MIXCHEK
Setup
Teledyne
Analytical
Instruments
23
1.
With the air source still attached make sure the flow is
adjusted between 0.2 and 2 SLPM. Flow air for at least 2
minutes to purge all other gases from the sample line.
2.
After 2 minutes and with air still flowing in the sample line,
adjust the helium zero potentiometer on the front panel until
a reading on the helium display reads slightly above zero, for
instance, 4% helium.
3.
Slowly rotate the potentiometer and watch the helium display
as it slowly decreases toward zero. Once the helium reading
changes from 0.2% to 0.1% stop the adjustment process.
The analyzer is now properly zeroed.
Note: This procedure is necessary to avoid producing “negative”
readings. The display is incapable of displaying negative
values and will read zero even if the potentiometer is
turned additionally after the zero point is approached.
Span Calibration (helium sensor)
Note: The span is set using the helium display
1.
Attach the 100% helium gas to the sample inlet and adjust
the flow to between 0.2 and 2.0 SLPM.
2.
While helium is purging the sample line, watch the oxygen
display. When the oxygen concentration decreases to 0.2–0.0%,
adjust the helium span potentiometer on the front panel to set the
display (helium) to 100.0% ±0.2% helium.
The instrument is now calibrated
You should verify that the analyzer reads 20.9% O
2
and 00.0 ±0.2%
He with air flowing through the instrument and 0.00 ±0.2% O
2
and
100.0% ±0.2% He when flowing 100% He.
For additional calibration notes, see Section A.3 in the Appendix.
The analyzer is now ready to be placed in service.