated zones and allow them to cool. Shock hazard. Before beginning, turn off the instrument and disconnect the power cord. 1. Load the SERVICE method, or turn off the inlet and oven heated zones and allow them to cool, or turn off the instrument and allow the heated zones to cool. 2. Turn off the carrier gas at its source. 3. Remove the lid top cover. See “Lid top cover” on page 2-15.

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

3–25

Inlets and valves

12. Restore power.

WARNING

6850

Inlet weldment

10. Reconnect the column.

9. Lift the inlet assembly and manifold out of the lid. Remove the remaining insulation from the hole under the inlet.

5. Close the lid.

10. Unplug the heater/sensor leads from their connector to the left of the inlet. 11. Lift the inlet out of the instrument.

Inlets and valves

6. Loosen the two screws in the connector cover plate and slide the cover plate off. Then, disconnect the ribbon cable connector from the harness. Using a 7/16-inch wrench, disconnect the gas input line form the manifold. Next, remove the three mounting screws that hold the manifold in place. 7. Trace the heater/sensor cable from the inlet to the wiring harness connector. Disconnect it at the harness. 8. Remove the three T-20 Torx screws holding the inlet in the lid.

Figure 3-3. Removing the top inlet plate Released: DEC 2002

6850

4. Open the lid. Disconnect the column from the inlet. Remove the insulation cup and insulation. Remove the bottom cover plate.

6850 Gas Chromatograph Service Procedures

3–26

13. Reinstallation is the reverse of removal. When done, check for leaks using the Control Module.

Direct Valve To Column Connector Kit

Inlets and valves

Inlet weldment

Use this kit to connect your 6850 gas or liquid sampling valve directly onto a column to avoid unacceptable peak tailing. To use this kit, your 6850 GC must have a purged packed inlet.

Thermal block

Bottom nut

Figure 3-4. Removing the thermal block Released: DEC 2002

6850 Gas Chromatograph Service Procedures

6850

12. If you need to remove the thermal block, slide off the insulation sleeve and use a wrench to remove the bottom nut. Slide the thermal block off the inlet weldment.

3–27

Part No.

Quantity

Direct-tube assembly

n/a

1

SS bulkhead union, 1/16-inch to 530 µm column

0100-1515

1

SS bulkhead union, 1/16-inch to 320 µm column

0100-1527

1

Ferrule, Vespel/graphite, 1/16-inch

0100-1512

4

Liner, polyamide, for 530 µm columns

0100-1513

1

Liner, polyamide, for 320 µm columns

0100-1514

1

SS nut, 1/16-inch

0100-1511

2

1/8-inch to 1/16-inch reducing union

0100-1542

1

Liner tool

18900-20850

1

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

Inlets and valves

Description

6850

This kit contains:

3–28

6850

Disconnect the existing inject line

WARNING The oven, detector, and inlet heated zones may be very hot. Column fittings and other hardware may remain hot after the oven has cooled.

Inlets and valves

1. Turn off the GC oven, inlet, and detector heated zones and allow them to cool. 2. Turn off the GC and unplug the power cord. 3. Remove the top cover from the valve box. 4. Remove the screw and washer that hold the inject line onto the valve heated block.

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

3–29

6850 Remove screw and washer

Figure 3-5. Disconnect the inject line from the valve

Released: DEC 2002

5. Disconnect the sampling valve from the inlet at valve port 1. Cap the line to the inlet using the tube cap from the direct-tube assembly.

6850 Gas Chromatograph Service Procedures

3–30

Inlets and valves

Disconnect inject line

6850

Install the direct-to-column line 1. Open the lid and disconnect the column from the inlet. Plug the inlet column fitting with a no-hole ferrule and column nut.

Caution

Inlets and valves

Do not use the 1/16-inch direct-tube assembly supplied in this kit to punch the hole through the insulation unless the protective cap is on. If left unprotected, insulation will be trapped in the tubing! 2. Locate the small through hole in the oven lid between the purged packed inlet and the valve box. There is a corresponding hole in the bottom of the oven lid, behind the inlet. Using a spare 1/16-inch tube, a wire, or a thin screwdriver, clear the insulation from this hole. See Figure 3-6. Released: DEC 2002

6850 Gas Chromatograph Service Procedures

3–31

6850 Inlets and valves

Oven lid through hole

(Liquid sampling valve shown)

Figure 3-6. Location of oven lid through hole

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

3–32

3. Insert the direct-tube assembly through the hole in the oven. Clean off any insulation stuck to the tubing or protective cap. 4. Loosely connect the tube to the sampling valve at port 1. Tighten 1/4 turn past finger tight. Install the screw and washer (removed under “Disconnect the existing inject line” above) through the direct-tube assembly coil and secure it to the valve heated block. 5. Remove the protective cap from the valve fitting on the direct-tube assembly and install it

Released: DEC 2002

6. Remove the plastic cap from the other end of the tube.

Caution Do not use a stainless steel ferrule. Once installed, you will not be able to remove it, and you will have to cut the direct-tube assembly to change to a different diameter column. 7. Install a zero dead volume (ZDV) union onto the bare end of the direct-tube assembly using a a 1/16-inch graphite/Vespel ferrule supplied in this kit. • For 320 µm columns, install part number 0100-1527

6850 Gas Chromatograph Service Procedures

3–33

6850

When inserting the direct-to-column tube through the oven, leave the protective cap in place to prevent insulation from clogging the tubing.

