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Agilent Technologies 7890A Troubleshooting Manual
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Agilent Technologies 7890A Troubleshooting Manual

Agilent Technologies 7890A Troubleshooting Manual

Gas chromatograph
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Agilent 7890A
Gas Chromatograph
Troubleshooting
Agilent Technologies

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Summary of Contents for Agilent Technologies 7890A

  • Page 1 Agilent 7890A Gas Chromatograph Troubleshooting Agilent Technologies...
  • Page 2 Notices © Agilent Technologies, Inc. 2009 Warranty Safety Notices No part of this manual may be reproduced The material contained in this docu- in any form or by any means (including C A U T I O N ment is provided “as is,” and is sub-...
  • Page 3 Contents Concepts and General Tasks Concepts How to troubleshoot using this manual The [Status] key Configurable Items to Always Keep Current Column configuration Automatic Liquid Sampler configuration Gas configuration To View the Run Log, Maintenance Log, and Event Log Information to Obtain Before Calling Agilent for Service ALS and Detector Symptoms Plunger Errors Vial Mishandled by ALS...
  • Page 4 Baseline Rise During Oven Temperature Program Poor Peak Resolution Peak Tailing Peak Boiling Point or Molecular Weight Discrimination Poor For any inlet operating in split mode with any detector For any inlet operating in splitless mode with any detector Sample Decomposition in Inlet/Missing Peaks Peak Fronting Noisy Detector, Including Wander, Drift, and Baseline Spikes Noisy baseline...
  • Page 5 Flow Never Becomes Ready Oven Temperature Never Cools Down/Cools Very Slowly Oven Never Heats Up Temperature Never Becomes Ready Cannot Set a Flow or Pressure A Gas Does Not Reach Setpoint Pressure or Flow A Gas Exceeds Pressure Setpoint or Flow The Inlet Pressure or Flow Fluctuates Cannot Maintain a Pressure as Low as the Setpoint on a Split Inlet The Measured Column Flow Does Not Equal the Displayed Flow...
  • Page 6 To Measure a Detector Flow Measuring FID, TCD, uECD, and FPD flows Measuring NPD flows To Perform the GC Self-Test To Adjust the FID Lit Offset To Verify That the FID Flame Is Lit To Verify FID Ignitor Function During Ignition Sequence To Measure FID Leakage Current To Measure FID Baseline Output To Measure NPD Leakage Current...
  • Page 7 Troubleshooting...
  • Page 8 Troubleshooting...
  • Page 9 Agilent 7890A Gas Chromatograph Troubleshooting Concepts and General Tasks Concepts 10 Configurable Items to Always Keep Current 11 To View the Run Log, Maintenance Log, and Event Log 12 Information to Obtain Before Calling Agilent for Service 13 Agilent Technologies...
  • Page 10 Concepts and General Tasks Concepts This manual provides lists of symptoms and corresponding tasks to perform should you experience errors associated with GC hardware or chromatographic output, GC Not Ready messages, and other common issues. Each section describes a problem and provides a bulleted list of possible causes for you to troubleshoot.
  • Page 11 Concepts and General Tasks Configurable Items to Always Keep Current Certain configurable items in the GC must always be kept current. Failure to do so will lead to reduced sensitivity, chromatographic errors, and possible safety concerns. Column configuration Reconfigure the GC every time a column is trimmed or changed.
  • Page 12 Concepts and General Tasks To View the Run Log, Maintenance Log, and Event Log The GC maintains internal event logs, each of which holds up to 250 entries. Use these logs to troubleshoot problems, especially when a message no longer appears on the display. To access the logs, press [Logs] to toggle to the desired log.
  • Page 13 Concepts and General Tasks Information to Obtain Before Calling Agilent for Service Gather the following information before contacting Agilent for service: • Symptoms • Problem description • Hardware installed and parameters/configuration when the error occurred (sample, supply gas type, gas flow rates, detectors/inlets installed, and so forth) •...
