Teledyne 2120 - Trace Nitrogen in Argon Analyzer - Manual (Page 42)

Operation Model 2120
cylinder with a low ppm nitrogen level can be used for zeroing in the
low ppm range specified, as long as the N
2
concentration is known.
The second point is fixed by a certified span gas normally supplied
in a high-pressure cylinder.
4.2.3 Calibration Steps
Note: The zero, span, and sample gas should all be supplied to
the analyzer at the same flow rate, 2 cfh (940 ccpm). The
Analyzer flow and pressure are controlled by a sample inlet
orifice. Use the regulator at the sample, span, or zero gas
source to adjust flow while monitoring the flowmeter on the
front panel.
To calibrate the instrument:
1. Set the ZERO potentiometer to 2.00 and SPAN potentiometer to
8.00. (If zero and span settings from a previous calibration are
known, these may be used in place of 2.00 and 8.00.)
2. Connect a DC millivoltmeter across the Test Points on the rear
panel.
Note: To preserve calibration accuracy, cylinder pressure for the
calibration standard gases should not fall below 500 psig
(3447 kPa).
3. Flow span calibration gas to the analytical cell at a rate of 2 cfh
(940 ccpm) as determined from the sample flowmeter on the
front panel.
4. Plate Adjustments:
For the 0-200 ppm range: Adjust the plate adjustment
potentiometer on the rear panel to obtain a reading in
mVDC equal to 0.7 times the span calibration gas in ppm
(i.e., with a span gas of 180 ppm, the millivolt reading
should be 126 mVDC).
For the 0-20 ppm range: Adjust the plate adjustment
potentiometer on the rear panel to obtain a reading in
mVDC equal to 7 times the span calibration gas in ppm
(i.e., with a span gas of 18.0 ppm, the millivolt reading
should be 126 mVDC).
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Teledyne Analytical Instruments