Inlets and valves

onto the open end of the inject line to the inlet.

Caution

Figure 3-7. Union installed onto the directtube assembly

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

6850

• For a 1/8-inch packed column, install the 1/8-inch to 1/16-inch ZDV reducing union

Inlets and valves

• For 530 µm columns, install part number 0100-1515

3–34

10. Plug in the GC power cord. Leak test Leak test the system using an electronic leak detector (if available and if helium is used as the carrier gas) or as described below. 1. If using hydrogen as a detector gas, turn it off. 2. Make sure the pressure at the carrier gas supply is at least 35 psi.

• Capillary column: insert the end of the column into the side of a clean septum. 4. Close the oven and turn on the GC. 5. Use the Control Module or data system to define a capillary column with length 0 m and any diameter. This puts the inlet into pressure control mode. 6. Set the inlet and oven to normal operating temperatures. 7. Set the inlet pressure to 25 psi. If pressure cannot be reached, there is a gross leak. Check the column cap.

3. Disconnect the column at the detector fitting and plug the end: Released: DEC 2002

6850

9. Clean up any pieces of insulation in the oven.

• Packed column: cap the end with a clean Swagelok cap.

6850 Gas Chromatograph Service Procedures

3–35

Inlets and valves

8. Connect the column to the ZDV union using the appropriately-sized liner and the counterbored nut provided (capillary columns) or 1/8-inch nut (packed columns).

6850

8. Allow the pressure to stabilize for one minute, then turn the pressure off. Monitor the pressure for 10 minutes. • If the pressure drop is inlet pressure setpoint)

The GC method specifies a 10 meter, 530 µm internal diameter column, used in split mode. The inlet pressure needs to be set such that the helium carrier linear velocity is in the optimum range (30 to 35 cm/s).

NOTE: This pressure will be significantly higher using nitrogen carrier instead of helium!

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

6850

This test can be performed manually on the 6850 with the inlet in split mode by removing the column and capping the inlet fitting, setting the inlet pressure to 0.1 psi and the inlet total flow to 400 mL/min. The actual pressure should be about 1.1 to 1.5 psi with split liner 5183-4647 installed and about 5 to 6 psi with a splitless liner installed.

Typical example of the problem

Troubleshooting

400 mL/min and the inlet pressure to 0 psi. Actual inlet pressure is then monitored. The test passes if the actual pressure is below 1.5 psi. The example on the following pages will describe possible causes of test failure.

9–4

6850

The Agilent pressure/flow calculator is depicted below to demonstrate how the GC EPC system would setup flows and pressures for the method:

Optimum linear velocity

Troubleshooting

Split ratio of 135:1 results in a split vent flow of 396 mL/min and a total inlet flow of about 400 mL/min (column + septum purge + split vent flows)

Inlet pressure required for optimum liner velocity

The problem will be exaggerated because of the low inlet pressure required for the method. Refer Released: DEC 2002

6850 Gas Chromatograph Service Procedures

9–5

Inlet pressure setpoint: 1.5 psi

100 psi input pressure

Flow sensor

Pressure sensor

400 mL/min

5.9 psi

Total flow control loop

Septum purge regulator fixed @ 3 mL/min

3

Proportional valve 1

Split vent Split vent trap

Purge valve open Proportional valve 2

2

Reduced flow

Troubleshooting

Carrier supply total flow in

6850

to the pneumatic diagram below for illustration of the flow and pressure characteristics of the system.

4

1 Full flow split flow path

Old style split vent trap Column flow

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

9–6

13.17 mL/min column flow instead of the desired 2.93 mL/min

c. The 1/8-inch copper tube between the injection port body and the split vent trap may have condensed sample material that has accumulated after repeated injections of viscous samples

130 cm/sec. average linear velocity instead of the desired 33.3 cm/sec 2. Proportional valve 2, which functions as the inlet back-pressure regulator is set fully open by the EPC control in order to lower the inlet pressure to the setpoint of 1.5 psi. The inlet pressure cannot go down because of restriction in the split vent flow path. There are five possible sources of this restriction:

Released: DEC 2002

b. The clearance between the outside diameter of the glass liner and the inner surface of the injection port body

d. The split vent trap may be of the older, more restrictive design or may be getting plugged by condensed sample e. Proportional valve 2 could be stuck partially closed or have contamination that is partially plugging the orifice of

6850 Gas Chromatograph Service Procedures

9–7

6850

a. Insufficient clearance for flow at the interface of the glass injection port liner and the gold seal at the base of the inlet

Troubleshooting

1. The problem with the system is that the inlet pressure setpoint is 1.5 psi (see pressure/ flow calculator on the previous page). The actual inlet pressure is 5.9 psi. This results in a "Not Ready" status on the GC and significantly increased column flow and linear velocity:

1. Select an appropriate liner for the split application. Depicted below are the two inlet Deactivated Splitless Liner Part number 5062-3587

Deactivated Split Liner Part number 5183-4647 Glass wool held in place by indents to provide complete sample vaporization and to wipe the syringe needle.

900 micro liter internal volume to expansion accommodate solvent Glass wool at base to filter non-volatile sample components Larger outside diameter to limit sample exposure to injection port body during the splitless delay.