  • Page 14 Concepts and General Tasks Troubleshooting...
  • Page 15 Agilent 7890A Gas Chromatograph Troubleshooting ALS and Detector Symptoms Plunger Errors 16 Vial Mishandled by ALS 17 Syringe Needle Bends During Injection into Inlet 18 FID Does Not Ignite 19 FPD Does Not Ignite 22 NPD Adjust Offset Process Fails 23...
  • Page 16 ALS and Detector Symptoms Plunger Errors If the ALS reports a front or back plunger error, check the following possible causes: • The syringe plunger is sticking or is not securely connected to the plunger carrier. Troubleshooting...
  • Page 17 ALS and Detector Symptoms Vial Mishandled by ALS Refer to your sampler installation manual for additional information. When you find a mishandled sample vial, do the following: • Check for folds or wrinkles in the crimp cap, especially near the neck of the sample vial. •...
  • Page 18 ALS and Detector Symptoms Syringe Needle Bends During Injection into Inlet When troubleshooting the injector, keep your hands away from WA R N I N G the syringe needle. The needle is sharp and may contain hazardous chemicals. Refer to your ALS documentation for additional information: 7683B Automatic Liquid Sampler Installation, Operation and Maintenance 7693A Automatic Liquid Sampler Installation, Operation...
  • Page 19 ALS and Detector Symptoms FID Does Not Ignite • Verify that the Lit Offset is < 2.0 pA. • Check that the FID ignitor glows during ignition sequence. (See To Verify FID Ignitor Function During Ignition Sequence.) • Check for a plugged or partially plugged jet. •...
  • Page 20 ALS and Detector Symptoms FID Ignitor Does Not Glow During Ignition Sequence Keep body parts at a safe distance from the FID chimney while WA R N I N G performing this task. If using hydrogen, the FID flame will not be visible.
  • Page 21 ALS and Detector Symptoms Corrosion in FID Collector and Ignitor Glow Plug Agilent recommends inspecting the collector and ignitor glow plug for corrosion while performing maintenance on the FID. The FID combustion process results in condensation. This condensation, combined with chlorinated solvents or samples, causes corrosion and sensitivity loss.
  • Page 22 ALS and Detector Symptoms FPD Does Not Ignite • Check that the FPD temperature is high enough for ignition (> 150 °C). • Check FPD flow rates and that they match the type of filter installed in the FPD. • Measure the actual detector flows. (See To Measure a Detector Flow.) •...
  • Page 23 ALS and Detector Symptoms NPD Adjust Offset Process Fails • Inspect the jet to see if it is clogged. • Measure the actual detector flows. (See To Measure a Detector Flow.) • Check the condition of the bead. Replace if necessary. •...
  • Page 24 ALS and Detector Symptoms Troubleshooting...
  • Page 25 Agilent 7890A Gas Chromatograph Troubleshooting Chromatographic Symptoms Retention Times Not Repeatable 26 Peak Areas Not Repeatable 27 Contamination or Carryover 28 Larger Peaks Than Expected 30 Peaks Not Displayed/No Peaks 31 Baseline Rise During Oven Temperature Program 32 Poor Peak Resolution 33...
  • Page 26 Chromatographic Symptoms Retention Times Not Repeatable • Replace the septum. • Check for leaks in the inlet, liner (as applicable), and column connection. (See “Checking for Leaks”.) • Check for sufficient carrier gas supply pressure. The pressure delivered to the GC must be at least 40 kPa (10 psi) greater than the maximum inlet pressure required at final oven temperature.
  • Page 27 Chromatographic Symptoms Peak Areas Not Repeatable Check the ALS syringe operation. (See the Troubleshooting section of the 7683B Automatic Liquid Sampler Installation, Operation and Maintenance manual and 7693A Automatic Liquid Sampler Installation, Operation and Maintenance.) • Replace the syringe. • Check for leaks in the inlet, liner (as applicable), and column connection.
