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GC3-Natural Gas Analysis Advanced User Guide
Manual Information
Author(s): | C. Bennight |
Reviewer(s): | L. Brandt, C. Neal, K. Marsaglia |
Editor(s): | K. Graber, L. Peters |
Management Approval (Name, Title, Date): | D.J. Houpt, Supervisor of Analytical Systems, 9/24/2010 |
Audience: | Research Specialists, Laboratory Technicians |
Origination date: | 5/12/2008 |
Current version: | Version 1.0 09/24/2010 |
Revised: | |
Domain: | Chemistry |
System: | Gas Chromatography |
Keywords: | Hydrocarbons, headspace gas, methane, ethane |
Changes to User Guide
Summarize requested modifications to this user guide in an e-mail and/or annotate the PDF file and e-mail change requests to techdoc@iodp.tamu.edu.
User Guide Contents
Topic | See page… |
Introduction | |
Instrument Installation & Setup | |
GC3 & NGA Startup | |
LIMS Data Upload | |
Maintenance & Troubleshooting (HP6890GC) |
Introduction
Overview
The absolute quantity of hydrocarbons combined with the potential for trapping and accumulating hydrocarbons is the primary safety risk during shipboard operations. Gas monitoring via gas chromatography (GC) analysis is a means of quanitfying the risk posed by these factors. Figure 1 depicts the safe ranges for gas concentrations (C1/C2) vs. temperature.
Figure 1. Risk Assessment for Drilling Safety (IODP).
Hydrogen sulfide (H2S) is another significant risk factor for individuals working in the area. Early detection of H2S is accomplished by emergency monitors on the drill floor, and later quantification is performed on the natural gas analyzer (NGA).
Hydrocarbon Generation
Hydrocarbon generation in sediments results from thermal decomposition (maturation) of biogenic organic matter (e.g., Tissot and Welte, 1984). C1–C4 hydrocarbons may be generated in significant quantities in sediment via two processes:
- Biogenic: biogenic hydrocarbons are typically characterized by methane. They are produced in a sulfate-free environment via the reduction of dissolved bicarbonate.
- Thermogenic: thermogenic hydrocarbons are produced in sediments in direct proportion to temperature. C5 and other heavy hydrocarbons almost always result from thermal generation of hydrogen-rich organic matter. Typically, a temperature of ~100°C or greater is required for these products to become significant.
The evolution of sedimentary biogenic organic matter under increasing burial depth and consequent temperature rise is divided into three stages:
- Diagenesis
- Catagenesis
- Metagenesis
Diagenesis
Diagenesis refers to the biological, physical, and chemical alteration of sedimentary organic matter that occurs at low temperature (<50°C) in relatively recently deposited sediments (Peters et al., 2005).
Catagenesis
Catagenesis, the principal zone of oil formation, refers to a temperature range of 50°C~150°C. Liquid and gaseous hydrocarbons together with organic compounds with heteroatoms (oxygen, sulfur, and nitrogen) are released from the kerogen (Figure 2), so the catagenesis stage is called the "oil window."
Metagenesis
The last stage of sedimentary organic matter alteration is metagenesis. Dry gases (mainly methane) are derived from liquid hydrocarbon accumulation in the crust (Figure 3). C1–C4 hydrocarbons may be generated in significant quantities in sediment via biogenic and thermogenic processes.
Figure 2. Hydrocarbon Formation Pathways in Geological Situations (Rullkotter, 1993).
Figure 3. Hydrocarbon Generation Resulting from Burial of Organic Matter during Geologic Time.
Hydrogen Sulfide
Sulfate reducing bacteria produce H2S in euxinic sediments (Raiswell and Berner, 1985). Biogenic alteration of organic matter may occur in a relatively shallow part of the sediment. Thermochemical sulfate reduction of sulfate by hydrocarbons in reservoirs occurs under high temperature (>127°C ~ 140°C) (e.g., Orr, 1974; Worden et al., 1995).
References
Orr, W.L., 1974. Changes in sulfur content and isotopic ratios of sulfur during petroleum maturation. Study of Big Horn Basin Paleozoic oils. Bull. AAPG, 58:2295-318.
Peters, K.E., Walters, C.C., and Moldowas, J.M., 2005. Origin and preservation of organic matter. The Biomarker Guide. Cambridge University Press, 3-17.