Released: DEC 2002

Glass bead at the base to provide optimum clearance for split flow with minimal restriction. Smaller outside diameter than splitless liners.

6850 Gas Chromatograph Service Procedures

9–8

6850

Suggested Solutions

liners shipped by Agilent Technologies with the 6850 GC. One is for split, the other for splitless analysis. There are very specific design differences in the two glass liners to make them optimum for their respective operating modes.

Troubleshooting

the valve (in this case, the valve or EPC module would need to be replaced)

2. Inspect and clean the split exit fitting of the injection port body and clean or replace the 1/8-inch copper tube between the split exit fitting and the split vent trap. 3. Replace the cartridge filter in the split vent trap assembly. If the trap design does not incorporate the replaceable cartridge filter, install upgrade kit part number G1544-60610.

6850

vent flow rates without developing unwanted inlet back-pressure.

Gold seal Washer

Standard gold seal 18740-20885

Troubleshooting

Liner selection for split application not only affects inlet back pressure at low operating pressures, but also split precision, linearity and boiling point discrimination. Any liner that has a restrictive design at the bottom, like a check valve, gooseneck or spiral will adversely affect chromatographic performance.

High split flow gold seal 5182-9652

4. If not using a recommended Agilent glass split injection port liner, there is an optional gold seal that accommodates higher split Released: DEC 2002

6850 Gas Chromatograph Service Procedures

9–9

6850

The high split seal should not be used with the recommended Agilent glass split liner (part number 5183-4647) or if the inlet is being used in splitless mode. After any system modifications, always perform the inlet leak test per the operator’s manual.

Cannot achieve setpoint pressure

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

Troubleshooting

The purpose of this section is to outline a logical procedure for troubleshooting a 6850 series GC that will not equilibrate to the setpoint pressure of the capillary inlet system. The inlet actual pressure stays below the setpoint (or at 0 psi) and the GC cannot become "Ready for Injection." The procedures in this document address the class of problems that are generally related to inlet leaks.

9–10

100 psi input pressure

Flow sensor

Pressure sensor

55 mL/min

20 psi

Septum purge regulator fixed @ 3 mL/min

Pressure control loop

Total flow control loop

Split vent 50 mL/min

Proportional valve 1

Gold seal

Split vent trap

Reduced flow

Purge valve open

Troubleshooting

Carrier supply total flow in

6850

Refer to this schematic of the capillary inlet for the following troubleshooting procedures:

Proportional valve 2

Full flow split flow path Column flow: 2 mL/min

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

9–11

Case 1: Actual inlet pressure stays at 0 psi

The procedures in this document will address three classes of capillary inlet leak problems:

If the inlet pressure does not increase at all check the following:

1. The inlet will not pressurize at all. Actual pressure stays at 0 psi after a pressure setpoint has been entered. This is usually due to a large leak.

1. The designated supply pressure is sufficient for the customer application:

3. The inlet pressure control appears to be functional, however due to chromatographic symptoms or reproducibility problems a small inlet leak is suspected.

Released: DEC 2002

• 20 psi > maximum inlet pressure of the method • Typically 80 to 120 psi for 100 psi modules and 120 to 170 psi for 150 psi modules 2. The carrier gas supply manifold is free of leaks and restrictions to gas flow.

6850 Gas Chromatograph Service Procedures

9–12

Troubleshooting

2. The inlet pressure rises very slowly and does not reach the setpoint pressure This is usually a moderate leak.

6850

Procedures

grooves in the seal facing up) and the retaining nut is tightened securely.

Septum

Gold seal

Liner O-ring

6850

3. The septum has been replaced and is inserted correctly.

4. The glass liner and liner O-ring are installed correctly and the liner is not cracked. The insert weldment is tightened.

6. Confirm that the column ferrule is installed correctly.

5. The gold seal and stainless steel washer are installed correctly (washer on the bottom,

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

9–13

Troubleshooting

Column ferrule

attach. If the screw is too long the fitting will not seal.

Split vent trap cartridge

O-rings

6850

7. If the split vent trap cartridge filter was replaced, confirm that both O-rings were installed correctly.

Split vent tubing

8. If the insert weldment gang fitting has been removed from the EPC module, check that the correct length screw was used to re-

Gang fitting

9. If the 1/8-inch copper split vent tubing was disconnected from the inlet, confirm that it has been re-attached without leaks. 10. The EPC module can fail in a mode where the inlet EPC valve does not open, causing this symptom.

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

9–14

Troubleshooting

Exploded split vent trap cartridge

NOTE: Check all of the parameters from Case 1 before proceeding. 1. Set the inlet to be tested to the following configuration: • Confirm that the installed column is configured correctly to the capillary inlet and that there is only one column configured to the inlet

• Confirm that the actual inlet pressure is still lagging the setpoint 2. Block the split vent exit on the top back of the GC with a septum. • If the pressure increases, the problem is most likely that proportional valve 2 in the EPC module, which controls inlet back pressure, is stuck open or electrically dysfunctional 3. Remove the insert weldment from the injection port body (large nut on the upper weldment assembly). 4. Set the inlet pressure to 0 psi.

• Split mode • Inlet pressure 25 psi Released: DEC 2002

6850 Gas Chromatograph Service Procedures

9–15

6850

Case 2: Actual inlet pressure increases slowly and does not reach the setpoint

• Split flow 400 mL/min

Troubleshooting

An electronic leak detector is very useful in isolating large leaks. Order Agilent product number 5182-9646 (120 volts) or 5182-9648 (220 volts).