  • Page 28 Chromatographic Symptoms Contamination or Carryover If your output has contamination or unexpected peaks, do the following: Isolate the source Perform a solvent blank run using a new, pure source of solvent. If the contamination disappears, the problem may be either in the sample or solvent- related. Perform a blank run (remove the syringe from the injector and start a run).
  • Page 29 Chromatographic Symptoms • Check the sample injection volume. • Install an Agilent column backflush system. Troubleshooting...
  • Page 30 Chromatographic Symptoms Larger Peaks Than Expected • Check each configured column’s dimensions against the actual column dimensions. (See “Configurable Items to Always Keep Current”.) • Check the autosampler injection volume. • Check the vial caps. • Check configured syringe size. Some syringe sizes are specified at half- capacity.
  • Page 31 Chromatographic Symptoms Peaks Not Displayed/No Peaks • If using an autosampler: • Ensure that there is sample in the vial. • Verify that the ALS plunger carriage is secured to the syringe plunger. • Check that the syringe is installed correctly and draws sample.
  • Page 32 Chromatographic Symptoms Baseline Rise During Oven Temperature Program • Inspect the column for bleed. • Check for leaks/oxygen in carrier gas supply. • Check gas supply oxygen trap indicator or date. • Make solvent blank runs to evaluate baseline without sample.
  • Page 33 Chromatographic Symptoms Poor Peak Resolution • Set column flow to optimum linear velocity. • Install and use deactivated consumable parts in the inlet (for example, a liner). • Perform column maintenance: Bake out contaminants, remove the contaminated length of column near the inlet, and reverse and bake out the column as needed.
  • Page 34 Chromatographic Symptoms Peak Tailing The figure below shows an example of tailing peaks. When troubleshooting tailing peaks, consider: • Which peaks are tailing? • Are the tailing peaks active compounds, all compounds, or are there trends (such as early eluters or late eluters)? •...
  • Page 35 Chromatographic Symptoms Peak Boiling Point or Molecular Weight Discrimination Poor If you have trouble with peak boiling point or molecular weight discrimination (inlet discrimination), do the following: • Check the inlet for contamination. Clean and change the liner if necessary. Replace all inlet consumable parts. See the Maintenance manual.
  • Page 36 Chromatographic Symptoms Sample Decomposition in Inlet/Missing Peaks • Lower the inlet temperature. • Check for air or water in the carrier gas; verify gas purity and functionality of traps. • Verify that the liner is appropriate for the sample being run.
  • Page 37 Chromatographic Symptoms Peak Fronting The figure below shows examples of the three types of peaks: symmetric, fronting, and overloaded. Symmetrical Fronting Overloaded If peak fronting or overloading occurs, try the following: • Verify that the injection volume is appropriate. • Ensure that the column is installed properly. •...
  • Page 38 Chromatographic Symptoms Noisy Detector, Including Wander, Drift, and Baseline Spikes Noise should be measured under “normal” operating conditions, with a column connected and carrier gas on. Noise typically has a high frequency component (electronic in origin) and lower frequency components that are referred to as wander and drift.
  • Page 39 Chromatographic Symptoms • To Bakeout Contaminants from the MMI Inlet • To Bakeout Contaminants from the Purged Packed Inlet • To Bakeout Contaminants from the COC Inlet • To Bakeout Contaminants from the PTV Inlet • To Bakeout Contaminants from the VI Inlet •...
  • Page 40 Chromatographic Symptoms Baseline spiking There are two types of spiking on the baseline output: cyclic and random. Figure 1 Cyclic spiking Cyclic spiking can be caused by the following: • An electric motor • Building heating/cooling system • Other electronic interferences in the lab Figure 2 Random spiking Spikes are isolated baseline disturbances, usually appearing...