Raiswell, R., and Berner, R.A., 1985. Pyrite formation in euxinic and semi-euxinic sediments. Am. J. Sci., 285:1616-1620.
Rullkotter, J., 1993. The thermal alternation of kerogen and the formation of oil. In: Engel, M.H., and Macko, S.A. (Eds.), Organic Geochemistry. New York: Plenum Press, 377-396.
Tissot, B.P., and Welte, D.H., 1984. Petroleum Formation and Occurrence (2nd ed.), Heidelberg: Springer-Verlag.
Worden, R.H., Smalley, P.C., and Oxtoby, N.H., 1995. Gas souring by thermochemical surface reduction at 140°C. Bull. AAPG, 79:854-863.
Theory of Method
The hydrocarbon monitoring system consists of two instruments that monitor gases in core headspace and core void samples:
- GC3: Agilent 6890 gas chromatograph (GC) with a flame ionization detector (FID). This instrument measures C1–C6 hydrocarbons.
- NGA: Agilent 6890 GC with an FID and a thermal conductivity detector (TCD). This instrument measures C1–C6 hydrocarbons as well as N2, O2, CO2, CS2, and H2S gases.
GC3
The GC3 is used to determine the concentrations of the following light hydrocarbon gases:
- Methane (CH4)
- Ethene (C2H4)
- Ethane (C2H6)
- Propene (C3H6)
- Propane (C3H8)
The GC3 instrument has a 1/6-inch VALCO union injector with a 2 µm stainless steel screen and a 10 port VALCO valve that is electrically switched (Figure 4). An 80/100 mesh 8 ft HaySep "R" packed column (2.0 mm ID x 1/8 inch OD) is installed in the oven.
Figure 4. Schematic of Sample Gas Line in the GC3.
NGA
The NGA is used to determine the concentrations of nonhydrocarbon gases along with hydrocarbons from C1 to C7. The analytes measured on this instrument are:
- Nonhydrocarbons
- Nitrogen (N2)
- Oxygen (O2)
- Carbon dioxide (CO2)
- Carbon disulfide (CS2)
- Hydrogen sulfide (H2S)
- Hydrocarbons
- Methane (CH4)
- Ethene (C2H4) + Ethane (C2H6)
- Propene (C3H6) + Propane (C3H8)
- n-Butane (C4H10)
- iso-Butane (CH3–C3H7)
- n-Pentane (C5H12)
- iso-Pentane (CH3–C4H9)
- n-Hexane (C6H14)
- iso-Hexane (CH3–C5H11)
- n-Heptane (C7H16)
- iso-Heptane (CH3–C6H13)
The TCD flow path contains the following columns (Figure 5):
- 6 ft x 2.0 mm ID stainless steel column packed with Poropak T (50/80 mesh)
- 3 ft x 2.0 mm ID stainless steel column packed with molecular sieve 13x (60/80 mesh)
- 6 ft x 2.0 mm ID stainless steel column packed with 80/100 mesh HaySep R (acid wash)
The FID flow path has a 60 m x 0.25 mm ID with 0.25 µm film thickness DB-1 capillary column.
Figure 5. Schematic of a Sample Gas Line in the GC-NGA.
Instrument Installation & Setup
Agilent 6890 GC Specifications
Oven specifications | Range |
Maximum temperature | 450°C |
Temperature program | Up to 6 ramps |
Maximum run time | 999.99 min |
Temperature ramp rate | 0°–120°C/min |
Dimensions | 50 cm × 58.5 cm × 50 cm |
Weight | 112 lb (50 kg) |
Heat dissipation | 7681 BTU/hr max |
Operating temperature | 20°–27°C |
Operating humidity | 50%–60% |
Gases
The GC requires that hydrogen and air are connected to the marked fittings on the back of the instrument. The type of makeup gas must be identified in the method file.