6850

5. Hold a septum over the opening of the insert weldment that normally interfaces to the glass liner. See the following diagram: Insert weldment assembly

Troubleshooting

Septum

6. Set the inlet pressure to 25 psi. The inlet pressure should increase rapidly past the 25 psi setpoint and approach the line supply pressure. You will feel pressure against the septum (in this example 100 psi). The

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

9–16

100 psi input pressure Proportional valve 1

Flow sensor

Pressure sensor

mL/min

psi

Septum purge regulator fixed @ 3 mL/min

Total flow control loop

If the pressure is still low, the problem is isolated to:

• Proportional valve 1 in the inlet EPC module is defective or not being controlled correctly.

• Insufficient supply pressure/flow volume to the inlet EPC module

If the pressure quickly approaches the supply pressure, the leak is isolated to:

• Leak at the gang fitting of the EPC module

• The injection port body

• Cracked stainless steel tube on the insert weldment

• The 1/8-inch Swagelok fittings on the copper split vent tube (one at the injection port, one at the split vent filter)

• Septum may have a hole in it Released: DEC 2002

6850 Gas Chromatograph Service Procedures

9–17

Troubleshooting

Carrier supply total flow in

6850

pneumatic configuration now matches the following schematic:

• The gold seal/column fitting (if the large retaining nut that holds the heated block in place is nut fully tightened, it will limit the travel of the smaller nut that holds the gold seal, thereby creating a leak) Large retaining nut for heated block

• There could be a large internal leak in the EPC module, although this is very unlikely. Released: DEC 2002

Case 3: Chromatographic performance problems suggest a possible leak

6850

• The O-ring that seals the "split" line in the EPC gang fitting

See the test at the end of this section that uses the 6890 Leak Test Kit to isolate leaks internal to the EPC module.

This section contains procedures for two different inlet system leak tests. Non-invasive leak check The first leak test is performed without removing the customer's column, septum or liner. It is called the non-invasive leak check. This test does not prove that the inlet is absolutely leak free, but is a good first pass or remote diagnostic to see if complete inlet pressure testing is needed. 1. Confirm that the installed column is configured correctly to the capillary inlet.

6850 Gas Chromatograph Service Procedures

9–18

Troubleshooting

• The split vent trap (check fittings and O-rings inside)

Carrier supply total flow in 100 psi input pressure Proportional valve 1

Flow sensor

Pressure sensor

55 mL/min

20 psi

Septum purge regulator fixed @ 3 mL/min Pressure control loop

Total flow control loop

Split vent 50 mL/min Gold seal

Split vent trap

Reduced flow

Purge valve open

Proportional valve 2

Full flow split flow path Column flow: 2 mL/min

Released: DEC 2002

6850

3. Set the purge flow to 50 mL/min; purge time to 1.0 minutes.

4. Set the column flow to 2 mL/min. The system will try to establish the pneumatic conditions shown in the following diagram. The inlet pressure will be a function of the column dimensions and oven temp. This example shows 20 psi.

6850 Gas Chromatograph Service Procedures

9–19

Troubleshooting

2. Put the inlet into splitless mode.

matic configuration will change to that depicted below:

6850

5. Force the instrument into "Prep Run" by hitting the Prep Run key twice. The inlet pneuForward pressure control loop

Flow sensor 6 mL/min

100 psi input pressure

Total flow control loop

20 psi Pressure sensor

Proportional valve 1

Split vent 0 mL/min Gold seal

Split vent trap

Reduced flow

Purge valve closed

Troubleshooting

Carrier supply total flow in

Septum purge regulator fixed @ 3 mL/min

Proportional valve 2

Full flow split flow path Column flow: 2 mL/min

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

9–20

If there are leaks in the inlet, the total flow will be greater than expected. Since the flow sensor is a readout device only in splitless prep run, it

will measure any flow that escapes the inlet via a leak. The diagram below shows a 7-mL leak at the inlet gold seal. The total flow reads 12 mL/min which is the sum of column + septum purge and leak.

6850

If there are no leaks, the total flow will drop to the sum of the column flow + septum purge flow.

Forward pressure control loop

Flow sensor

100 psi input pressure

Total flow control loop

12 mL/min

20 psi Pressure sensor

Proportional valve 1

Split vent 0 mL/min Split vent trap

Reduced flow

Troubleshooting

Carrier supply total flow in

Septum purge regulator fixed @ 3 mL/min

7 mL/min Gold seal leak

Purge valve closed

Proportional valve 2

Full flow split flow path Column flow: 2 mL/min

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

9–21

3. Leave the customer's column configuration dimensions from his method.

The second leak test confirms that are no leaks in the inlet. Perform the complete inlet pressure test as follows:

4. Put the inlet into split mode.

1. Remove the column and cap the column fitting of the inlet. Use one of the following:

6. Set the split flow to 100 mL/min.

• No hole ferrule, part number 5181-7458 (part of the Leak Test Kit) • No hole column nut with any ferrule (part number 5020-8294) • Short piece of column installed in the inlet with a new septum inserted edgewise over the end of the column.