  • Page 41 Chromatographic Symptoms Low Peak Area or Height (Low Sensitivity) • If using an inlet in split mode, check the split ratio. • Check for leaks. (See “Checking for Leaks”.) • Check the inlet for contamination. (See “Contamination or Carryover”.) • Check each column and verify that it was cut and installed properly at each end.
  • Page 42 Chromatographic Symptoms • Check that the correct filter is installed and is clean. • Check the flow rates. • Check the makeup gas type. Troubleshooting...
  • Page 43 Chromatographic Symptoms FID Flame Goes Out During a Run and Attempts to Reignite The following is an example chromatogram showing a flameout from a large solvent peak. 5 min After a flameout, the GC will try to ignite the flame three times.
  • Page 44 Chromatographic Symptoms FID Baseline Output Above 20 pA • Verify the purity of the carrier and detector gas supply. • Inspect the column for column bleed. • Check the gas supply trap indicators/dates and ensure that the traps are not expended. •...
  • Page 45 Chromatographic Symptoms FPD Flame Goes Out During a Run and Attempts to Reignite If the flame goes out during a run, do the following: • Check the GC system for leaks, especially at the detector column fitting. (See “Checking for Leaks”.) ≥...
  • Page 46 Chromatographic Symptoms FPD Output Too High or Too Low • Verify that the correct filter is being used. Do not use a phosphorus filter with sulfur- optimized flows or a sulfur filter with phosphorus- optimized flows. • Check the position of the column as installed in the detector.
  • Page 47 Chromatographic Symptoms FPD Low Peak Areas • Check the flow settings, then measure the actual detector flows. (See “To Measure a Detector Flow”.) • Perform complete inlet maintenance: Replace all consumable parts and bake out the inlet. • Perform column maintenance: Bake out contaminants, remove the contaminated length of column near the inlet, and reverse and bake out the column as needed.
  • Page 48 Chromatographic Symptoms FPD Large Peak Width at Half-Height If the FPD produces peaks that are abnormally wide at half the peak height, do the following: • Check the actual injection volume; reduce if necessary. • Verify that the liner is not reacting with the sample. Troubleshooting...
  • Page 49 Chromatographic Symptoms FPD Baseline Output High, > 20 pA • Check the supply gas purity. • Check all trap indicators and dates. • Check the detector for contamination. • Check for light leaks at the photomultiplier tube (PMT); tighten the PMT if it is loose. •...
  • Page 50 Chromatographic Symptoms NPD Solvent Quenching If the baseline does not recover after a solvent peak, try the following: • Turn hydrogen off/on around the solvent peak. • Use nitrogen as the makeup gas. • Set the total column flow and makeup gas to less than 10 mL/min.
  • Page 51 Chromatographic Symptoms NPD Response Low • Perform complete inlet maintenance: Replace all consumable parts and bake out the inlet. • Perform column maintenance: Bake out contaminants as needed. • A large concentration of solvent has extinguished the hydrogen/air plasma. Increase the bead voltage. •...
  • Page 52 Chromatographic Symptoms NPD Baseline Output > 8 million • The collector is shorted to the detector housing. Disassemble the collector and insulators and reinstall. Troubleshooting...
  • Page 53 Chromatographic Symptoms NPD Adjust Offset Process Not Functioning Properly • Inspect the jet to see if it is clogged. • Measure the actual detector flows. (See To Measure a Detector Flow.) • Check the condition of the bead. Replace if necessary. •...
  • Page 54 Chromatographic Symptoms NPD Low Selectivity • Verify that the hydrogen flow is correct (< 3 mL/min). • Inspect the bead; it may be defective or expended. • Verify correct bead voltage. • Replace the collector and insulators. Troubleshooting...
  • Page 55 Chromatographic Symptoms Negative Peaks Seen with TCD • Verify that the correct gas type is being used. • Check for a leak in the system, especially at the detector column fitting. (See “Checking for Leaks”.) • Consider sensitivity to analytes. •...