- Air, compressed (Zero-Air +): >50 psi
- Helium, compressed (99.9995% +): >50 psi
- Hydrogen, compressed (99.9995% +): >50 psi
GC3 Method: GC390FR.M
h7.Injector
- Injection source: manual
- Injection location: front
h7.Oven
- Initial temperature: 90°C
- Maximum temp: 250°C
- Initial time: 0.50 min
- Equilibration time: 1.00 min
- Port temp: 100°C
- Post time: 0.00 min
- Run time: 8.60 min (run time will automatically be changed based on ramp setting)
Temperature program:
Ramp
Rate (°C/min)
Final Temperature (°C)
Final Time (s)
1
30.00
100
0.00
2
15.00
110
4.50
3
50.00
150
1.80
4
0.00
h7.Front Inlet- Initial temp: 120°C
- Flow: 30.6 mL/min
- Gas type: helium
h7.Column 1
- Packed column (model #: Restek PC3970)
- HaySep "R" 80/100, 2.00 mm ID x 1/8 inch OD, 6 ft
- Max temperature: 225°C
- Mode: ramped flow
- Initial flow: 30.0 mL/min
- Initial time: 2.70 min
- Post flow: 0.0 mL/min
- Inlet: front
- Outlet: front detector
- Outlet pressure: ambient
Temperature program:
Ramp
Rate (°C/min)
Final Temperature (°C)
Final Time (s)
1
100.00
40
3.00
2
10.00
30
0.30
3
100.00
60
0.00
h7.Column 2 (not installed)
h7.Front detector (FID)- Temperature: 250°C (always on)
- Hydrogen (H2) flow: 40.0 mL/min (on if FID temperature is >150°C, auto control)
- Air flow 400.0 mL/min (on if FID temperature is >150 °C, auto control)
- Mode*: constant makeup flow
- Makeup flow*: 25.0 mL/min
- Makeup gas type*: nitrogen (*Makeup flow: none; makeup gas: none)
- Flame: on (auto on when FID temperature reaches 150°C)
- Electrometer: on
- Lit offset: 1.0
h7.Back detector: no detector
h7.Signal 1
- Data rate: 5 Hz
- Type: front detector
- Save data: On
- Zero: 0.0
- Range: 0
- Fast peaks: off
- Attenuation: 0
h7.Signal 2
- Data rate: 20 Hz
- Type: front detector
- Save data: Off
- Zero: 0.0
- Range: 0
- Fast peaks: off
- Attenuation: 0
h7.Column comp 1 & 2
- Derive from front detector
h7.Auxillary pressure 3, 4, & 5
- Gas type: helium
- Initial pressure: 0.00 psi
h7.Valves
- Valve 5 switching off
h7.Post run time: 0.00 min
h7.Time table for valve control
- 0.01 min—Valve 5 on; 6.00 min—Valve 5 off
GC3 Sample Flow Schematics
Standby Mode
Green line shows helium carrier gas flow when GC3 is in standby mode.
- Inlet—injector port—V6—V7—V9—V8—column—V1—V10—FID
Figure 6. GC3 in Standby Mode.
Injection Mode
He carrier (green) and sample (red) gas flows during injection mode. Sample gas fills the 25 µL sample loop.
- Sample gas: injector—V3—V2—V5—V4—vent
- Carrier gas: Inlet—injector port—V6—V7—V9—V8—column—V1—V10—FID
Figure 7. GC3 in Injection Mode.
Run Mode
He carrier (green) and sample (red) gas flows during the sample run. When the valve is turned, helium coming from the inlet pushes the sample gas trapped in the sample loop.
- Sample gas: column—FID
- Carrier gas: V5—V2—V1—column—V8—V7—V9—V10—FID
Figure 8. GC3 in Run Mode.
