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Constant and adequate sample flows are required for reproducible results
on the CATS system. Adequate sample flow is required to insure that the
sample loop is flushed clean of previous gases and contaminates. Constant
flow between all four sample loop positions is needed to reduce any systematic
problems with loading the sample loops. Below is a method for setting
sample flows:
- Shut down the data acquisition
software by pressing CTRL-C in the rungc screen and then typing "quit"
in the "chroms" screen.
- Start-up the "labdoit" program
by opening a new shell and typing labdoit. labdoit is a program very
similar to the standard data acquisition software but it does not do
injections. The operator also has control of the GC via the commands
at the bottom of the "chroms" screen.
- To check a flow, simply step
the stream selection valve (SSV) to the port of interest. You may have
to wait for up to a minute for the flow to register on the "chroms"
screen.
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Sample Stream
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Port #
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Cal 3 Solenoid
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Cal 1
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2
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Off
Always
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Air 1 or Cal 3
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4
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On
for Cal 3, Off
for Air 1
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Cal 2
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6
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Off
Always
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Air 2
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8
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Off
Always
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- To change a cal tank flow
rate, adjust the cal tank regulator pressure. To change the air flow
rate, adjust the back-pressure regulator on the pump board.
- Once all of the flows have
been set to approximately the same value quit the labdoit program. Simply
type quit in the "chroms" screen.
- To start the data acquisition
software again. Type "rungc" in an open shell window.
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