  • Page 56 Chromatographic Symptoms TCD Baseline Has Dampened Sinusoidal Noise Trailing Peaks (Ringing Baseline) Wrong data rate is selected in the data system. For TCD, the data rate should be < 5 Hz. Troubleshooting...
  • Page 57 Chromatographic Symptoms TCD Peaks Have Negative Dip on Tail • Check for leaks at the detector column adapter fitting. (See “Checking for Leaks”.) • Upgrade the detector to a passivated filament. Troubleshooting...
  • Page 58 Chromatographic Symptoms Troubleshooting...
  • Page 59 Agilent 7890A Gas Chromatograph Troubleshooting GC Not Ready Symptoms GC Never Becomes Ready 60 Flow Never Becomes Ready 61 Oven Temperature Never Cools Down/Cools Very Slowly 62 Oven Never Heats Up 63 Temperature Never Becomes Ready 64 Cannot Set a Flow or Pressure 65...
  • Page 60 Do this, for example: • To toggle the inlet purge valve before a splitless injection • To prepare for a pulsed injection • To turn off gas saver. For more information on [Prep Run], see the Agilent 7890A GC Advanced User Guide. Troubleshooting...
  • Page 61 GC Not Ready Symptoms Flow Never Becomes Ready If the gas flow never becomes ready, check for the following: • Check the supply gas for sufficient delivery pressure. • Check the configured gas type. The configured gas type must match the actual gas plumbed to the GC. •...
  • Page 62 GC Not Ready Symptoms Oven Temperature Never Cools Down/Cools Very Slowly If the oven does not cool down or cools down very slowly: The exhaust coming from the back of the GC is very hot. Keep WA R N I N G hands and face away from the exhaust vent.
  • Page 63 GC Not Ready Symptoms Oven Never Heats Up • Press [Status] to check for errors to report to Agilent. The exhaust coming from the back of the GC is very hot. Keep WA R N I N G hands and face away from the exhaust vent. •...
  • Page 64 GC Not Ready Symptoms Temperature Never Becomes Ready To be considered ready, a temperature must be at setpoint ±1 °C for 30 s. If a temperature never becomes ready, do the following: • Check for a missing insulation cup on an inlet or detector.
  • Page 65 GC Not Ready Symptoms Cannot Set a Flow or Pressure If you cannot set a flow or pressure using the split/splitless, MMI, PTV, VI, or cool on- column inlets, do the following: • Check the column mode. • Check that a capillary column is configured to the correct inlet.
  • Page 66 GC Not Ready Symptoms A Gas Does Not Reach Setpoint Pressure or Flow If an inlet does not reach its pressure setpoint, it will shut down in an amount of time determined by the type of inlet. Do the following: •...
  • Page 67 GC Not Ready Symptoms A Gas Exceeds Pressure Setpoint or Flow If a gas exceeds its pressure or flow setpoint, do the following: If using a split/splitless inlet, MMI inlet, PTV inlet, or volatiles interface: • Decrease the split ratio. •...
  • Page 68 GC Not Ready Symptoms The Inlet Pressure or Flow Fluctuates A fluctuation in inlet pressure causes variations in the flow rate and retention times during a run. Do the following: • Check if the gas purifier or gas generator is operating at or near capacity.
  • Page 69 GC Not Ready Symptoms Cannot Maintain a Pressure as Low as the Setpoint on a Split Inlet If the GC cannot maintain a pressure as low as the setpoint, check for the following: • Consider using a liner designed for split analysis. •...
  • Page 70 GC Not Ready Symptoms The Measured Column Flow Does Not Equal the Displayed Flow If the actual column flow does not match the calculated flow displayed on the GC, do the following: • Verify that the measured flows are corrected to 25 °C and 1 atmosphere.
