Page 1 Agilent 7890 Series Gas Chromatograph Troubleshooting Agilent Technologies...
Page 2 A CAUTION notice denotes a hazard. It without prior agreement and written permitted by applicable law, Agilent calls attention to an operating consent from Agilent Technologies, Inc. as disclaims all warranties, either express procedure, practice, or the like that, if governed by United States and...
Page 3: Table Of Contents
FID Fails Leakage Current Test Possible causes Procedure NPD Fails Leakage Current Test FID Fails Baseline Test To Resolve Low Sensitivity with an FID FID Does Not Ignite FID Ignitor Does Not Glow During Ignition Sequence Agilent 7890 Series Troubleshooting...
Page 4 Sample Decomposition in Inlet/Missing Peaks Peak Fronting Noisy Detector, Including Wander, Drift, and Baseline Spikes Noisy baseline Baseline wander and drift Baseline spiking Microcell Electron Capture Detector (uECD) Noise and Sensitivity Display signal evaluation Sensitivity Contamination (high baseline) Agilent 7890 Series Troubleshooting...
Page 5 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 Agilent 7890 Series Troubleshooting...
Page 6 GC Power On and Communication Symptoms GC Does Not Turn On PC Cannot Communicate with GC GC Cannot Communicate with a Configured MS or HS GC Does Not Recover After Firmware Update GC Turns On, Then Stops During Startup (During Self-Test) Agilent 7890 Series Troubleshooting...
Page 7 To Correct Leaks in the PTV Inlet To Perform a VI Pressure Decay Test To Perform a VI Pressure Decay Test To Prepare the VI for a Closed System Leak Check To Correct Leaks in the Volatiles Interface Agilent 7890 Series Troubleshooting...
Page 8 To Verify That the NPD Bead Is Ignited To Verify That the FPD Flame Is Lit To Adjust the FPD Lit Offset When to Change Gas Purifiers To Ignore a Device’s Readiness State To Use the Stopwatch Agilent 7890 Series Troubleshooting...
Page 9 Agilent 7890 Series Gas Chromatograph Troubleshooting Concepts and General Tasks Concepts Systems Configured for Enhanced Communications Configurable Items to Always Keep Current To View the Run Log, Maintenance Log, and Event Log Information to Obtain Before Calling Agilent for Service...
Page 10: Concepts And General Tasks
This manual also includes common troubleshooting tasks as well as information needed prior to calling Agilent for service. While this manual describes troubleshooting for 7890 Series GCs in general, when describing GC keyboard usage and firmware features, this manual assumes a 7890B GC using firmware B.02.01.
Page 11: Error Conditions
Concepts and General Tasks Error conditions If a problem occurs, a status message appears. If the message indicates broken hardware, more information may be available. Press the applicable component key (for example, [Front Det], [Oven], or [Front Inlet]). Agilent 7890 Series Troubleshooting...
Page 12: Systems Configured For Enhanced Communications
Because of this interaction, always check the displays on all instruments and in the data system to learn the complete system status. In general, the GC display will present configured instrument status messages as well as its own messages. Agilent 7890 Series Troubleshooting...
Page 13: Configurable Items To Always Keep Current
The GC relies on this information to calculate flows. Not updating the GC after altering a column causes incorrect flows, changed or incorrect split ratios, retention time changes, and peak shifts. Agilent 7890 Series Troubleshooting...
Page 14: Automatic Liquid Sampler Configuration
To confirm the gas configuration: Press [Config]. Scroll to the appropriate detector or column item on the display and press [Enter] to see the type of gas configured. Agilent 7890 Series Troubleshooting...
Page 15: To View The Run Log, Maintenance Log, And Event Log
The event log records events such as shutdowns, warnings, faults, and GC state changes (start run, stop run, and so forth) that occur during GC operation. When the event log is full, the GC overwrites entries, beginning with the oldest. Agilent 7890 Series Troubleshooting...
Page 16: Information To Obtain Before Calling Agilent For Service
GC to the left of the GC power cable) • Oven configuration (fast- or slow-heating) • Press the [Status] key to display previous Error, Not Ready, and Shutdown messages. To obtain service/support contact numbers, see the Agilent Web site at www.agilent.com/chem. Agilent 7890 Series Troubleshooting...
Page 17: Als And Detector Symptoms
Agilent 7890 Series Gas Chromatograph Troubleshooting ALS and Detector Symptoms Plunger Errors Vial Mishandled by ALS (7693A) Alignment Light on 7693A/7650A Injector Tower is On Vial Mishandled by ALS (7683) Alignment Light on 7683B Injector Tower is On Syringe Needle Bends During Injection into Inlet...
Page 18: Plunger Errors
Replace the syringe if necessary (7693A, 7650A, 7683). Check the viscosity of the sample against the viscosity parameter. Reset the viscosity parameter if necessary. Restart the sequence. If the error occurs again, obtain Agilent service. Agilent 7890 Series Troubleshooting...
Page 19: Vial Mishandled By Als (7693A)
Verify that the labels do not interfere with the gripper. Vials are available with a write-on spot for easy marking. If you choose to make and apply your own labels, Agilent Technologies recommends the positioning and maximum label thickness shown in the figure below. Agilent 7890 Series Troubleshooting...
Page 20 13.4 minimum 16.4 ± 0.5 No label or tape Label skew 12.56 Maximum width measured at overlap • Check that the tray vial racks are clean and snapped into the tray base. • Calibrate the system. Agilent 7890 Series Troubleshooting...
Page 21: Alignment Light On 7693A/7650A Injector Tower Is On
If the Align Mode light is on, first verify that the turret is properly installed. Then, perform the alignment procedure as described in the 7693A Automatic Liquid Sampler Installation, Operation and Maintenance manual or the 7650A Automatic Liquid Sampler Installation, Operation and Maintenance manual. Agilent 7890 Series Troubleshooting...
Page 22: Vial Mishandled By Als (7683)
These dimensions do not make up a complete set of specifications. 5 minimum 6.25 ± 0.25 8.2 ± 0.2 34.5 32 ± 0.5 maximum 11.7 ± 0.2 Microvial insert Crimp cap sample vial Maximum height of a capped vial All dimensions in millimeters Agilent 7890 Series Troubleshooting...
Page 23 For 7683B, adjust the gripper height as follows: Press [Config]. Scroll to and select Sample tray. Scroll to Front injector offset and press [Mode/Type]. Scroll to the desired adjustment (Clock, Counterclock, or Default) and press [Enter]. Agilent 7890 Series Troubleshooting...
Page 24: Alignment Light On 7683B Injector Tower Is On
If it is missing stops, send the injector to Agilent for repair. When the alignment is complete, the Ready light turns on and the sampler returns to the ready state. Install the needle support assembly and syringe. Agilent 7890 Series Troubleshooting...
Page 25: Syringe Needle Bends During Injection Into Inlet
126.5 mm. • Check that the sample vial dimensions meet specification. “Vial Mishandled by ALS (7693A)” “Vial Mishandled by (7683)”. • Check that the crimp cap is properly installed. Refer to your sampler documentation. Agilent 7890 Series Troubleshooting...