NGA Method: NGA_CS.M
Injector
- Injection source: manual
- Injection location: front
Oven
- Initial temp: 50°C
- Maximum temp: 300°C
- Initial time: 2.00 min
- Equilibration time: 1.00 min
- Port temp: 50°C
- Post time: 0.00 min
- Run time: 14.80 min (run time will be changed based on ramp setting)
Temperature program:
Ramp
Rate (°C/min)
Final Temperature (°C)
Final Time (s)
1
8.00
70
0.00
2
25.00
200
5.10
3
0.00
NA
NA
Front Inlet
- Flow: 21.0 mL/min
- Gas type: helium
Back inlet
- Initial temp: 80°C
- Initial time: 0.00 min
- Cryo: off
- Cryo type: compressed air
- Pressure: 20.75 psi (On)
- Gas type: helium
Temperature program:
Ramp
Rate (°C/min)
Final Temperature (°C)
Final Time (s)
1
0.00
NA
NA
Column 1: Not installed
Column 2
- Capillary column (model #: Agilent 122-1062)
- Agilent DB-1 (dimethylpolysiloxane) 60.0 m x 0.25 mm diameter x 0.25 µm film thickness
- Max temperature: 325°C
- Mode: constant flow, 2.0 mL/min
- Inlet: back inlet
- Outlet: back detector
- Outlet pressure: ambient
Front detector (FID)
- Temperature: 250°C (always on)
- Hydrogen (H2) flow: 40.0 mL/min
- Air flow 400.0 mL/min
- Mode*: constant makeup flow
- Makeup flow*: 50.0 mL/min
- Makeup gas type*: helium
- Flame: On
- Electrometer: on
- Lit offset: 2.0
Back detector (TCD)
- Temperature: 200°C (always on)
- Reference flow: 45.0 mL/min
- Mode: constant makeup flow
- Makeup flow: 3.0 mL/min
- Makeup gas type: helium
- Filament: on
- Negative polarity: off
Signal 1
- Data rate: 5 Hz
- Type: back detector
- Save data: on
- Zero: 0.0
- Range: 0
- Fast peaks: off
- Attenuation: 0
Signal 2
- Data rate: 5 Hz
- Type: front detector
- Save data: on
- Zero: 0.0
- Range: 0
- Fast peaks: off
- Attenuation: 0
Column comp 1
- Derive from front detector
Column comp 2
- Derive from back detector
Thermal AUX 1 & 2
- Use: valve box heater
- Initial temp: 110°C
Initial time: 0.00 min
Ramp
Rate (°C/min)
Final Temperature (°C)
Final Time (s)
1
0.00
NA
NA
AUX pressure 3
- Gas type: helium
Initial time: 4.50 min
Ramp
Rate (°C/min)
Final Temperature (°C)
Final Time (s)
1
30.00
22.20
0.00
2
1.10
27.50
0.00
3
0.00
NA
NA
Aux pressure 4 & 5
- Gas type: helium
- Initial pressure: 0.00 psi
Valves (1 to 4, initial): Switching off
Valve control time program
Time (min)
Valve control
0.00
valve 1: off
valve 2: off
valve 3: off
valve 4: off
0.01
valve 4: on
0.07valve 1: on
valve 2: on
1.80
valve 3: on
1.83
valve 4: off
8.50
valve 3: off
9.10
valve 1: off
valve 2: off
NGA Sample Flow Schematics
Standby Mode
He gas flow for standby mode (green lines).- Line 1: Aux-3—V1-4—V2-5—V2-3—capillary column—V2-4—V2-1—FID
- Line 2: Aux-4—sample inlet—V1-2—V1-3—V1-6—V1-1—V3-3—V3-4—V3-1—V4-3—V4-2—V4-5—V4-4—Vent
- Line 3: Front inlet—V3-5—V3-6—HaySep R column—V3-8—V3-7—V4-9—V4-8—TCD
- Line 4: Back inlet—V4-6—V4-7—MolSieve column—V4-1—V4-10—Vent
Figure 9. NGA in Standby Mode.
Injection mode
He carrier gas (green line) and sample gas (red line) flows in the NGA in injection mode. Sample gas fills the sample loops connected to V1 (25 µL), V3 (1 cm3), and V4 (0.5 cm3). He flushes the separation columns.
He gas flow (green):
- Line 1: Aux-3—V1-4—V1-5—V2-3—V2-2—capillary column—V2-4—V2-1—FID
- Line 3: Front inlet—V3-5—V3-6—HaySep R column—V3-8—V3-7—V4-9—V4-8—TCD
- Line 4: Back inlet—V4-6—V4-7—MolSieve column—V4-1—V4-10—Vent
Sample gas flow (purge; red):
- Sample inlet—V1-2—V1-3—V1-6—V1-1—V3-3—V3-4—V3-1—V3-2—V4-3—V4-2—V4-5—V4-4—Vent
Figure 10. NGA in Injection Mode.
