User`s guide

Accessories
196
upon and set.
This function is available by selecting the Preferences entry on the
Tools menu and then selecting the Config tab and the Internal
Standards button. A dialog box will appear with the Loop Load
entry box.
After connecting the IS canister to the TD unit, you will manually
adjust the loop fill flow of the internal standard with the Loop Load
needle valve, while monitoring the flow with a suitable flowmeter at
the Loop Load vent (a flow of 20 mL is recommended).
This function is available by selecting the Maintenance entry on the
Tools tab and then selecting the option IS Loop Load.
When finished, press the Stop button to close the IS solenoid valve
ISV1 at the IS vent, to shut off the flow and conserve the expensive
standard gas.
You will need to enter a loop equilibration time by selecting the
Preferences entry on the Tools tab and then selecting the Internal
Standard button.
This calls up a dialog box that allows you to enter the Loop Equil
for the internal standard.
Selecting this check box enables solenoid valve ISV1 in the Internal
Standard accessory. While the valve is enabled, flow can be
monitored through the bleed vent barb at the same location.
Once the flow rate has been set, the Loop Equilibration time or the
time required for the loop pressure to reach ambient pressure must
be set. Prepare to measure the loop equilibration time by connecting
the vent to a bubbler. This device could be made from any vessel
capable of holding water into which a tube connected to the bleed
vent is inserted. While the gas is flowing through the loop, bubbles
will be seen exiting the tube into the water.
Disable solenoid valve ISV1 by deselecting the Load IS Loop check
box. The gas inside the loop is still under pressure and will continue
to exit the needle valve until it reaches ambient pressure. This will be
evident by the lack of bubbles. Time the interval between disabling
ISV1 and the loop pressure reaching ambient pressure. Enter this