Page 26: Fid Fails Leakage Current Test
Make sure that the interconnect spring is not damaged, bent, or dirty. The interconnect spring should be touching the bottom of the collector. If the inteconnect spring is damaged, bent, or dirty, call Agilent for service. FID interconnect spring Agilent 7890 Series Troubleshooting...
Page 27: Npd Fails Leakage Current Test
If the inteconnect spring is damaged, bent, or dirty, call Agilent for service. Correct If the interconnect spring is not damaged or dirty, and the detector output signal is still high, contact Agilent for service. Agilent 7890 Series Troubleshooting...
Page 28: Fid Fails Baseline Test
If you have just performed maintenance on the FID, first verify that the detector was reassembled properly before troubleshooting detector problems. If the FID fails the baseline test: • Ensure the purity and quality of the gas. • Replace dirty/expended chemical traps. • Bakeout the detector. Agilent 7890 Series Troubleshooting...
Page 29: To Resolve Low Sensitivity With An Fid
ALS and Detector Symptoms To Resolve Low Sensitivity with an FID “To Resolve Low Sensitivity with an FID”. Agilent 7890 Series Troubleshooting...
Page 30: Fid Does Not Ignite
• Check the column flow rate. (See To Measure a Column Flow.) Hydrogen flow should be greater than the sum of the column flow and makeup flow. • If the analysis permits, substitute nitrogen for helium as makeup. Agilent 7890 Series Troubleshooting...
Page 31: Fid Ignitor Does Not Glow During Ignition Sequence
• The ignitor is not making a good connection to the ground: • The ignitor must be tightly screwed into the FID castle assembly. • The three T-20 Torx screws that hold the collector assembly in place must be tight. Agilent 7890 Series Troubleshooting...
Page 32 ALS and Detector Symptoms • The brass knurled nut that holds the FID castle assembly in place must be tight. Perform FID maintenance if these parts are corroded or oxidized. T-20 Torx screws (3) Ignitor Knurled nut Agilent 7890 Series Troubleshooting...
Page 33: Corrosion In Fid Collector And Ignitor Glow Plug
FID. The FID combustion process results in condensation. This condensation, combined with chlorinated solvents or samples, causes corrosion and sensitivity loss. To avoid corrosion, keep the detector temperature above 300 °C. Agilent 7890 Series Troubleshooting...
Page 34: Fpd Does Not Ignite
• Measure the actual detector flows. (See To Measure a Detector Flow.) • The column may be installed too high into the detector. • Check that the FPD ignitor operates. (See To Verify That the FPD Flame Is Lit.) Agilent 7890 Series Troubleshooting...
Page 35 FPD ). Try changing to the phosphorus mode flows, lighting the flame, and gradually alter the flows to the sulfur values. • Check cable connections to coupling, coupling connection to glow plug, tight glow plug. Agilent 7890 Series Troubleshooting...
Page 36: Npd Adjust Offset Process Fails
• If the process still fails, there could be a large leak in the system. This causes measured flow rates to be different from actual flow rates. Thoroughly leak check the whole system, especially the detector column fitting. (See Checking for Leaks.) • Set the equilibration time to 0.0. Agilent 7890 Series Troubleshooting...
Page 37: Npd Bead Will Not Ignite
To Check for a Plugged NPD Jet.) • Measure the actual detector flows. (See To Measure a Detector Flow.) If the hydrogen or makeup flows are zero or much lower than the displayed flow, suspect a plugged jet. Agilent 7890 Series Troubleshooting...
Page 38: Fpd + Temperature Will Not Become Ready
(165 °C). • Check the transfer line temperature. If the transfer line is set to a very high temperature (near 400 °C), set the emission block temperature to at least 150 °C. Agilent 7890 Series Troubleshooting...
Page 39: Blinking Not Ready Light: Detector Hardware Fault/Tcd Filament Voltage
Contact Agilent for service. To continue to use the GC without the TCD: Turn off all TCD parameters. Save the method. Reconfigure the GC to use another detector. Move the column and set other parameters as needed. Agilent 7890 Series Troubleshooting...
Page 40: Shutdown (Defective) Device
Be sure to return a broken device to Ignore Ready = False after it is repaired. Otherwise, its state (temperature, flow, pressure, and so forth) will continue to be ignored, even if using this device in the analysis. To consider a device’s readiness, set Ignore Ready to False. Agilent 7890 Series Troubleshooting...
Page 41: Chromatographic Symptoms
Agilent 7890 Series Gas Chromatograph Troubleshooting Chromatographic Symptoms Retention Times Not Repeatable Peak Areas Not Repeatable Contamination or Carryover Larger Peaks Than Expected Peaks Not Displayed/No Peaks Baseline Rise During Oven Temperature Program Poor Peak Resolution Peak Tailing Peak Boiling Point or Molecular Weight Discrimination Poor...
Page 42: Retention Times Not Repeatable
• To Replace an FID Jet • To Check for a Plugged FID Jet • To Maintain the NPD Collector, Ceramic Insulators, and • To Check for a Plugged NPD Jet Agilent 7890 Series Troubleshooting...
Page 43: Peak Areas Not Repeatable
• To Perform a SS Split Vent Restriction Test. • To troubleshoot small leaks in a multimode or split/splitless inlet, see To Check for Leaks in a Split/Splitless Inlet Check for Leaks in a Multimode Inlet. Agilent 7890 Series Troubleshooting...
Page 44: Contamination Or Carryover
3 mL/min to keep the septum clean. For COC inlets, set the septum purge flow to at least 15 mL/min. Measure the flow. See “To Measure a Column Flow””. • Check all gas trap indicators and dates. Agilent 7890 Series Troubleshooting...
Page 45 • If you suspect that there is contamination in the column, perform the bakeout procedure. • Verify that the oven program temperature and time are sufficient for the samples being injected. Ghost peaks that are broader than adjacent sample peaks could be from a previous run. Agilent 7890 Series Troubleshooting...
Page 46 • If you suspect that there is contamination in the detector, perform the bakeout procedure (FID, TCD, uECD). • Verify the operation of the detectors. Replace the contaminated detector parts. • To Maintain the NPD Collector, Ceramic Insulators, and • Maintaining the FID Agilent 7890 Series Troubleshooting...
Page 47: Larger Peaks Than Expected
• Check configured syringe size. Some syringe sizes are specified at half-capacity. If the maximum syringe volume is marked at half-height on the barrel, not at the top of the barrel, enter twice the labeled volume when configuring the syringe size. Agilent 7890 Series Troubleshooting...
Page 48: Peaks Not Displayed/No Peaks
For 7683B ALS, use the tray quadrants to warm the sample. For 7693A ALS, use the vial heater (accessory G4514A Bar Code Reader/Mixer/Heater) to warm the sample vial. If the problem is with the detector, see Table Agilent 7890 Series Troubleshooting...
Page 49 Verify that the flame is still lit. • Verify that the filament is turned on. • Ensure that the reference gas is not set to zero. (The filament will not turn on with zero reference gas flow.) Agilent 7890 Series Troubleshooting...