Released: DEC 2002

6850

Complete inlet pressure test

2. Cap the septum purge fitting with a 1/8-inch Swagelok cap (part number 5180-4124).

5. Set the inlet pressure to 25 psi.

7. Allow the inlet system to pressurize and equilibrate for about 5 minutes. 8. Set the inlet pressure to OFF. 9. Monitor the actual inlet pressure for a drop over time. It should drop < 0.5 psi for every 10 minutes.

6850 Gas Chromatograph Service Procedures

9–22

Troubleshooting

This is not an absolute test in that the flow sensor is not accurate or stable at low flows (< 20 mL/min).

6850

NOTE: The inlet pressure could actually rise during this test due to a normal leakage of carrier gas through proportional valve 1 in the EPC module. To avoid this, install an isolation valve (part number G1290-60515) in the carrier feed to the EPC module for the inlet under evaluation.

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

Troubleshooting

10. If the leak test fails, use a leak gun to identify the source of the leak. To determine if the leak is in the EPC module or the injection port, there is a test fitting that can be installed in place of the inlet gang fitting that facilitates leak testing of only the EPC module. This fitting is available in the Leak Test Kit (part number G1530-60960).

9–23

The purpose of this section is to outline a logical procedure for troubleshooting FID baseline problems, including noise, high background, drift or cycling. The 6850 FID uses a hydrogen flame to burn organic samples, resulting in increased ionization that is measured as a current in the 5 to 10^6 pA range. Normal FID background levels will be in the 5 to 20 pA range, with no sample present and the GC oven cool ( 20 pA).

• All metal, conditioned moisture trap closest to the tank (part number 5060-9084)

3. Poor flame stability due to a partially plugged or contaminated FID jet assembly.

• All glass, indicating O 2 trap closest to the GC (part number IOT-2-HP)

4. Mechanical noise due to loose or vibrating FID components (interconnect/spring, collector, etc.).

Never use traps made of plastic or that use O-ring seals.

Released: DEC 2002

5. Electronic noise due to faulty or out-of-specification components on the FID electrometer or signal board.

6850 Gas Chromatograph Service Procedures

9–25

6850

FID noise can be caused by many contributing factors, including:

Troubleshooting

• All metal plumbing manifold comprised of clean 1/8-inch copper (part number 5180-4196) or stainless steel tubing and Swagelok fittings (many times "clean" tubing from other vendors has caused high FID background). The gas delivery manifold must be leak free.

Procedure The following procedure will help determine the root cause(s) for high FID noise or background. 1. Confirm the integrity of the gas supply. Check gas purities. Leak test the plumbing manifolds. The gas supply pressures should be as documented in the 6850 Site Prep/ Installation Manual: Carrier/Makeup: 80 to 100 psi Air: ≥ 80 psi H2: ≥ 60 psi

Released: DEC 2002

If the background stays above 5 pA or is very unstable, the following components are suspect: a. The interconnect or spring could be contaminated, loose or deformed. Never touch the interconnect or spring with bare hands as this will contaminate them and cause leakage current.

6850 Gas Chromatograph Service Procedures

9–26

6850

2. Evaluate the level of leakage current in the FID. This is the amount of current flowing in the FID electrometer with the flame extinguished. The FID should be at operating temperature (300°C minimum). To perform the test, turn the FID off from the GC front panel or Control Module. Allow the FID background to stabilize: it should immediately drop to 2 to 3 pA and then slowly be moving towards 0 pA. The output on the display should also be very stable at this point, not jumping more than ±0.1 pA at a time.

Troubleshooting

NOTE: If the FID baseline has a periodic cycling component, it could be due to poor regulation and filtering of a house air compressor system, a defective tank regulator or a faulty detector EPC module.

If the leakage current test passes, proceed with the next test. 3. Eliminate the column/carrier as the source of noise (background). Remove the column from the FID and cap the fitting (an easy way to do this is to cut the column below the detector fitting and plug the end of the column extending from the FID by pushing a septum over the column edgewise). 4. Re-light the flame. Allow it to stabilize and reevaluate the noise. If the FID noise Released: DEC 2002

5. Measure the FID flows with an independent measurement device such as a bubble meter or electronic flow meter. Use the FID flow adapter (part number 19301-60660). The recommended flows for the FID are: Column or Column+Makeup: 30 mL/min H 2: Equal or > Column or Column+Makeup if using capillary column (optimum FID signal to noise performance is achieved at about a 1:1 ratio of H 2 to inert gas) Air: 400 mL/min

6850 Gas Chromatograph Service Procedures

9–27

6850

c. One of the two detector electronic assemblies (the electrometer or the FID electronics board) could be noisy

becomes acceptable, the problem could be due to contaminated carrier gas or excessive column bleed. If the problem persists, continue the procedure. Otherwise reevaluate with a known good, thin, well-conditioned, film column (an uncoated retention gap is a good troubleshooting tool to isolate column bleed problems).

Troubleshooting

b. The Teflon insulators that electrically isolate the collector or the collector itself could be contaminated. They can be cleaned in solvent or replaced.

