User guide

Checking for Leaks 6
Advanced User Guide 149
13
From the keypad, press [Service Mode]. Select Diagnostics >
Front or Back Inlet > Pneumatics Control > Septum Purge control.
14 Scroll to the Constant duty cycle and enter 50. Wait 10 seconds.
15 Press [Front or Back Inlet]. Scroll to Pressure and press Off/No.
16 Quickly turn off the carrier gas supply at its source.
17 Monitor the pressure for 10–15 minutes. Use the timer by
pressing [Time] and [Enter].
The pressure should drop approximately 1 psi (6.9 kPa)
during the first 1 to 2 minutes. After an initial pressure drop
of about 1 psi, the pressure should not drop more than
0.03 psi/min (0.21 kPa/min).
If the pressure drop is 0.03 psi/min or less, you can consider
the interface- gas sampler system leak- free.
If the pressure drops faster than the acceptable rate, you
must check the interface and sampler systems separately to
determine the source of the leak. See “To Prepare the VI for a
Closed System Leak Check” to create a closed flow system,
then return to this section and complete steps 10 to 15.
If you find a leak in the interface, refer to “To Correct Leaks
in the Volatiles Interface”.
If the interface is leak- free, pressure check the sampling
device. See the operating manual for your sampler for
instructions.
18 After the VI passes the test, restore the GC to operating
condition.
• Remove any caps/plugs.
• If needed, reconnect the sampling device.
• Reinstall the column.
• Restore the correct column configuration.
• Load the operating method.
Front purge vent shown plugged