Page 50: Baseline Rise During Oven Temperature Program
• Consider the effect of column film thickness on bleed. Try using a column with a thinner film. • Check for leaks at the column fittings. (See “Checking for Leaks”.) • Prepare and use a column compensation profile. Agilent 7890 Series Troubleshooting...
Page 51: Poor Peak Resolution
• Perform column maintenance: Bake out contaminants, remove the contaminated length of column near the inlet, reverse and bake out the column as needed. • Check column installation at both ends. • Select a higher resolution column. Agilent 7890 Series Troubleshooting...
Page 52: Peak Tailing
Check for inlet contamination. Tailing will sometimes increase with compound retention. Clean the inlet and replace contaminated inlet parts. (See the 7890 Series Maintenance manual.) • Consider the column stationary phase (active column). This only affects active compounds. An active column usually produces tailing that increases with retention time.
Page 53: Npd Peak Tailing
If you are analyzing phosphorus, install a black bead. White beads can cause peak tailing when phosphorus is being analyzed. • Verify that the correct is installed. Use an extended jet. • Replace the ceramic insulators. Agilent 7890 Series Troubleshooting...
Page 54: Peak Boiling Point Or Molecular Weight Discrimination Poor
• Check column cut and installation into the inlet. See the topic for the SS, MMI, PTV, and VI. • Check that the solvent vapor volume does not exceed the liner capacity. • Check for appropriate purge delay time. (Liner volume/column flow) Agilent 7890 Series Troubleshooting...
Page 55: Sample Decomposition In Inlet/Missing Peaks
• To Clean the COC Inlet • To Clean the Septumless Head on the PTV Inlet • To Clean the Septum Seat in the Septum Head Assembly of the PTV Inlet • To Clean the VI Agilent 7890 Series Troubleshooting...
Page 56: Peak Fronting
Change the solvent. • Use a retention gap. • Check purity of sample solvent. For solvents with large differences in polarity or boiling points, a mixed sample solvent can cause peak fronting. Change the sample solvent. Agilent 7890 Series Troubleshooting...
Page 57: Noisy Detector, Including Wander, Drift, And Baseline Spikes
• For all detectors, check for leaks at the column fittings. (See “Checking for Leaks”.) • For the FID, see To Isolate the Cause of FID Noise.  • For the TCD, verify data collection at 5 Hz. Agilent 7890 Series Troubleshooting...
Page 58 If noise increases gradually to an unacceptable level, check the following possible causes: • Bakeout the detector (FID, TCD, uECD). • Inspect the detector for contamination. Replace parts as needed. (See the 7890 Series Maintenance manual.) Agilent 7890 Series Troubleshooting...
Page 59: Baseline Wander And Drift
If the system has not stabilized at the new conditions before it starts a run, some baseline changes are to be expected. The following cases assume that sufficient stabilization time has elapsed since the last change in operating conditions. Agilent 7890 Series Troubleshooting...
Page 60: Baseline Spiking
Spiking will not normally be noticed on the display; it will be noticed only on a plot or online trace. Figure 1 Cyclic spiking Cyclic spiking can be caused by the following: • An electric motor • Building heating/cooling system Agilent 7890 Series Troubleshooting...
Page 61 If it touches a glass wool plug, spikes are produced. • Check for the correct jet. See the following: • Selecting an FID jet • To replace an FID jet • Selecting an NPD jet • To Maintain the NPD Collector, Ceramic Insulators, and Agilent 7890 Series Troubleshooting...
Page 62 • Check that the detector temperature is not too low. See the following: • Recommended starting conditions for new FID methods • Selecting reference and makeup flows for the TCD • Recommended starting conditions for new uECD methods Agilent 7890 Series Troubleshooting...
Page 63: Microcell Electron Capture Detector (Uecd) Noise And Sensitivity
The first consideration is the signal value when the GC is in the idle state. The “idle” signal level is a function of the type and quality of the carrier and detector gases, as well as the flows Agilent 7890 Series Troubleshooting...
Page 64 24 hours) before running the frequency test. If you will be injecting into an unused inlet, you must use low-bleed septa. Make sure to condition new septa before use in an inlet for several hours with 1 to 5 mL/min carrier flow. Agilent 7890 Series Troubleshooting...
Page 65: Sensitivity
If using split mode, verify the split flow using a flow meter. Check all flow rates. See “Measuring FID, TCD, uECD, and flows”. Agilent 7890 Series Troubleshooting...
Page 66: Contamination (High Baseline)
To Replace the uECD Fused Silica Indented Mixing Liner and Install the Makeup Gas Adapter. • If the detector baseline is > 500 Hz, regardless of detector age, bakeout the detector. Let it run for 1–2 days. Agilent 7890 Series Troubleshooting...
Page 67: Low Peak Area Or Height (Low Sensitivity)
• If the drop in peak area or height happened gradually due to baseline rise, rather than a sudden change, check for detector contamination. Bakeout the detector (FID, TCD, uECD). Agilent 7890 Series Troubleshooting...
Page 68: To Resolve Low Sensitivity With An Fid
For sensitivity loss associated with noise, wander, or drift, also “Noisy Detector, Including Wander, Drift, and Baseline Spikes”. Check detector flow settings. See Recommended starting conditions for new FID methods. The general rule is 1:1 flow ratio of hydrogen to (column + makeup gas). Agilent 7890 Series Troubleshooting...
Page 69 See the maintenance manual “Checking for Leaks”. Perform complete FID maintenance. Disassemble the FID and clean or replace all parts. Refer to the following: • To Perform Maintenance on the FID Collector Assembly Agilent 7890 Series Troubleshooting...
Page 70: Fid Flame Goes Out During A Run And Attempts To Reignite
• Check to see if an aromatic peak or water extinguished the flame. • Check for a partially plugged jet. Measure actual hydrogen, air, and makeup flows at the detector. (See “To Measure a Detector Flow”.) Replace the as needed. Agilent 7890 Series Troubleshooting...
Page 71 Install a Capillary Column in the FID. Make sure the column is installed all the way to the tip and withdrawn 1–2 mm (column id > 100 μm). • Check for leaks at the detector column fitting. (See “Checking Leaks”.) Agilent 7890 Series Troubleshooting...
Page 72: Fid Baseline Output Above 20 Pa
• Verify that the detector was reassembled properly after recent maintenance. • Inspect the detector for contamination. Bake out detector. • Check that the FID leakage current is < 2.0 pA. (See “To Measure FID Leakage Current”.) Agilent 7890 Series Troubleshooting...
Page 73: Fid Baseline Output At Maximum (~8 Million)
To avoid this problem, operate the detector at >300 °C. Reassemble and install the collector and operate the detector using higher air and hydrogen flows (air must be 450 mL/min, hydrogen at 35 mL/min). Agilent 7890 Series Troubleshooting...
Page 74: Fpd Flame Goes Out During A Run And Attempts To Reignite
You can verify that the flame is lit by holding a cold, shiny surface (such as a mirror or a wrench) over the exit tube. Condensation on the surface indicates that the flame is lit. Reset the Lit offset to 2.0. Agilent 7890 Series Troubleshooting...