Run Mode at 0.01 min (open Valve V4)
He (green) and sample gas (red) flows in the NGA 0.01 min after start of run. Sample gas remains in the sample loop connected to V1 (25 µL) and V3 (1 cm3). After V4 opens, He returning from the back inlet pushes the sample gas out of the sample loop and into the molecular sieve column. Separated elements are detected by TCD.
He gas flow:
- Line 1: Aux-3—V1-4—V1-5—V2-3—V2-2—capillary column—V2-4—V2-1—FID
- Line 2: Aux-4—V1-2
- Line 3: Front inlet—V3-5—V3-6—HayeSep R column—V3-8—V3-7—V4-9—V4-10—Vent
- Line 4: Back inlet—V4-6—V4-5
Sample gas flow (purge):
- V1-2—V1-3—V1-6—V1-1—V3-3—V3-4—V3-1—V3-2—V4-3—V4-4—out
Sample gas flow with He:
- V4-5—V4-2—V4-1—MolSieve column—V4-7—V4-8—TCD
Figure 11. NGA in Run Mode: 0.01 min after starting run.
Run Mode at 0.07 min (open Valves V1 and V2)
He (green) and sample gas (red) flows in the NGA 0.07–1.79 min after start of run. Sample gas remains in the sample loop connected to V3 (1 cm3). After V1 and V2 open, He from Aux-3 pushes the sample gas out of the sample loop connected to V1 (25 µL) and into the capillary column (60 m) through V2, where it passes into the FID.
He gas flow:
- Line 1: Aux-3—V1-4
- Line 2: Aux-4—V1-2
- Line 3: Front inlet—V3-5—V3-6—HaySep R column—V3-8—V3-7—V4-9—V4-10—vent
- Line 4: Back inlet—V4-6—V4-5—V4-2—V4-1—MolSieve column—V4-7—V4-8
Sample gas flow (purge):
- V3-4—V3-1—V3-2—V4-3—V4-4—out
Sample gas flow with He:
- V4-8—TCD
- V1-3—V1-6—V1-5—V2-3—V2-4—capillary column—V2-2—V2-1—FID
- V1-1—V3-3
Figure 12. NGA in Run Mode: 0.07–1.79 min after starting run.
Run Mode at 1.80 min (open Valve V3)
He (green) and sample gas (red) flows in the NGA 1.80–1.82 min after start of run. After V3 opens, He from the front inlet pushes the sample gas out of the 1 cm3 sample loop into the HaySep column.
He gas flow:
- Line 1: Aux-3—V1-4—V1-3—V1-6—V1-5—V2-3—V2-4
- Line 2: Aux-4—V1-2—V1-1—V3-3—V3-2—V4-3—V4-4—out
- Line 3: Front inlet—V3-5—V3-4
- Line 4: Back inlet—V4-6—V4-5—V4-2—V4-1—MolSieve column—V4-7—V4-8—TCD
Sample gas flow with He:
- Capillary column—V2-2—V2-1—FID
- B3-4—V3-1—V3-8—HaySep R column—V3-6—V3-7
Figure 13. NGA in Run Mode: 1.80–1.82 min after starting run.
Run Mode at 1.83 min (close Valve V4)
He (green) and sample gas (red) flows in the NGA 1.83–8.49 min after start of run. After V4 closes, He from the back inlet flushes the molecular sieve column (backflush). Gas samples separated by the HaySep column enter the TCD through V4.
Helium gas flow:
- Line 1: Aux-3—V1-4—V1-3—V1-6—V1-5—V2-3—V2-4—capillary column—V2-2—V2-1—FID
- Line 2: Aux-4—V1-2—V1-1—V3-3—V3-2—V4-3—V4-2—V4-5—V4-4—out
- Line 3: Front inlet—V3-5—V3-4—V3-1—V3-8
Sample gas flow with He:
- HaySep R column—V3-6—V3-7—V4-9—V4-8—TCD
Backflush:
- Line 4: Back inlet—V4-6—V4-7—MolSieve column—V4-1—V4-10—vent
Figure 14. NGA in Run Mode: 1.83–8.49 min after starting run.
Run Mode at 8.50 min (close Valve V3)
He gas (green) and sample gas (red) flows in the NGA 8.50–9.09 min after start of run. After V3 closes, He from the front inlet flushes the HaySep column and the line leading to the TCD (backflush).