  • Page 71 GC Not Ready Symptoms FID Does Not Ignite • Verify that the Lit Offset is < 2.0 pA. • Check that the FID ignitor glows during ignition sequence. (See To Verify FID Ignitor Function During Ignition Sequence.) • Check for a plugged or partially plugged jet. •...
  • Page 72 GC Not Ready Symptoms FID Ignitor Does Not Glow During Injection Sequence Keep body parts at a safe distance from the FID chimney while WA R N I N G performing this task. If using hydrogen, the FID flame will not be visible.
  • Page 73 GC Not Ready Symptoms NPD Adjust Offset Process Fails • Inspect the jet to see if it is clogged. • Measure the actual detector flows. (See To Measure a Detector Flow.) • Check the condition of the bead. Replace if necessary. •...
  • Page 74 GC Not Ready Symptoms FPD Does Not Ignite • Check that the FPD temperature is high enough for ignition (> 150 °C). • Check FPD flow rates and that they match the type of filter installed in the FPD. • Measure the actual detector flows. (See To Measure a Detector Flow.) •...
  • Page 75 Agilent 7890A Gas Chromatograph Troubleshooting Shutdown Symptoms Column Shutdowns 76 Hydrogen Shutdowns 77 Thermal Shutdowns 79 Agilent Technologies...
  • Page 76 Shutdown Symptoms Column Shutdowns The GC monitors inlet and auxiliary gas streams. If a carrier gas (which can include an auxiliary flow module or pneumatics control module) is unable to reach its flow or pressure setpoint, the GC assumes that a leak exists. It will warn you with a beep after 25 seconds, and it will continue to beep in intervals.
  • Page 77 Shutdown Symptoms Hydrogen Shutdowns Hydrogen gas may be used as a carrier or as fuel for some detectors. When mixed with air, hydrogen can form explosive mixtures. The GC monitors inlet and auxiliary gas streams. If a stream is unable to reach its flow or pressure setpoint and if that stream is configured to use hydrogen, the GC assumes that a leak exists.
  • Page 78 Shutdown Symptoms After the GC powers back on, press the key for the device that initiated the shutdown. Scroll to the pneumatic parameter that is flashing Off, then press [On] or [Off]. For example, if the front inlet ran out of carrier gas, press [Front Inlet], scroll to the pressure or flow parameter, then press [On].
  • Page 79 Shutdown Symptoms Thermal Shutdowns A thermal fault means that the oven or another heated zone is not within its allowable temperature range (lower than minimum temperature or higher than maximum temperature). To recover from this state: Fix the cause of the shutdown: •...
  • Page 80 Shutdown Symptoms Troubleshooting...
  • Page 81 Agilent 7890A Gas Chromatograph Troubleshooting GC Power On and Communication Symptoms GC Does Not Turn On 82 GC Turns On, Then Stops During Startup (During Self-Test) 83 PC Cannot Communicate with GC 84 Agilent Technologies...
  • Page 82 GC Power On and Communication Symptoms GC Does Not Turn On If the GC does not turn on: • Check the power cord. • Check the building’s power. • If the problem is at the GC, turn off the GC power. Wait 30 seconds, then turn the on the GC power.
  • Page 83 GC Power On and Communication Symptoms GC Turns On, Then Stops During Startup (During Self-Test) If the GC turns on but the normal display does not appear: Turn the GC power switch Off. Wait one minute, then turn the GC power On. If the GC does not return to normal, record any messages that appear on the display and contact Agilent for service.
  • Page 84 GC Power On and Communication Symptoms PC Cannot Communicate with GC • Run a ping test The MS- DOS ping command verifies communications across a TCP/IP connection. To use it, open the command prompt window. Type ping followed by an IP address. For example, if the IP address is 10.1.1.101, enter ping 10.1.1.101.
  • Page 85 Agilent 7890A Gas Chromatograph Troubleshooting Checking for Leaks Leak Check Tips 86 To Check for External Leaks 87 To Check for GC Leaks 89 Leaks in Capillary Flow Fittings 90 Agilent Technologies...