Page 75: Fpd Quenching/Repeatability
Run the analysis first on a FID in order to see all the peaks (the FPD ignores hydrocarbons). Run the analysis on the FPD. Modify the method so that the peak of interest is separate from the rest of the peaks. Agilent 7890 Series Troubleshooting...
Page 76: Fpd Output Too High Or Too Low
• If the output < 30, the flame may be in the wrong position. Check detector flows, column flow, and column position. See the following: • To Measure a Column Flow • To Measure a Detector Flow Agilent 7890 Series Troubleshooting...
Page 77: Fpd Low Peak Areas
• Consider the filter type (sulfur or phosphorus). • Check the system for leaks. (See “Checking for Leaks”.) • Verify that the method settings are appropriate. • Check the flow rates. • Check the makeup gas type. Agilent 7890 Series Troubleshooting...
Page 78: 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. Agilent 7890 Series Troubleshooting...
Page 79: Fpd Baseline Output High, > 20 Pa
• Check for light leaks at the photomultiplier tube (PMT); tighten the PMT if it is loose. • Perform complete inlet maintenance: Replace all consumable parts and bake out the inlet. • Perform column maintenance: Bake out contaminants as needed. Agilent 7890 Series Troubleshooting...
Page 80: Npd Solvent Quenching
• Set the total column flow and makeup gas to less than 10 mL/min. • Increase the air flow by 10 mL/min. • Increase the detector temperature to 325 °C. • Implement an Agilent Dean’s switch solvent vent solution. Agilent 7890 Series Troubleshooting...
Page 81: Npd Response Low
To Check for a Plugged Jet. • If the upper ceramic insulator is contaminated, a high offset (2 to 15 pA or more) will occur when the bead is off. This directly affects sensitivity. Replace the ceramic insulator. Agilent 7890 Series Troubleshooting...
Page 82 If 4 V are being supplied to the bead but it is not igniting, the bead is probably burned out. Replace the bead. • Replace the insulators/collector. • Check for liquid phase contamination (polar phases). Agilent 7890 Series Troubleshooting...
Page 83: Npd Baseline Output > 8 Million
Chromatographic Symptoms NPD Baseline Output > 8 million • The collector is shorted to the detector housing. Disassemble the collector and insulators and reinstall. Agilent 7890 Series Troubleshooting...
Page 84: Npd Adjust Offset Process Not Functioning Properly
• If the process still fails, there could be a large leak in the system. This causes measured flow rates to be different from actual flow rates. Thoroughly leak check the whole system, especially the detector column fitting. (See Checking for Leaks.) • Set the equilibration time to 0.0. Agilent 7890 Series Troubleshooting...
Page 85: Npd Low Selectivity
(High hydrocarbon response relative to nitrogen or phosphorus.) • 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. Agilent 7890 Series Troubleshooting...
Page 86: Negative Peaks Seen With Tcd
• Check for a leak in the system, especially at the detector column fitting. (See “Checking for Leaks”.) • Consider thermal conductivity of analytes relative to carrier. • Check the flow settings, then measure the actual detector flows. (See “To Measure a Detector Flow”.) Agilent 7890 Series Troubleshooting...
Page 87: Tcd Baseline Has Dampened Sinusoidal Noise Trailing Peaks (Ringing Baseline)
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. Agilent 7890 Series Troubleshooting...
Page 88: Tcd Peaks Have Negative Dip On Tail
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. Agilent 7890 Series Troubleshooting...
Page 89: Gc Not Ready Symptoms
Agilent 7890 Series Gas Chromatograph Troubleshooting GC Not Ready Symptoms GC Never Becomes Ready 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...
Page 90: Gc Never Becomes Ready
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 7890 GC Advanced User Guide. Agilent 7890 Series Troubleshooting...
Page 91: Flow Never Becomes Ready
Advanced User Guide. • Check the configured gas type. The configured gas type must match the actual gas plumbed to the GC. • Check for leaks in the gas delivery plumbing and the GC. (See “Checking for Leaks”.) Agilent 7890 Series Troubleshooting...
Page 92: Oven Temperature Never Cools Down/Cools Very Slowly
If the flaps are not operating smoothly, contact Agilent for service. If using cryo cooling: • Check for sufficient cryo coolant. • Check if operating limits have been exceeded. Agilent 7890 Series Troubleshooting...
Page 93: Oven Never Heats Up
Verify that the oven flaps in the back of the GC are closed. The figure below illustrates the location of the two oven flaps. If the flap is stuck open or if the flaps are closed and the oven still does not heat, contact Agilent. Agilent 7890 Series Troubleshooting...
Page 94: Temperature Never Becomes Ready
Check if operating limits have been exceeded. If, for example, you are operating the GC in a hot room at a high oven temperature and a very low inlet temperature, an inlet may not reach its desired temperature. Agilent 7890 Series Troubleshooting...
Page 95: Cannot Set A Flow Or Pressure
• Check that the flow is turned on. • Check the inlet mode. When using inlet flow control, you can set only flow control modes for columns. When using inlet pressure control, you can set the column for both flow and pressure modes. Agilent 7890 Series Troubleshooting...
Page 96: A Gas Does Not Reach Setpoint Pressure Or Flow
• Check for an incorrectly installed column. • Check for a defective inlet or detector pressure sensor. If you are using a split/splitless inlet, MMI inlet, PTV inlet, or volatiles interface: • Check the split ratio. Increase the amount of split flow. Agilent 7890 Series Troubleshooting...
Page 97: A Gas Exceeds Pressure Setpoint Or Flow
If using an FID or NPD: • Check for a plugged jet. See “To Check for a Plugged FID Jet” “To Check for a Plugged NPD Jet”. Valves: • Check for a misaligned rotor. Align the rotor. Agilent 7890 Series Troubleshooting...
Page 98: The Inlet Pressure Or Flow Fluctuates
Correct laboratory temperature problem or move the instrument to a more suitable location. • Check for a restriction in headspace, purge and trap, and any other external sampling devices. • Verify Auto Flow Zero feature is On. See AutoFlowZero. Agilent 7890 Series Troubleshooting...
Page 99: Cannot Maintain A Pressure As Low As The Setpoint On A Split Inlet
To Check or Monitor Split Vent Line Backpressure • To Run the Inlet Trap Check • To Check a Split Vent Line for Contamination • For the split/splitless inlet, replace gold seal..See To Replace the Gold Seal on the Split/Splitless Inlet. Agilent 7890 Series Troubleshooting...
Page 100: The Measured Column Flow Does Not Equal The Displayed Flow
MSD. • Make sure that the auto flow zero is turned on. As applicable, zero the flow and pressure sensor for the flow module. If this does not solve the problem, replace the flow module. Agilent 7890 Series Troubleshooting...
Page 101: Fid Does Not Ignite
• Check the column flow rate. (See To Measure a Column Flow.) Hydrogen flow should be greater than the sum of the column flow and makeup flow. • If the analysis permits, substitute nitrogen for helium as makeup. Agilent 7890 Series Troubleshooting...
