Maintaining the Instrument
Flow Testing the Vent Valve and Associated Flow Path
112
8. De-pressurize the system by opening the vent valve from MANUAL
OPERATION.
Flow Testing the Vent Valve and Associated Flow Path
Perform this test only after the system (all models) passes the carrier and
pressurize vial tests.
1. Prepare a new, empty 20 ml headspace vial. Make sure that it is capped
properly. See “Sample Preparation” on page 56.
2. Manually install the headspace vial under the probe in the headspace oven.
3. Set the Vial Pressure to 20 psi.
4. Place the vent exit tube from back of headspace in a beaker of water.
• If needed, extend the tube using 1/8-inch PTFE or similar tubing.
5. Using MANUAL OPERATION, load the vial onto the probe, set the vent
valve to “OFF” and set the pressurize valve to “ON.” (See “MANUAL
OPERATION” on page 48 for details.)
6. Wait at least 20 seconds for the vial to pressurize.
7. Using MANUAL OPERATION, turn Pressurize Valve “OFF” and set the
vent valve to “ON.”
8. Observe the vent tube in the water. The vent tube should produce bubbles
immediately when the vent is turned “ON” and the bubbling should stop
within 10–15 seconds. If the bubbling lasts much longer, the vent valve or
associated flowpath may be restricted. Contact Agilent service.
Note that if the vent flow path is restricted, you may be overpressurizing your
sample vials. When the problem is fixed, your sensitivity may appear to
decrease because you are now injecting the appropriate amount of sample for
your method.
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