He gas flow:
- Line 1: Aux-3—V1-4—V1-3—V1-6—V1-5—V2-3—V2-4—capillary column—V2-2—V2-1—FID
- Line 2: Aux-4—V1-2—V1-1—V3-3—V3-4—V3-1—V3-2—V4-3—V4-2—V4-5—V4-4—out
- Line 3: Back inlet—V4-6—V4-7—MolSieve column—V4-1—V4-10—vent
Backflush:
- Line 3: Front inlet—V3-5—V3-6—HaySep R column—V3-8—V3-7—V4-9—V4-8—TCD
Figure 15. NGA in Run Mode: 8.50–9.09 min after starting run.
Run Mode at 10.0 min (close Valves V1 and V2)
He (green) and sample gas (red) flows in the NGA 9.09–10.0 min after start of run. After V1 and V2 close, He flow returns to standby mode.
He gas flow:
- Line 1: Aux-3—V1-4—V1-5—V2-3—V2-2—capillary column—V2-4—V2-1—FID
- Line 2: Aux-4—V1-2—V1-3—V1-6—V1-1—V3-3—V3-4—V3-1—V3-2—V4-3—V4-2—V4-5—V4-4—out
- Line 3: Front inlet—V3-5—V3-6—HaySep R column—V3-8—V3-7—V4-9—V4-8—TCD
- Line 4: Back inlet—V4-6—V4-7—MolSieve column—V4-1—V4-10—vent
Figure 16. NGA in Run Mode: 9.09–10.0 min after starting run.
GC3 & NGA Startup
Overview
The chromatography application ChemStation controls GC data acquisition and processing. It can be run either online or offline. Offline mode can be run without communication with the GCs, so it is useful for reintegrating or reprocessing chromatograms. Online mode requires communication with the GC.
Starting up GC3/GC-NGA and ChemStation
Start ChemStation software and load the appropriate method for the analysis (see Starting up ChemStation and GC Ovens). | |
Condition the GC (see Conditioning the GC). If the GC has been turned off for longer than a week, then bake the column for 8 hr with gas flowing (manually set the oven temperature to 175°C for GC3 or 275°C for NGA). | |
Run a calibration curve (see GC3/NGA User Guide). | |
Run a calibration verification standard (see GC3/NGA User Guide) | |
Run a test sample (see GC3/NGA User Guide) |
Starting up ChemStation and GC Ovens
Turn on the GC. WARNING: Before turning on the GC, make sure the gas lines are open. | |
Turn on the PC. | |
Click the GC3 Online or NGA Online icon to start ChemStation. The Method and Run Control window opens. At startup, ChemStation uses the method last used (shown on the main screen). In addition, the GC LCD shows the loaded settings from ChemStation. | |
To load a different method in Chemstation:
| |
The system automatically loads the new method selected in ChemStation to the appropriate GC. Oven and detector temperatures may increase immediately after a new method is loaded, and the FID will ignite when the detector temperature reaches 150°C. Sometimes, the GC beeps because the FID flame is out, especially after a long idle period. See Maintenance & Troubleshooting (HP6890GC). |
GC3 Methods
Method Title | Definition |
GC390FR.M | Standard operation method since November 2007. |
def_gc.m | Default for ChemStation. This method must be kept in the Method folder permanently. |
cbt.m | Default method for training. |
estd_ex.m | Default method for training. |
istd_ex.m | Method created onshore to make conditions for GC3. |
NGA Methods
Method title | Definition |
NGA_CS | Standard operation method since November 2007. |
NGA_308 | Method for IODP phase 1, Expedition 308. |
def_gc.m | Default for ChemStation. This method must be kept in the Method folder permanently. |
cbt.m | Default method for training. |
estd_ex.m | Default method for training. |
istd_ex.m | Method created onshore to make conditions for GC3. |
Conditioning the GC
To condition the GCs, in the Main menu click RunControl > Sample Info. | |
Fill in the following fields:
| |
Prepare laboratory air (5000 µL) and inject it into the GC when the ChemStation software shows Ready. | |
Press the Start button on the GC control panel to start the run. | |
Confirm the chromatogram on the screen shows no peaks. If peaks are present, the system contamination must be found (injector, detector, sample loop, etc.). |
LIMS Data Upload
Overview
Data is uploaded from the GC3 and NGA in one of two modes:
- Automatic mode: files are uploaded as soon as the run completes
- Manual mode: the user selects upload from the menu
Automatic Upload
Data is uploaded from the GC3 and NGA via a multi-step process:
- When the run is complete, a macro (GC3_LIMS.MAC or NGA_LIMS.MAC) is automatically called, as configured in the method file. The macro copies information from the method directory to C:\LIMS\NGA\data or C:\LIMS\GC3\data.