Page 102: Fid Ignitor Does Not Glow During Injection Sequence
• The ignitor is not making a good connection to the ground: • The ignitor must be tightly screwed into the FID castle assembly. • The three T-20 Torx screws that hold the collector assembly in place must be tight. Agilent 7890 Series Troubleshooting...
Page 103 GC Not Ready Symptoms • The brass knurled nut that holds the FID castle assembly in place must be tight. Perform FID maintenance if these parts are corroded or oxidized. T-20 Torx screws (3) Ignitor Knurled nut Agilent 7890 Series Troubleshooting...
Page 104: Fid Or Npd Measured Hydrogen And Makeup Gas Flows Much Less Than Setpoint
The actual flow rate will drop but the GC remains functional. See: “To Check for a Plugged FID Jet” “To Check for a Plugged NPD Jet” • Check for a column fitting leak at the detector base. • Replace the jet. Agilent 7890 Series Troubleshooting...
Page 105: Npd Adjust Offset Process Fails
• If the process still fails, there could be a large leak in the system. This causes measured flow rates to be different from actual flow rates. Thoroughly leak check the whole system, especially the detector column fitting. (See Checking for Leaks.) • Set the equilibration time to 0.0. Agilent 7890 Series Troubleshooting...
Page 106: Fpd Does Not Ignite
• Measure the actual detector flows. (See To Measure a Detector Flow.) • The column may be installed too high into the detector. • Check that the FPD ignitor operates. (See To Verify That the FPD Flame Is Lit.) Agilent 7890 Series Troubleshooting...
Page 107 FPD ). Try changing to the phosphorus mode flows, lighting the flame, and gradually alter the flows to the sulfur values. • Check cable connections to coupling, coupling connection to glow plug, tight glow plug. Agilent 7890 Series Troubleshooting...
Page 108: Valve Not Ready
The valve will most likely shutdown with Illegal Position or Not Switching shutdown errors. • If the valve is plugged or the sample is viscous, the switching time may be too short for the valve to switch. Increase the switching time. Agilent 7890 Series Troubleshooting...
Page 109: Blinking Not Ready Light: Detector Hardware Fault/Tcd Filament Voltage
Contact Agilent for service. To continue to use the GC without the TCD: Turn off all TCD parameters. Save the method. Reconfigure the GC to use another detector. Move the column and set other parameters as needed. Agilent 7890 Series Troubleshooting...
Page 110 GC Not Ready Symptoms Agilent 7890 Series Troubleshooting...
Page 111 Agilent 7890 Series Gas Chromatograph Troubleshooting Shutdown Symptoms Column Shutdowns Hydrogen Shutdowns Detector Air Shutdowns 7890B MS Shutdown Thermal Shutdowns Agilent Technologies...
Page 112: Shutdown Symptoms
Replace the inlet septum. • Replace the inlet O-ring. • Check the supply pressure. Press the key for the device that initiated the shutdown. Scroll to the pneumatic parameter that is flashing Off, then press [On] or [Off]. Agilent 7890 Series Troubleshooting...
Page 113 For example, if the front inlet ran out of carrier gas, press [Front Inlet], scroll to the pressure or flow parameter, then press [On]. • After a column shutdown, you can turn on a detector gas flow even if the keyboard is locked by a data system. Agilent 7890 Series Troubleshooting...
Page 114: Hydrogen Shutdowns
FID, NPD, and any other detectors that use hydrogen always be connected to a column or have a cap or plug installed and that hydrogen streams be configured so that the GC is aware of them. Agilent 7890 Series Troubleshooting...
Page 115: Hydrogen Sensor
If equipped with the optional hydrogen sensor, the GC will perform a hydrogen safety shutdown if the sensor measures an uncombusted hydrogen concentration of about 1 % in the oven (about 25 % of the lower explosive limit for hydrogen). Agilent 7890 Series Troubleshooting...
Page 116: Detector Air Shutdowns
690–827 kPa (100–120 psi). See the Agilent GC, GC/MS, and ALS Site Preparation Guide. Press the key for the detector that initiated the shutdown. Scroll to each pneumatic parameter that is flashing Off, then press [On] or [Off]. Agilent 7890 Series Troubleshooting...
Page 117: 7890B Ms Shutdown
Check the GC and MS LAN connections. Is the LAN switch or hub operating? 5977B: Press [Config][MS/Aux Det]. The Lvds communication setting should read On. Check the GC and MS LAN connections. Is the LAN switch or hub operating? Agilent 7890 Series Troubleshooting...
Page 118: Clearing An Ms Shutdown
After resolving an MS Shutdown After resolving the GC or MS problem, always restore GC to MS communications. 5977A, 7000C, 7010: Press [MS/Aux Det]. Scroll to MS Communication. Press On/Yes. 5977B: Press [Config][MS/Aux Det]. Scroll to Lvds communication. Press On/Yes. Agilent 7890 Series Troubleshooting...
Page 119: Thermal Shutdowns
• A shorted temperature sensor. • A shorted heater. To recover from this state: Fix the cause of the shutdown: • Check for missing insulation. Most thermal shutdowns can be cleared by shutting off the thermal zone. Agilent 7890 Series Troubleshooting...
Page 120 Shutdown Symptoms Agilent 7890 Series Troubleshooting...
Page 121 Agilent 7890 Series Gas Chromatograph Troubleshooting GC Power On and Communication Symptoms GC Does Not Turn On PC Cannot Communicate with GC GC Cannot Communicate with a Configured MS or HS GC Does Not Recover After Firmware Update GC Turns On, Then Stops During Startup (During Self-Test)
Page 122: Gc Power On And Communication Symptoms
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. Agilent 7890 Series Troubleshooting...
Page 123: Pc Cannot Communicate With Gc
• If using a direct PC to GC setup, make sure you are using a crossover cable. If using a setup with a hub or switch (that is, connecting to a building or site LAN), make sure you are NOT using a crossover cable. Agilent 7890 Series Troubleshooting...
Page 124: Gc Cannot Communicate With A Configured Ms Or Hs
PC ping command.) If using an Agilent data system, check the GC, HS, and MS IP addresses entered into the data system software. Again, these must exactly match the values entered into each instrument. Agilent 7890 Series Troubleshooting...
Page 125: Gc Does Not Recover After Firmware Update
If this display appears, you can now communicate to the GC. Reload the firmware. If the GC does not boot up and show a display similar to the one above, or if the update fails again, contact Agilent for service. Agilent 7890 Series Troubleshooting...
Page 126: Gc Turns On, Then Stops During Startup (During Self-Test)
Contact Agilent for service, and provide the display information to the Agilent support personnel. (See also “Information to Obtain Before Calling Agilent for Service”.) Older GC: LEDs visible through side panel. Agilent 7890 Series Troubleshooting...
Page 127: Checking For Leaks
Agilent 7890 Series Gas Chromatograph Troubleshooting Checking for Leaks Leak Check Tips To Check for External Leaks To Check for GC Leaks Leaks in Capillary Flow Fittings To Perform an Inlet Leak Check To Check for Leaks in a Split/Splitless Inlet...