  • Page 86 Checking for Leaks Leak Check Tips When checking for leaks, consider the system in two parts: external leak points and GC leak points. • External leak points include the gas cylinder (or gas purifier), regulator and its fittings, supply shutoff valves, and connections to the GC supply fittings.
  • Page 87 Checking for Leaks To Check for External Leaks Check for leaks at these connections: • Gas supply bulkhead fittings • Gas cylinder fitting • Regulator fittings • Traps • Shut- off valves • T- fittings Perform a pressure drop test. Turn off the GC.
  • Page 88 Checking for Leaks Fully turn the regulator knob counterclockwise to shut the valve. Wait 5 min. If there is a measurable drop in pressure, there is a leak in the external connections. No drop in pressure indicates that the external connections are not leaking.
  • Page 89 Checking for Leaks To Check for GC Leaks Check for leaks at these connections: • Inlet septum, septum head, liner, split vent trap, split vent trap line, and purge vent fittings • Column connections to inlets, detectors, valves, splitters, and unions •...
  • Page 90 Checking for Leaks Leaks in Capillary Flow Fittings For capillary flow fittings, a leak usually indicates that the fitting has been overtightened. Unless the fitting is obviously loose, do not tighten it further. Instead, remove the connection, trim the column end, and install it again. (See To Attach a Capillary Column Using SilTite Metal Fittings.) Also inspect the plate and connection for a broken column tip.
  • Page 91 Agilent 7890A Gas Chromatograph Troubleshooting Troubleshooting Tasks To Measure a Column Flow 92 To Measure a Split Vent or Septum Purge Flow 96 To Measure a Detector Flow 98 To Perform the GC Self-Test 102 To Adjust the FID Lit Offset 103...
  • Page 92 Troubleshooting Tasks To Measure a Column Flow Measuring FID, TCD, uECD, and FPD column flow The following procedure can be used to measure column flow with an FID, TCD, uECD, and FPD. Hydrogen (H ) is flammable and is an explosion hazard when WA R N I N G mixed with air in an enclosed space (for example, a flow meter).
  • Page 93 Troubleshooting Tasks For the FPD, remove the plastic tubing from the FPD exhaust and connect the flowmeter directly to the FPD vent tube. If necessary, use a 1/4- inch tube adapter between the detector exhaust and the flowmeter tubing. Connect the flowmeter to the flowmeter adapter to measure flow rates.
  • Page 94 Troubleshooting Tasks Measuring NPD column flow Gather the following: • NPD flowmeter adapter tool (G1534- 60640) • Flow- measuring insert (19301- 60660) • Electronic flowmeter calibrated for the gas and flow rates of concern Set the bead voltage to 0.0 V. Cool the NPD to 100 °C.
  • Page 95 Troubleshooting Tasks Place the flowmeter tubing over the flow- measuring insert to begin measuring flows. Troubleshooting...
  • Page 96 Troubleshooting Tasks To Measure a Split Vent or Septum Purge Flow Hydrogen (H ) is flammable and is an explosion hazard when WA R N I N G mixed with air in an enclosed space (for example, a flow meter). Purge flowmeters with inert gas as needed.
  • Page 97 Troubleshooting Tasks • The split vent has a 1/8- in Swagelok threaded fitting. Create and use a 1/8- in tube adapter (as shown below) to convert the 1/8- in threaded fitting into a 1/8- in tube. This prevents the rubber flowmeter tubing from leaking around the threads, which will result in leakage and thus an incorrect flow reading.
  • Page 98 Troubleshooting Tasks To Measure a Detector Flow Measuring FID, TCD, uECD, and FPD flows Hydrogen (H ) is flammable and is an explosion hazard when WA R N I N G mixed with air in an enclosed space (for example, a flow meter). Purge flowmeters with inert gas as needed.