- An in-house program called MegaUploadaTron (MUT) monitors the data folder locations and when a file is copied in initiates the next steps of the upload process.
- The file is opened and read, and data points are uploaded to LIMS
- The data files are compressed (zipped) and uploaded as well
- LIMS analysis codes are GC3, NGAFID, and NGATCD
- After the upload to LIMS is complete, MUT moves the data files to an archive directory at C:\DATA\GC3\archive or C:\DATA\NGA\archive.
- If an upload error occurs, the files are not archived and MUT will report the error in the main window (only).
Manual Upload
If MUT is not running when the GC finishes, files will queue in the data directory for manual upload.
Maintenance & Troubleshooting (HP6890GC)
Overview
Use the Status and Info keys on the GC keypad as a first check when something goes wrong.
Leak Checking
When checking for leaks, check both parts of the system:
- External leaks: gas cylinders, gas purifiers/traps, regulator fittings, supply shutoff valves, GC supply fittings.
- GC leaks: inlets, purge vents; column connections to inlets, detectors, valves, splitters, adapters, and unions.
For safe leak-checking and flow measurement:
- Purge flowmeters with inert gas after measuring a flammable gas (such as hydrogen).
- Measure gases individually.
- Turn off detectors while measuring gas flows.
Column Size and Carrier Gas Flow Rate
Column type | Column ID | Carrier gas flow rate (mL/min) |
|
Hydrogen | Helium | ||
Packed | 1/8 inch | 30 | |
1/4 inch | 60 | ||
Capillary | 50 µm | 0.5 | 0.4 |
100 µm | 1.0 | 0.8 | |
200 µm | 2.0 | 1.6 | |
250 µm | 2.5 | 2.0 | |
320 µm | 3.2 | 2.6 | |
530 µm | 5.3 | 4.2 | |
These flow rates at normal temperature and pressure (25°C and 1 atm) are recommended for all column temperatures. |
6890GC Messages
Message | Description/Cause | Troubleshooting |
---|---|---|
Not Ready | "Not Ready" LED lights (a component of the GC is not ready to begin a run) |
|
Method Mismatch | A loaded method contains parameters that do not match the GC's current configuration
| Follow ChemStation instructions |
Warning | A serious problem exists.
| Press Status key to view explanation |
Shutdown | Shutdown occurs/numbered error message is displayed | Pop-up message briefly explains the nature of the problem |
Faults | Hardware problem requires user intervention
| Press Status button for more information |
Bad Main Board & Fatal Errors | Main board has malfunctioned; must be replaced | See |
Anchor | ||||
---|---|---|---|---|
|
Common Chromatography Problems
Problem | Cause | Troubleshooting |
---|---|---|
No peaks on chromatogram | Acquisition aborted | Confirm the method is correct |
Bad cable or connection | Check cables between GC and PC, detectors and GC | |
Leak in sample line |
| |
FID flame out | See FID flame out/will not light | |
TCD filament break | Measure TCD filament resistance (~10 ohm) | |
Column break | Check column installation | |
Retention times inconsistent | Column flow has changed |
|
FID jet contaminated | Remove jet and clean | |
Injector port temperature wrong | Check method | |
Oven temp program changed | Check method | |
Column overload | Inject less sample | |
Extra peaks on chromatogram | Contamination in system |
|
Contaminated syringe |
| |
Noisy baseline/random spiking | Leaks |
|
Contamination |
| |
Electrical problem |
|
Common Hardware Problems
Problem | Cause | Troubleshooting |
---|---|---|
FID flame out/will not light | Detector gas flow incorrect |
|
FID temperature too low | Wait 15–20 min for conditioning | |
FID flame out/will not light | Bad igniter | Remove heater/sensor assembly from the FID and measure resistance of heater and sensor. Replace ignitor if resistance is too high or too low:
|
Jet dirty or partially plugged | Remove jet and clean | |
Flame will not stay lit | Check dessicant state in the hydrogen generator | |
Oven cannot attain or maintain setpoint temperature |
| Contact service representative |
Bad Mainboard/Fatal Error Messages
Message | Comment |
Main FPGA Failure | Contact vendor representative |
Static RAM Failure | |
Boot ROM Checksum | |
ROM #2 or #3 Checksum | EEPROM 2 or 3 malfunction |
Incorrect ROM #2 or #3 | EEPROM 2 or 3 installed in wrong position |
ROM #2 or #3 wrong version | EEPROM 2 or 3 does not match other EEPROMs |
DMA FPGA Failure | Contact vendor representative |
DRAM Failure | |
Exception Vector | |
Bus Error | |
Address Error | |
Illegal Instruction | |
Divide by Zero | |
No 512Hz Interrupt |
Shutdown Messages
Message number | Message | Explanation/Troubleshooting |
---|---|---|
1 | Oven shut off |
|
2 | Oven cryo shutdown | Timeout |
3, 5 | Inlet pressure shutdown | Inlet does not reach setpoint |
4, 6 | Inlet flow shutdown | |
5, 8 | Front detector fuel gas shutdown | Gas unable to reach/maintain setpoint in time allowed |
6, 9 | Front detector air/ref shutdown | |
7, 10 | Front detector makeup shutdown | |
8, 9, 10 | Pres aux shutdown | Pneumatics aux module cannot maintain setpoint |
9 | Multiposition valve not switching |
|
10 | Can't reach setpoint of multiposition valve |
|
11, 12 | Inlet cryo shutdown | Timeout |
12, 14 | Aux cryo shutdown | |
13, 14 | Inlet heating too slowly |
|
Warning Messages
Message number | Message | Explanation/Troubleshooting |
---|---|---|
100 | Oven sensor missing | |
101, 102 | Invalid heater power | Invalid heater power for front detector, inlet, or aux 1 or 2 |
103, 104 | Signal buffer full |
|
105 | Analog out data loss | Possible data loss |
106 | Signal data loss | |
107, 108 | Detector config changed | Correct method to match hardware |
109, 110 | Inlet config changed | |
111, 112 | Column config changed | |
113, 114, 115 | Aux method changed | |
116 | Log overflow | Capacity = 50 entries |
117, 118 | Inlet calibration deleted | Returned to default calibration |
119, 120 | Detector calibration deleted | |
121 | Aux calib deleted | |
122 | Comm data overrun | Possible data loss |
123 | Comm data error | |
124 | Comm abnormal break | Check connection |
125 | Sampler data overrun | Possible data loss |
126 | Sampler data error | |
127 | Sampler abnormal break | Check connection |
128, 129 | Inlet flow calibration fail | Contact vendor representative |
130, 131 | Aux cryo disabled | Reconfigure cryo |
132–137 | Sampling end problem | Setpoint conflicts with sampling end time parameter |
Fault Messages
Message number | Message | Comments |
---|---|---|
200, 201 | Faulty pneumatics board | |
202 | Hydrogen shutdown |
|
203–207 | Signal DSP fault | |
208–211 | Out signal path test failed | |
212, 213 | Detector electrometer out of spec | |
214, 215 | Detector flame out |
|
216–219 | TCD filament open or shorted |
|
220, 221 | Thermal shutdown |
|
222–224 | Oven temperature fault | |
225–228 | Detector temperature fault | |
229–232 | Inlet temperature fault | |
233–236 | Aux temperature fault | |
237, 238 | Line interrupt fault | |
239, 240 | Mux ADC thermal shutdown | |
241 | Invalid line sense | |
242–244 | Pneu aux module invalid constants | |
245–249 | Obsolete EEPROM | |
250–254 | Wrong module | |
255–258 | Invalid module | |
259, 260 | Detector module/board mismatch | |
261 | MIO board defective | |
262, 264 | RS232 defective | |
263 | GPIB defective | |
265–269 | Invalid pids | |
270–274 | Invalid checksum | |
275–279 | Invalid constants from factory calibration | |
280–284 | I/O failure | |
285, 286 | Detector offset adjustment failed |