Troubleshooting a Leak or Poor Chromatography on the Agilent 7697A Headspace Sampler

Answer

This Information Applies To: Agilent 7697A headspace sampler.

Issue:

The headspace sampler may present a flow shutdown or poor chromatography with decreased area counts or shifted retention times, caused by leaks or restrictions in the sampler. The hardware has a built-in restriction and pressure decay test that can be utilized to help with troubleshooting. 

Things to know about the test:

• Runs two tests successively, the restriction and pressure decay test and the crossport leak test.
• If one test reports a failure then the test reports the failure and stops before attempting any subsequent part.
• The test will check for restrictions and leaks in the vial pressurization and sampling flow path, not the carrier flow path.
• The test looks at the temperature and accounts for the actual temperature setpoint.
• The test should not be run above 210 °C.
• The blue leak test vial must be used.
• The tray must be unparked to run the test.
• “Pass” or “Fail” of the leak test is logged in the Maintenance Log.

Tools Required:

• 3/16- inch wrench
• 7/16- inch wrench
• 1/4- inch wrench
• 5/16- inch wrench
• Inlet Liner, O-ring, and septum as needed, if there are doubts about the condition of these consumables, replace them.
• Leak test kit (G4556- 67010), see Table 1

Table 1. Leak Test Kit Contents  

Item	Part Number
Six Port Valve Cap	G6600-80039
No Hole Ferrule	5181-7458
Blue Leak Test Vial	G1290-20600
1/8-inch Nylon Swagelok plug	0100-2414

Steps to Follow:

1. Set the active method vial size to 20 mL.
   1. Press [Vial], scroll to Vial size,
   2. Press [Mode/Type] to select the vial size from a list, then press [Enter].
2. Install a new septum into the blue leak test vial. 
3. Place the blue leak test vial into priority position 1 (111 vial model) or into tray position 1 (12 vial model).
4. Set the carrier pressure to a low flow
   1. If using HS Control or GC Control: a Cool the GC inlet and column oven.
   2. When cool, press [Carrier].
   3. Set the carrier pressure setpoint to 14 kPa (2 psi).
   4. If in a flow mode, reduce the flow setpoint until the carrier pressure is below 14 kPa (2 psi).)
   5. If using GC + HS Control: Press [Carrier], then reduce the flow setpoint until the carrier pressure is below 14 kPa (2 psi). 
   6. Leave the GC carrier pressure or flow unchanged.
5.  Start the test. Press [Service Mode], select Restriction & Pressure Decay, then press [Enter].

If the test Fails:

• The reading for the stage that failed (for example, leak rate or flow rate)
• Command lines that show the current status of the related valves (for example, a switching valve or the six-port valve). SV1, SV2, PV1, or PV2: To toggle these valves, scroll to this line and press [On/Yes] to turn on (energize) the valve, or [Off/No] to turn it off. Six-port valve: Scroll to this line and press [On/Yes] to switch the valve to the load position, or [Off/No] to switch it to the inject position.
• A selection to exit the test. Exit test? Select this line then press [On/Yes] to abort the test.

Failure at Restriction Test 1/3: Sample Probe (without sample loop in line)

• Confirm the gas type and verify it agrees with what is configured
• The restriction in sample probe, Remove the sample probe and confirm that there is no restriction, replace if necessary
• If the test fails after completing the following steps, then contact Agilent for onsite service

Failure at Restriction Test 2/3: Sample Probe (with sample loop in line)

• Confirm the sample loop configuration and that the installed sample loop matches
• Replace the sample loop (p/n G4556-80106)
• If the test fails after completing the following steps, then contact Agilent for onsite service

Tips: If the sampler has been running water samples that have been saturated with inorganic salts, these salts may have got in the probe and the valve. The valve can be removed and cleaned by removing the rotor and cleaning the 6 ports of the valve body with a cleaning wire (9301-0985). Contamination of the Flow Block Weldment is the least likely cause of the problem, unless higher boiling compounds are being analyzed. These tend to condense out in the condensation coil and block the Weldment.

Failure at Restriction Test 3/3: Vent Line

• An external vent line connected to the instrument vent. If using an external vent line, disconnect it from the instrument and rerun the test.
• A leak causing no restriction value (causing no pressure drop at this stage)
• If the test fails after completing the following steps, then contact Agilent for onsite service

Failure at Pressure Decay Test 1/3:

• If the test fails, then contact Agilent for onsite service

Failure at Pressure Decay Test 2/3:

• Blue leak test vial is being used
  • The septa is fully inserted in the leak test vial.
  • Verify this by making sure that the septa has bottomed out on the push hole
• If the test fails after completing the following steps, then contact Agilent for onsite service

Failure at Pressure Decay Test 3/3

• If the test fails, then contact Agilent for onsite service

If the test Passes:

Restore the instrument to operating condition. 

If the test passes all stages, the sampling system is leak free. If still experiencing leak-like symptoms or poor chromatography 

• Check the transfer line for leaks or restrictions
• Check for external leaks
• If not already done, check the GC, (The HS leak test cannot test for leaks in the GC)

Learn how to effectively troubleshoot your 7697A:  SI-7697A-2260r - How to Run the Agilent 7697A Headspace Sampler Restriction and Leak Tests e-learning available from Agilent education. Leak Testing the Headspace Sampler user manual on Agilent.com.