Page 128: Leak Check Tips
Use the electronic leak detector to determine if a fitting is leaking. • Start by checking any newly made connections first. • Remember to check connections in the gas supply lines after changing traps or supply cylinders. Agilent 7890 Series Troubleshooting...
Page 129: To Check For External Leaks
• Gas supply bulkhead fittings • Gas cylinder fitting • Regulator fittings • Traps • Shut-off valves • T-fittings Perform a pressure drop test. Turn off the GC. Set the regulator pressure to 415 kPa (60 psi). Agilent 7890 Series Troubleshooting...
Page 130 Checking for Leaks Fully turn the regulator pressure adjustment knob counterclockwise to shut the valve. Wait 10 min. If there is a pressure loss greater than 7 kPa (1 psi), there is a leak in the external connections. Agilent 7890 Series Troubleshooting...
Page 131: To Check For Gc Leaks
Use an electronic leak detector to check column connections and tubing connections. See also: • To Check for Leaks in a Split/Splitless Inlet • To Check for Leaks in a Multimode Inlet • Leaks in Capillary Flow Fittings Agilent 7890 Series Troubleshooting...
Page 132: Leaks In Capillary Flow Fittings
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. Agilent 7890 Series Troubleshooting...
Page 133: To Perform An Inlet Leak Check
Tue Oct 20 16:07 2009 Test flow OK: Reset the test results? (yes) Figure 4 Example front inlet leak check display. Example assumes a test has been previously run. (Scroll the display to see all lines.) Agilent 7890 Series Troubleshooting...
Page 134 To Perform a SS Pressure Decay Leak Test • To Perform a MMI Pressure Decay Test • To Perform a PP Pressure Decay Leak Test • To Perform a PTV Pressure Decay Test • To Perform a VI Pressure Decay Test Agilent 7890 Series Troubleshooting...
Page 135: To Set Warning Limits For A Leak Check
Scroll to Reset the test results? and press [On/Yes]. To disable a warning limit for the inlet leak check Press [Service Mode], scroll to Front inlet leak check or Back inlet leak check, then press [Enter]. Scroll to the warning limit, then press [Off/No]. Agilent 7890 Series Troubleshooting...
Page 136: To Check For Leaks In A Split/Splitless Inlet
“To Perform an Inlet Leak Check”. The total flow provides an indication of the magnitude of the leak. Monitor the total flow while checking/tightening fittings: • Septum nut • Column • Split vent trap/O-rings • Liner/O-rings • Gold seal Agilent 7890 Series Troubleshooting...
Page 137: Low Sensitivity Or Poor Repeatability
If the inlet (prep run) leak check did not resolve the problem, the leak may be too small to detect using that test. Use an electronic leak detector to check the fittings/connections. If these checks do not resolve the problem, contact Agilent for service. Agilent 7890 Series Troubleshooting...
Page 138: To Perform A Ss Pressure Decay Leak Test
The pressure decay leak test described below requires removing the column and capping the inlet column fitting. This test can/cannot find the following types of leaks: Agilent 7890 Series Troubleshooting...
Page 139 Inspect the O-ring and replace it if it is hard and brittle or cracked. See To change the liner and O-ring on the split/splitless inlet. Set the inlet to Split Mode. Agilent 7890 Series Troubleshooting...
Page 140 Allow the inlet temperature to stabilize. Temperature changes can invalidate the test. Cap the septum purge fitting with the ECD/TCD detector plug. Back inlet split Back inlet purge vent vent Front inlet split vent Front inlet purge vent Agilent 7890 Series Troubleshooting...
Page 141 11.7 kPa or 1.17 kPa/min) is acceptable. If the 7697A passes all its leak tests (restriction, pressure decay, and cross port), and if the GC inlet pressure decay test passes without the 7697A installed, check the 7697A carrier flow path. See the Headspace Sampler documentation. Agilent 7890 Series Troubleshooting...
Page 142 After the inlet passes the test, restore the GC to operating condition. • Restore source pressures. • Remove any caps/plugs. • Reinstall the column. • Restore the correct column configuration. • Load the operating method. Agilent 7890 Series Troubleshooting...
Page 143: To Correct Leaks In The Split Splitless Inlet
• If you changed the gold seal, verify correct installation. See To replace the gold seal on the split/splitless inlet. • Make sure the inlet temperature remained constant during the test. If these items do not resolve the problem, contact Agilent for service. Agilent 7890 Series Troubleshooting...
Page 144: To Check For Leaks In A Multimode Inlet
Check”. The total flow provides an indication of the magnitude of the leak. Monitor the total flow while checking/tightening fittings: • Septum nut • Column • Split vent trap/O-rings • Liner/O-rings • Split vent line connection to the inlet body Agilent 7890 Series Troubleshooting...
Page 145: Low Sensitivity Or Poor Repeatability
Flow block fittings on the flow manifold If the problem continues, the leak may be small. Use an electronic leak detector to check the fittings/connections. If these checks do not resolve the problem, contact Agilent for service. Agilent 7890 Series Troubleshooting...
Page 146: To Perform A Mmi Pressure Decay Test
The pressure decay leak test described below requires removing the column and capping the inlet column fitting. This test can/cannot find the following types of leaks: Agilent 7890 Series Troubleshooting...
Page 147 Inspect the O-ring and replace it if it is hard and brittle or cracked. See To change the liner and O-ring on the Multimode inlet. Set the inlet to Split Mode. Configure the column as Inlet: Unspecified. Set the inlet temperature to 70 °C. Agilent 7890 Series Troubleshooting...
Page 148 Cap the septum purge fitting with the ECD/TCD detector plug. Back inlet split Back inlet purge vent vent Front inlet split vent Front inlet purge vent Front purge vent shown plugged Agilent 7890 Series Troubleshooting...
Page 149 After the inlet passes the test, restore the GC to operating condition. • Remove any caps/plugs. • Reinstall the column. • Restore the correct column configuration. • Load the operating method. Agilent 7890 Series Troubleshooting...
Page 150: To Correct Leaks In The Multimode Inlet
• Check the liner and liner O-ring. See To change the liner and O-ring on the Multimode inlet. • Make sure the inlet temperature remained constant during the test. If these items do not resolve the problem, contact Agilent for service. Agilent 7890 Series Troubleshooting...
Page 151: To Perform A Pp Pressure Decay Leak Test
The test can find leaks at the: The test cannot find leaks at the: septum column fitting septum nut gas supply bulkhead fittings to the flow module glass insert O-ring seal adapter and ferrule inlet body top insert weldment Agilent 7890 Series Troubleshooting...
Page 152 Set the inlet temperature to 100 °C. Enter a pressure setpoint of 25 psi (172 kPa). Make sure that the pressure supplied to the GC is at least 10 psi (70 kPa) higher than the inlet pressure. Agilent 7890 Series Troubleshooting...
