Varian 450-GC, User Manual

Page: 46 / 205

Installation
Varian, Inc. User Manual 450-GC Page: 27
Follow the steps below to set all gas flow rates on the 450-GC.
Flows are typically set with carrier gas first followed by detector make-up and
fuel gases. The most convenient way to measure or verify gas flows is at the
detector exit.
Adapters are provided in the individual detector accessory kits for this purpose.
Note, however, that the most accurate method to determine FID and TSD flows
is at the flame tip after removing the tower.
•
Attach a bubble or digital flowmeter to the detector outlet using the
appropriate adapter.
•
Turn off make-up and detector gases at the pneumatics panel. For a needle
valve this is accomplished by turning the needle valve cartridge knob fully
clockwise. For a flow controller this is accomplished by turning the flow
controller knob fully counter-clockwise or until the turns counting dial reads
zero.
•
Observe reading on flowmeter. Ensure it is within the range described in
the table for carrier gas flow rates.
•
Adjust the carrier gas flow using the manual pneumatics controls on the
pneumatics panel or by adjusting the Electronic Flow Control to achieve the
desired flow rate.
•
For a capillary system, turn on the make-up needle valve and adjust to
achieve the desired flow rate. The combined carrier and make-up flow
should be 30 mL/min. Adjustment is done with a small flat screwdriver
inside the needle valve cartridge knob.
•
Turn on the relevant detector fuel gases in the sequence hydrogen followed
by air. Use the table below to calculate the combined flows for the specific
detector. For the TSD adjust the hydrogen flow controller until the turns dial
reads 400.
Detector
C
make-up C make-up +
hydrogen C make-up +
hy air1 C make-up +
hyair1 + air2
FID 30 60 360
TSD 30 34 209
PFPD 2 15 32 42
Table 11: Detector manual Flow rates