Brass castle assembly Teflon insulators Collector

Sealing surface Partially plugged jet

Released: DEC 2002

6850

6. Perform FID maintenance per the GC operators manual.

Troubleshooting

There will be no carrier flow, because the column is disconnected and the detector fitting plugged. Measure the H 2, air and makeup gas flows independently by turning them on one at a time from the GC front panel or Control Module. They should be within ±10% of the setpoint. If the flows are significantly off, the jet could be partially plugged, there could be a leak anywhere in the FID pneumatic system, or the detector EPC module could be defective. Remember that flow measurement from a soap film bubble meter are affected by ambient pressure. Flow modules are calibrated at Standard Temperature and Pressure. For accurate readings, use a true mass flow measurement device (such as the Agilent Flow Tracker 1000). Resolve any flow control problems and retest the FID noise.

6850 Gas Chromatograph Service Procedures

9–28

• Inspect the underside of the brass castle assembly for rust or corrosion and replace if dirty • When reassembling the FID make sure that all mechanical assemblies are tight and that the interconnect spring does not get deformed. It should be oriented into the channel on the outer perimeter of the FID collector. • Plug the FID column fitting to continue with the troubleshooting procedure. 7. Re-light the flame and bakeout the detector at 350°C for an hour. Released: DEC 2002

If the noise or background is still too high, the Air, H2 and Makeup gas purity is suspect. The FID can be operated with just Air and H 2. Turn off the makeup gas and reevaluate the FID noise. If there is a significant drop in noise or background (>5 pA drop in background) then the makeup gas purity is suspect. Try replacing or installing traps in the makeup gas supply as outlined in the overview. If the problem persists then try installing/replacing moisture traps in the H 2 and Air supplies or try alternate sources for H 2 and Air. The noise could also be attributed to air flowing over the interconnect interface. In this case, install an FID interconnect cover (part number

6850 Gas Chromatograph Service Procedures

9–29

6850

• Clean or replace the FID collector and Teflon insulators (better to replace)

8. Reevaluate the FID noise and background at normal FID and GC oven operating temperature.

Troubleshooting

• Clean or replace the FID jet (better to replace)

If the problem persists after gas purity issues are addressed, there could still be a problem with the FID electrometer or FID electronics board. Replace and reevaluate.

Flameout (flame will not light) The purpose of this section is to outline a logical procedure for troubleshooting FID ignition problems, including difficulty lighting the FID, flameouts during injection and intermittent re-ignition during a run.

6850

G1531-00220) to minimize noise (see “Flame ionization detector” on page 4-4).

The FID will attempt to re-ignite if the detector background in picoamps drops below the Lit Offset value that is set in the Configure Detector menu. The Lit Offset is defined as the difference between the FID output in picoamps with the flame lit and the output with the flame off (typically the output of the FID with the flame off will be a very low value close to or equal to 0 pA.) The default Lit Offset value is 2.0 pA. Some Released: DEC 2002

6850 Gas Chromatograph Service Procedures

9–30

Troubleshooting

The 6850 FID uses a hydrogen flame to burn organic samples, resulting in increased ionization that is measured as a current (values up to the 10^6 pA range).

To determine if Lit Offset is the cause of the problem, set it to [0] and confirm that the flame stays lit for an entire run. If it does, choose a lower setting for Lit Offset that is appropriate for the specific FID background of that GC. Also the FID temperature should be maintained at least 20°C > the final oven temp of the GC analysis. The FID should never be operated at less than 300°C. This temperature will not damage columns with a maximum temperature lower than 300°C. Released: DEC 2002

The following procedure will help determine the root cause(s) for difficulty lighting the FID. 1. Insure the proper jet is installed. 2. Confirm the integrity of the gas supply. Check gas purities. Leak test the plumbing manifolds. The gas supply pressures should be as documented the 6850 Site Prep/Installation Manual: • This requires gas supply delivery pressures to be set according to the 6850 Site Prep Manual: Carrier/Makeup: 80 to 100 psi (150 psi for high pressure inlet) Air: 80 psi minimum H 2: 60 psi minimum

6850 Gas Chromatograph Service Procedures

9–31

6850

Procedure

Troubleshooting

FID's with very high purity gases and low bleed columns will have a background under 2 pA when they are actually lit. If this is the case, the Lit Offset value can be lowered in the detector configuration. If the Lit Offset is set too low, the flame may never try to re-ignite. If the flame is lit, a cold glass should show condensation if held above the FID.

4. Measure the FID flows with an independent measurement device such as a bubble meter or electronic flow meter. Use the FID flow adapter (part number 19301-60660). It is very important to measure the actual FID flow rates and not rely on the front panel reading for flows. This is because all of the detector flows are controlled in the EPC module by controlling a calibrated pressure against a known restriction built into the Released: DEC 2002

6850 Gas Chromatograph Service Procedures

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6850

3. Confirm that the FID igniter is glowing while the FID is trying to ignite. If not check the igniter electrical connection and confirm that the igniter body is screwed tightly into the FID castle assembly. If the igniter coil is open circuit or contaminated with corrosive material it must be replaced.

EPC module. If there are any restrictions in the H 2/Makeup gas flow path or any leaks in the detector gang fitting or the column fitting at the base of the FID, the actual flows will be wrong. Measurements from a soap film flow meter will be affected by atmospheric pressure - the FID EPC module is calibrated at Normal Temperature and Pressure (25°C/1 atm). For accurate measurements use a true mass flow meter like the Agilent Flow Tracker 1000. Refer to the following diagram for flow measurement and troubleshooting:

Troubleshooting

• Gas purities are 99.9995% or better (per 6850 Site Prep Manual)

EPC Module Pressure sensors

Air in

PS

Makeup in

PS

H2 in

A leak around the jet seal will result in correct H2 flow measurement, however the H2 is not going through the jet but around it. The flame will be unstable and hard to light.