Page 153 From the keypad, press [Service Mode]. Select Diagnostics > Front or Back Inlet > Pneumatics Control > Septum Purge control. Scroll to the Constant duty cycle and enter 50. Wait 10 seconds. Press [Front or Back Inlet]. Scroll to Pressure and press Off/No. Agilent 7890 Series Troubleshooting...
Page 154 Inlet”. Retest. After the inlet passes the test, restore the GC to operating condition. • Remove any caps/plugs. • Restore source pressures. • Reinstall the column. • Restore the correct column configuration. • Load the operating method. Agilent 7890 Series Troubleshooting...
Page 155: To Correct Leaks In The Packed Column Inlet
PP inlet. • Replace the ferrule seal on the adapter. • Make sure the inlet temperature remained constant during the test. If these items do not resolve the problem, contact Agilent for service. Agilent 7890 Series Troubleshooting...
Page 156: To Perform A Coc Pressure Decay Leak Test
See “To Check for External Leaks”. The pressure decay leak test described below requires removing the column and capping the inlet column fitting. This test can/cannot find the following types of leaks: Agilent 7890 Series Troubleshooting...
Page 157 Set the Septum purge flow to 3.0 mL/min. Allow the inlet temperature to stabilize. Temperature changes can invalidate the test. Agilent 7890 Series Troubleshooting...
Page 158 (Such leaks in through the EPC module typically do not impact runs.) If the setup does not include shutoff valves at the GC, or if Agilent 7890 Series Troubleshooting...
Page 159 Inlet”. Retest. After the inlet passes the test, restore the GC to operating condition. • Restore source pressures. • Remove any caps/plugs. • Reinstall the column. • Restore the correct column configuration. • Load the operating method. Agilent 7890 Series Troubleshooting...
Page 160: To Correct Leaks In The Cool On-Column Inlet
COC inlet. • Check the septum. Replace if old or damaged. • Make sure the inlet temperature remained constant during the test. If these items do not resolve the problem, contact Agilent for service. Agilent 7890 Series Troubleshooting...
Page 161: To Perform A Ptv Pressure Decay Test
The pressure decay leak test described below requires removing the column and capping the inlet column fitting. This test can/cannot find the following types of leaks: Agilent 7890 Series Troubleshooting...
Page 162 See To change the septum on the PTV inlet To change the liner on the PTV inlet. Set the inlet to Split Mode. Configure the column as 0 length. Set the inlet temperature to 100 °C. Agilent 7890 Series Troubleshooting...
Page 163 Cap the septum purge fitting with the ECD/TCD detector plug. Back inlet split Back inlet purge vent vent Front inlet split vent Front inlet purge vent Front purge vent shown plugged Agilent 7890 Series Troubleshooting...
Page 164 After the inlet passes the test, restore the GC to operating condition. • Restore source pressures. • Remove any caps/plugs. • Reinstall the column. • Restore the correct column configuration. • Load the operating method. Agilent 7890 Series Troubleshooting...
Page 165: To Correct Leaks In The Ptv Inlet
Replace the split vent trap filter and O-rings. See To replace the filter in the PTV inlet split vent line. • Make sure the inlet temperature remained constant during the test. If these items not resolve the problem, contact Agilent for service. Agilent 7890 Series Troubleshooting...
Page 166: To Perform A Vi Pressure Decay Test
The pressure decay leak test described below requires removing the column and capping the inlet column fitting. This test can/cannot find the following types of leaks: Agilent 7890 Series Troubleshooting...
Page 167 If pressure cannot be achieved, there is either a large leak or the supply pressure is too low. Set the Septum purge flow to 3.0 mL/min. Allow the inlet temperature to stabilize. Temperature changes can invalidate the test. Agilent 7890 Series Troubleshooting...
Page 168 (Such leaks in through the EPC module typically do not impact runs.) If the setup does not include shutoff valves at the GC, or if Agilent 7890 Series Troubleshooting...
Page 169 After the VI passes the test, restore the GC to operating condition. • Restore source pressures. • Remove any caps/plugs. • If needed, reconnect the sampling device. • Reinstall the column. • Restore the correct column configuration. • Load the operating method. Agilent 7890 Series Troubleshooting...
Page 170: To Prepare The Vi For A Closed System Leak Check
Connect the carrier line to the interface where you removed the transfer line and tighten the nut finger tight. Tighten an additional 1/4 to 1/2 turn with the 1/4-inch wrench. Return to “To Perform a VI Pressure Decay Test” and repeat steps to 16. Agilent 7890 Series Troubleshooting...
Page 171: To Correct Leaks In The Volatiles Interface
• The split vent and pressure sensing connections at the interface. • The sampler connection to the interface. • The sampler. If these items do not resolve the problem, contact Agilent for service. Agilent 7890 Series Troubleshooting...
Page 172 Checking for Leaks Agilent 7890 Series Troubleshooting...
Page 173 Agilent 7890 Series Gas Chromatograph Troubleshooting Troubleshooting Tasks To Measure a Column Flow To Measure a Split Vent or Septum Purge Flow To Measure a Detector Flow To Perform the GC Self-Test To Check or Monitor Split Vent Line Backpressure...
Page 174: Troubleshooting Tasks
Insert the adapter into the detector exhaust vent as far as possible. You will feel resistance as the adapter O-ring is forced into the detector exhaust vent. Twist and push the adapter during insertion to ensure a good seal. Agilent 7890 Series Troubleshooting...
Page 175 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. Agilent 7890 Series Troubleshooting...
Page 176: Measuring Npd Column Flow
Be careful! The detector may be hot enough to cause burns. If the WA RNING detector is hot, wear heat-resistant gloves to protect your hands. Remove the bead and store it carefully until reinstallation. Insert the NPD flowmeter adapter tool into the NPD collector. Agilent 7890 Series Troubleshooting...
Page 177 Troubleshooting Tasks Attach the flow-measuring insert to the NPD flowmeter adapter tool. Place the flowmeter tubing over the flow-measuring insert to begin measuring flows. Agilent 7890 Series Troubleshooting...
Page 178: To Measure A Split Vent Or Septum Purge Flow
Front inlet split vent Front inlet purge vent To measure split vent or septum purge flows, attach the flowmeter to the appropriate tube. Remove the GC pneumatics cover to access the back inlet exhausts. Agilent 7890 Series Troubleshooting...
Page 179 • The septum purge is a 1/8-in tube. Use the red rubber adapter shown to measure flows. Agilent 7890 Series Troubleshooting...
Page 180: To Measure A Detector Flow
To avoid damaging the column, cool the oven before turning off the C A U T I O N column flow. Set the oven temperature to ambient (35 °C). Turn off the column flow and pressure. Shut off all detector gases. Agilent 7890 Series Troubleshooting...
Page 181 Insert the adapter into the detector exhaust vent as far as possible. You will feel resistance as the adapter O-ring is forced into the detector exhaust vent. Twist and push the adapter during insertion to ensure a good seal. Agilent 7890 Series Troubleshooting...
Page 182 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. Agilent 7890 Series Troubleshooting...
Page 183: Measuring Npd Flows
Be careful! The detector may be hot enough to cause burns. If the WA RNING detector is hot, wear heat-resistant gloves to protect your hands. Remove the bead and store it carefully until reinstallation. Insert the NPD flowmeter adapter tool into the NPD collector. Agilent 7890 Series Troubleshooting...