  • Page 99 Troubleshooting Tasks For the FPD, remove the plastic tubing from the FPD exhaust and connect the flowmeter directly to the FPD vent tube. If necessary, use a 1/4- inch tube adapter between the detector exhaust and the flowmeter tubing. Connect the flowmeter to the flowmeter adapter. Measure the actual flow rate of each gas one at a time.
  • Page 100 Troubleshooting Tasks Measuring NPD flows Gather the following: • NPD flowmeter adapter tool (G1534- 60640) • Flow- measuring insert (19301- 60660) • Electronic flowmeter calibrated for the gas and flow rates of concern Set the bead voltage to 0.0 V. Cool the NPD to 100 °C.
  • Page 101 Troubleshooting Tasks Place the flowmeter tubing over the flow- measuring insert to begin measuring flows. Troubleshooting...
  • Page 102 Troubleshooting Tasks To Perform the GC Self-Test Turn the GC off. Wait 1 min, then turn the GC back on. If the main GC status screen appears, the GC has passed the self- test. Troubleshooting...
  • Page 103 Troubleshooting Tasks To Adjust the FID Lit Offset To adjust the FID Lit offset: Press [Config]. Scroll to Front detector or Back detector (wherever the detector is installed) and press [Enter]. Scroll to Lit offset. With the Lit offset line highlighted, enter the new parameter for the detector and press [Enter].
  • Page 104 Troubleshooting Tasks To Verify That the FID Flame Is Lit To verify that the FID flame is lit, hold a mirror or other reflective surface over the collector exhaust. Steady condensation indicates that the flame is lit. Typically the FID output will be between 5.0 and 20.0 pA when lit and <...
  • Page 105 Troubleshooting Tasks To Verify FID Ignitor Function During Ignition Sequence Keep body parts at a safe distance from the FID chimney while WA R N I N G performing this task. If using hydrogen, the FID flame will not be visible.
  • Page 106 Troubleshooting Tasks To Measure FID Leakage Current Load the analytical method. • Make sure flows are acceptable for ignition. • Heat the detector to operating temperature or to 300 °C. Turn off the FID flame. Verify that the FID electrometer is on. Press [Front Det] or [Back Det], then scroll to Output.
  • Page 107 Troubleshooting Tasks To Measure FID Baseline Output With the column installed, load your checkout method. Set the oven temperature to 35 °C. Press [Front Det] or [Back Det], then scroll to Output. When the flame is lit and the GC is ready, verify that the output is stable and <...
  • Page 108 Troubleshooting Tasks To Measure NPD Leakage Current Load the analytical method. Set the NPD Adjust Offset to Off and the Bead Voltage to 0.00 V. • Leave the NPD at operating temperature. • Leave flows on or off. Press [Front Det] or [Back Det], then scroll to Output. Verify that the output (leakage current) is stable and <...
  • Page 109 Troubleshooting Tasks To Verify That the NPD Bead Is Ignited Hot exhaust! Detector exhaust is hot and can cause burns. WA R N I N G To verify that the bead is ignited, look through the vent hole on the detector lid to see if the bead is glowing orange. The NPD output is selected by the operator as part of the adjust offset process and generally is between 5.0 and 50.0 Troubleshooting...
  • Page 110 Troubleshooting Tasks To Verify That the FPD Flame Is Lit To verify that the FPD flame is lit: Remove the rubber drip tube from the detector vent. Hold a mirror or shiny surface near the aluminum exhaust tube. Steady condensation means that the flame is lit.
  • Page 111 Troubleshooting Tasks To Adjust the FPD Lit Offset To adjust the FPD Lit offset: Press [Config]. Scroll to Front detector or Back detector (wherever the detector is installed) and press [Enter]. Scroll to Lit offset. With the Lit offset line highlighted, enter the new parameter for the FPD (typical value is 2.0 pA), and press [Enter].
  • Page 112 Troubleshooting Tasks Troubleshooting...