Restrictors Air inlet

H2/Makeup gas inlet

PS

A leak at the column fitting will allow H2 to leak into the oven. The flame will be difficult to light or keep lit.

H2 makeup flow comes down the outside of the jet and up the center, sweeping outside of the column. Since these flows are pressure controlled, a restricted jet will reduce the H2 and makeup flows are pressure controlled, a restricted jet will reduce the H2 and makeup flows

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

9–33

Troubleshooting

Filter Proportional valves frits

6850

Partially clogged, restricted FID jet

FID gang fitting

Measure the flow rates for each gas independently: a. Cool the GC oven and turn off the inlet pressure/flow to stop the column flow. If there is any doubt as to column leaks, or you are using a wide bore column, disconnect the column and cap the FID column fitting.

c. Turn off H 2, turn on the Makeup gas and measure the actual flow rate. d. Turn on the H2 flow and measure the two gases together. The resulting actual flow should be exactly the sum of the two previous measurements. If it is lower this could indicate a leak in the column fitting at the detector base or a partially plugged jet. e. Turn off H 2 and Makeup gas flows. Turn on the Air flow and measure the actual flow rate. Table 9-1 lists reasons and solutions for low FID flow rates.

Released: DEC 2002

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6850

Carrier, packed columns: 30 to 60 mL/min Carrier + Makeup, capillary columns: 30 mL/min H2: set equal to or > the total carrier/makeup flow Air: 400 mL/min

b. Turn on H 2 only and measure the actual flow rate. It should be within 10% of setpoint.

Troubleshooting

The recommended gas flows for the 6850 FID are:

Solution

Leak at column fitting Replace column adapter, column ferrules Plugged or partially pluged jet

Clean or replace. To clean, use a .011” or .018” wire to clean the jet. Sonicate the jet in a solvent appropriate to the application.

Loose or missing gasket at base of FID

Replace

An electronic leak detector is very useful for determining if the column fitting is leaking. If a leak is suspect, replace the column ferrule and the capillary adapter fitting ferrule if installed. When reinstalling the capillary column, remember to withdraw the column 1 to 2 mm from the tip of the jet to avoid possible restriction to H 2 and makeup flow. The Control Module for the 6850 GC has a built in diagnostic to determine if the jet is plugged called the "Jet Test." If any or all of the gas Released: DEC 2002

If any of the measured flow rates are incorrect, there is always the possibility that the EPC module is out of calibration or defective.

6850

Reason

flows are low, there could also be leak(s) at the EPC gang fitting. In this case, replace the O-rings and tighten if necessary (10 mm screws, part number 0515-2495).

All of the flows could measure correctly and the FID jet seal could be leaking.

Sealing surface

If there is an imperfection in the seal, H 2 will leak around the jet rather than going through. This will make the flame very difficult to light and also very unstable (it will tend to extinguish with solvent elution through the detector).

6850 Gas Chromatograph Service Procedures

9–35

Troubleshooting

Table 9-1. Low FID flow rates

Troubleshooting

6850

Remove the jet and examine the sealing surface. There should be a continuous ring around the tapered portion of the jet. Replace if necessary.

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

9–36

The purpose of this section is to describe the causes of baseline ringing on the tail of TCD peaks and suggest operating parameters to eliminate the problem. The 6850 uses a single filament TCD. The column effluent and carrier reference gas are switched across the TCD filament at a 5 Hz rate. Due to the 5 Hz mechanical/pneumatic switching, the most narrow, gaussian peak that the TCD can be used to quantitate accurately and reproducibly is 0.02 minutes. Any peak this wide or greater should use a Chemstation sampling rate of 5 Hz. Any faster sampling adds no useful information to the peak data. Faster peaks, like Released: DEC 2002

NOTE: TCD noise should never be evaluated at a Chemstation data rate > 10 Hz.

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6850

Ringing on tail of TCD peaks

the Operational Qualification unretained, fast solvent peak (0.01 minutes wide), could benefit from 10 Hz data rate, but never 20. Theoretically system precision will start to suffer with peaks under 0.02 minutes wide mainly due to the hardware switching rate, regardless of sampling rate. The splitless, FID checkout sample peaks (C14,15,16) exhibit worse ringing on the tail because of column overload which causes a fast return to baseline, hence a higher frequency component to the signal.

Troubleshooting

Thermal Conductivity Detector

Troubleshooting

6850

Example chromatogram

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

9–38

6850

TCD response and peak shape with respect to data rate 20 Hz data rate Areas: C14 C15 C16 85.3 84.2 82.9

Areas:

5 Hz data rate C14 C15 86.3 85.5

Troubleshooting

10 Hz data rate Areas: C14 C15 C16 85.8 84.9 83.6

C16 84.1

These chromatograms were produced on 6850/TCD/PPIP - standard checkout sample

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

9–39

6850

20 Hz data rate

Troubleshooting

10 Hz data rate

5 Hz data rate

Comparison of peak shapes

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

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6850

Comparison of ringing on peak tails Tail of C14 at 20 Hz

Troubleshooting

Tail of C14 at 10 Hz

Tail of C14 at 5 Hz

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

9–41

Troubleshooting

6850

Comparison of TCD noise acquired at 20, 10 and 5 Hz

The specification for TCD noise is < .057 display units (25µV)

