Reference
Page 32
User Manual Micro-GC
Varian, Inc.
MICRO ELECTRONIC GAS CONTROL (EGC)
The Micro-GC has built-in Micro EGC regulators that can be adjusted to get a constant
or programmed pressure control, which result in a constant or programmed flow through
the injector, column and detector. The pressure range of the Micro EGC is between 50-
350 kPa (7 - 49 Psi). This pressure sets a continuous flow of carrier gas of about 0.2-
4.0 mL/min.
A typical pressure rise is 200 kPa/min, which will give a significant pressure increase
during the run, without excessive baseline disturbance. In most cases baseline
subtraction may improve the quality of chromatograms that suffer from baseline drift.
INJECTOR
The injector has a built-in 10
l sample loop that is filled with the gaseous sample. The
pressure of the sample should be between 0-100 kPa (0-15 psi) and the sample
temperature within 5-40 °C ±5
C of the analyzer.
By start “Run” within the data-handling package, a vacuum pump will draw the gas
sample through the loop and then the injector will inject the gas sample from the sample
loop into the gas stream. The minimum pressure required by the injector is 550 kPa ±
10 % (80 psi ± 10 %). A typical injection time is 40 milliseconds (ms). This equals an
average injection volume of 200 nL. Injection time will be rounded to a multiple of 5 ms.
A practical minimum value is 40 ms.
In most cases a value of 0 - 20 milliseconds will result in no injection.
CARRIER GAS
GAS CLEAN UNIT
(OPTIONAL)
Micro-
electronic
gas control
(EGC)
Injector
Column &
reference
Detector
(TCD)
SAMPLE
IN
OUT
COLUMN/REFERENCE
VENT
Summary of Contents for Micro-GC 490-GC
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