Page 184 Troubleshooting Tasks Attach the flow-measuring insert to the NPD flowmeter adapter tool. Place the flowmeter tubing over the flow-measuring insert to begin measuring flows. Agilent 7890 Series Troubleshooting...
Page 185: To Perform The Gc Self-Test
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. Agilent 7890 Series Troubleshooting...
Page 186: To Check Or Monitor Split Vent Line Backpressure
To use the inlet trap check to monitor the split vent trap: If the existing split vent trap has been used for many sample injections, replace it. Make sure that the GC is clean: • Replace inlet hardware if needed. Agilent 7890 Series Troubleshooting...
Page 187 To clear a Not Ready condition or to turn off the Service Due indicator: Press [Service Mode], scroll to Front inlet trap check or to Back inlet trap check, then press [Enter]. Scroll to Reset the test results? and press [On/Yes]. Agilent 7890 Series Troubleshooting...
Page 188: To Disable A Warning Limit For The Inlet Trap Check
Troubleshooting Tasks To disable a warning limit for the inlet trap check Press [Service Mode], scroll to Front inlet trap check or Back inlet trap check, then press [Enter]. Scroll to the warning, then press [Off/No]. Agilent 7890 Series Troubleshooting...
Page 189: To Run The Inlet Trap Check
“To Check or Monitor Split Vent Line Backpressure”. Typical pressures for a clean split flow path are: • 1–2 psi (7–14 kPa) at 400 mL/min for a split liner • 3–10 psi (21–69 kPa) at 400 mL/min for a splitless liner Agilent 7890 Series Troubleshooting...
Page 190 The most recent test results display at the bottom of the display. Scroll N O T E down to see them. To clear a Not Ready condition or Service Due indicator, scroll to Reset the test results? and press [On/Yes]. Agilent 7890 Series Troubleshooting...
Page 191: To Perform A Ss Split Vent Restriction Test
5182-9652. • Check for contamination in the split vent line. See “To Check a Split Vent Line for Contamination”. If the problem remains, contact Agilent for service. Agilent 7890 Series Troubleshooting...
Page 192: To Check A Split Vent Line For Contamination
Clean the split tube with a brush and suitable solvent. Reassemble the split/splitless inlet and run the split vent restriction test to test for restrictions in the split vent flow path. If the inlet still fails, suspect flow module contamination or defects. Agilent 7890 Series Troubleshooting...
Page 193 Troubleshooting Tasks Check for leaks. Run the pressure decay test. See “To Perform a SS Pressure Decay Leak Test” or “To Perform a MMI Pressure Decay Leak Test”. Agilent 7890 Series Troubleshooting...
Page 194: To Adjust The Fid Lit Offset
Scroll to Lit offset. With the Lit offset line highlighted, enter the new parameter for the detector and press [Enter]. Lit offset should be < 2.0 pA or lower than the normal FID output when lit. Agilent 7890 Series Troubleshooting...
Page 195: To Verify That The Fid Flame Is Lit
• Verify that the detector temperature is above 150 °C. Agilent  recommends operating the FID 300 °C. • Verify correct detector flows. • Inspect the jet for contamination. • Verify that the jet is installed correctly. • Check the column connections for leaks. Agilent 7890 Series Troubleshooting...
Page 196: To Verify Fid Ignitor Function During Ignition Sequence
If using hydrogen, the FID flame will not be visible. Remove the detector top cover. Turn the FID flame On. Observe the ignitor plug though the FID chimney. The small hole should glow during ignition sequence. Agilent 7890 Series Troubleshooting...
Page 197: To Measure Fid Leakage Current
If the output is unstable or > 1.0 pA, turn off the GC and check for proper assembly of the upper FID parts and for contamination. If the contamination is confined to the detector, bakeout the FID. Turn on the flame. Agilent 7890 Series Troubleshooting...
Page 198: To Measure Fid Baseline Output
< 20 pA (this may take some time). If the output is not stable or > 20 pA, the system or gas may be contaminated. If this contamination is isolated to the detector, bakeout the FID. Agilent 7890 Series Troubleshooting...
Page 199: To Isolate The Cause Of Fid Noise
If the leakage current test is OK, suspect a contaminated jet or contaminated H2 or Air detector gas supplies (gases, tubing, traps), especially if the background of the detector when lit is >20 pA. Agilent 7890 Series Troubleshooting...
Page 200: To Measure Npd Leakage Current
• Inspect the for contamination. • Check the column or column adapter fitting for leaks. • Ensure that the metal sealing ring is not crushed or misaligned. See To Maintain the NPD Collector, Ceramic Insulators, and Jet Agilent 7890 Series Troubleshooting...
Page 201: To Check For A Plugged Fid Jet
EPC system, resulting in a false flow indication on the makeup channel. Alternately, remove the jet from the housing and hold it up to a light source. Check the holes in the jet for contamination. If plugged, replace the jet. Agilent 7890 Series Troubleshooting...
Page 202: To Check For A Plugged Npd Jet
A plugged jet will cause inaccurate flow readings. To check for a plugged NPD jet, measure the actual hydrogen and makeup flows. (See Measuring NPD flows.) If the flows are lower than the displayed values, replace the jet. Agilent 7890 Series Troubleshooting...
Page 203: To Verify That The Npd Bead Is Ignited
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 pA. Agilent 7890 Series Troubleshooting...
Page 204: 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. Agilent 7890 Series Troubleshooting...
Page 205: To Adjust The Fpd Lit Offset
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]. Agilent 7890 Series Troubleshooting...
Page 206: When To Change Gas Purifiers
Agilent’s OT3 oxygen trap, for example, has a capacity of 600 mg O2. Therefore, you need to replace the OT3 trap every 10 cylinders. This is just a rough estimate, and it is prudent to change traps too early rather than too late. Agilent 7890 Series Troubleshooting...
Page 207: To Ignore A Device's Readiness State
Be sure to return a broken device to Ignore Ready = False after it is repaired. Otherwise, its state (temperature, flow, pressure, and so forth) will continue to be ignored, even if using this device in the analysis. To consider a device’s readiness, set Ignore Ready to False. Agilent 7890 Series Troubleshooting...
Page 208: To Use The Stopwatch
Agilent Technologies To Use the Stopwatch In the stopwatch mode, both the time (to 0.1 second) and reciprocal time (to 0.01 min—1) are displayed. Use the stopwatch when measuring flows with a bubble flowmeter. Press [Time] and scroll to the time = line.

This manual is also suitable for:

7890a

Agilent Technologies 7890 Series Troubleshooting Manual

1 Concepts and General Tasks

2 ALS and Detector Symptoms

3 Chromatographic Symptoms

4 GC Not Ready Symptoms

5 Shutdown Symptoms

6 GC Power on and Communication Symptoms

7 Checking for Leaks

8 Troubleshooting Tasks

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Summary of Contents for Agilent Technologies 7890 Series