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

9–42

• The oven flap motor will not be positioned for initial operation

Blown fuses (dead instrument)

• The inlet cooling fan will not turn on. The 6850 will power up correctly if the following conditions are true:

The 6850 is a microprocessor based instrument. Virtually all functions of the GC are monitored and controlled by the microprocessor. If the processor is not operating properly (executing the internal program stored on the ROM), then the GC will appear to be dead. The obvious symptom of a dead GC will be no front panel display characters. There are other more subtle symptoms including: • No relays clicking as the GC goes through the Power On Self Test

Released: DEC 2002

1. The +5 VDC power supply is operational and in specification. This supply is on the mainboard. 2. Appropriate firmware (the microprocessor code that gives the GC its functionality) is installed properly on the GC main board. 3. The internal clocks for timing and synchronization of data for memory and I/O are functioning. All of these clock circuits are on the mainboard. 4. There are no shorts on the Data or Address busses by which the microprocessor

6850 Gas Chromatograph Service Procedures

9–43

Troubleshooting

The purpose of this section is to outline a logical procedure for troubleshooting a 6850 GC that is dead at turn on.

6850

Electronic Failures

6850

accesses memory and communicates with I/O devices connected to the GC main board. 5. The GC display board must be functional to be able to determine if the 6850 is powering up correctly.

Troubleshooting

NOTE: Be sure to turn off the 6850 power switch and disconnect the power cord before removing or re-installing any cable connectors or printed circuit board assemblies and while checking fuses. Observe electrostatic discharge precautions while removing or re-installing printed circuit board assemblies.

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

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Use the following figures as a guide to the troubleshooting procedure: F3 AC board

Oven fan heater and triac

F4 AC board Oven relay (controlled by µprocessor) H Line in N F1 AC board

F2 AC board AC board fuses Location Amps Part number 2110-0056 F1 6A F2 6A 2110-0056 15A 2110-0054 F3 F4 15A 2110-0054

Released: DEC 2002

Main power switch

Main power transformer

Oven flap motor Cryo valve Cooling fans AC board Internal/external valves All EPC modules

F1/F2 main board

±24 VDC unregulated

Main board surface mount fuses

40 VDC heated zone supply

F3 main board

7683 power supply

6850 Gas Chromatograph Service Procedures

Oven temperature control

µprocessor

Analog circuits +10 V ref.

Digital logic on every PC board

±15 VDC regulated

+5 VDC regulated

Inlet/detector/auxilary heaters Main board fuses Location Amps Part number 2110-0709 F1 5A F2 5A 2110-0709 F3 5A 2110-0709

9–45

Troubleshooting

6850

Power distrubution

6850

Main board connectors, test points, and fuses F1 P1

-24 V +24 V

P1

F2 F3

P2 P8

P8

-15 V +15 V

P2

P3 P9 P19

P6 P5

P4

P12

J1

P19

+5 V

P9

P6 P5

P4

J1

GND

P20

P20 J3

J3

P23

P23

P11

P17

P17 P10

P10

Released: DEC 2002

P24

P7

J2

GND

P7

J2

G2630-66015

G2630-60010 6850 Gas Chromatograph Service Procedures

9–46

Troubleshooting

P3

-24 V +24 V +15 V -15 V +5 V

Dead GC The following procedure will help determine the root cause(s) for a dead 6850 GC.

NOTE: Be careful when removing the wires from the oven interlock switch as they break easily. Also, be sure to prevent them from touching ground while troubleshooting the GC.

1. Measure the ±24 VDC unregulated power supply at the test points (P14, P15) on the main board. Set the multimeter to DC volts.

Released: DEC 2002

6850 Gas Chromatograph Service Procedures

Troubleshooting

2. Connect the voltmeter black lead to ground and the red lead to the 24 V test points on the 6850 mainboard to make the measurement. Follow the procedure for removing the electronics cover to access these test points.

6850

Procedures

9–47

Check main board fuses F1, F2

+24 VDC OK? N (±10%)

F1/F2 fuses OK?

N

Y

Y Go to “Minimum Machine:” 1. Disconnect P4/P5/P6/P19 2. Remove LAN card and P11 3. Remove any external back panel connectors

Check line power, AC board fuses F1/F2, power switch, power transformer

If GC is OK under minimum machine configuration: Replace connectors one at a time until it fails and address the source of the problem

Remove/disconnect: P20 Oven flap motor P19 Cooling fans P17 Oven fan motor P9 Main wire harness P23 Keyboard/display J2 External valves Replace F1/F2 on main board

Power on F1/F2 fuses OK?

Y

Replace GC main board

Y

1. Replace keypad/display board 2. Replace GC mainboard

Released: DEC 2002

N

Troubleshooting

Measure +24 VDC

GC still dead? N

6850

3. Use the following flow chart to determine the root cause of the problem:

Reconnect above connectors one at a time until fuses blow and replace the faulty assembly

6850 Gas Chromatograph Service Procedures

9–48

• The +24 V power supply is unregulated, and therefore relies on mainboard fuses F1 and F2 for short circuit protection. The specifications for the DC power supplies are noted in Table 9-2.

Released: DEC 2002

Supply

% tol

Rated I (Fl) System PARD V pp

+24

±10%

4.75 A