User`s guide

Installation and Setup
80
7. Allow a few minutes for the flow to stabilize before
disconnecting the flow meter.
8. To set the desorb flow, connect a flow meter to the
desorb vent. Adjust the Desorb needle valve to obtain
the required flow. Typical desorb flow rates are in the
order of 20 to 100 mL/min.
If either helium or hydrogen is used for the carrier gas,
the desorb flow rate should not be higher than 100 mL/
min. If higher flow rates are used, the trap may not be
able to maintain its low temperature setpoint. Higher
flows also tend to cause a noticeable pressure drop
across the tube and trap.
9. Allow a few minutes for the flow to stabilize before
disconnecting the flow meter.
10. Connect the flow meter to the split vent again to check
the flow. Adjust the flow as necessary.
11. Connect the flow meter to the desorb vent again to
check the flow. Adjust the flow as necessary.
12. Repeat this process until you have obtained the required
flow rates
13. Press the Stop button to close the solenoid valves, return
the heated valve to its original position, and in the case
of the ATD, return the sample tube to the carousel.
NOTE: Recheck the flow rates when you are actually running a
sample, as the flows can be different when heat is applied.
Setting the Outlet Split Flow
A pressure regulator and fixed restrictor provide control over the
split flow. The pressure regulator used in the TurboMatrix design
allows you to precisely set the lower flow rates sometimes required
for outlet splitting.
A sample tube is not required to setup the outlet split flow gas
circuit. See Setting Sample Split Ratios on page 228 for details of
determining the value of the outlet split flow.
1. Open the Tool s menu and select Adjust Flows.