Environnement MIR 9000 - LCD, Technical Manual

Page: 93 / 154

Duplication prohibited MIR 9000
3–55
February 2000
- Put the analyzer in calibration mode by pressing the
étalon
span
key and adjust the V1 valve to obtain an
excess flow of about 15 l/h, then allow the line to dry for at least 10 min.
TIG option: select the SPAN ANALYZER mode. Adjust the pressure of the pressure regulator valve
to 0.5 bars.
NH
3
/ H
2
O version: select the SPAN PROBE mode. Keep the flow at 200 l/h.
- Close the V2 valve and immediately inject the HCl or NH
3
by opening the span gas cylinder.
- Wait for the measurement to stabilise and if necessary modify the calibration coefficient.
- Close the span gas cylinder; open V2 to purge the line for about 10 min., put the analyzer into
measurement mode by pressing the
mesure
sample
, key; close V1 and the V2 and then close the bottle of
nitrogen (respecting the order given in this last point in order to maintain the injection plate under
pressure of the nitrogen).
TIG Option and MIR NH
3
/ H
2
O version: select the SPAN PROBE mode.
3.4.3.2 Calibration of HCl and NH
3
by comparison
The HCl and NH
3
calibrations can be made by comparing the measurement of the MIR 9000 with a
reference measurement.
This reference measurement may be a manual measurement or the measurement taken from an
automatic analyzer that had been calibrated previously.
A manual method for measuring HCl is standardised in France under N°NFX 43.309; this method is
being standardized in Europe (CEN).
The comparison method imposes the following elementary rules:
- The gas samples should have been made at the closest possible points, at all times ensuring that
the two samples are not perturbed.
- After stabilisation, the measurements will be integrated in a minimum period of 30 min.
- To validate the analyzer’s new calibration coefficient after modification (see below), two new
comparisons of the same duration as the previous one should be run to better results than :
Analyzer Measurement = Reference Measurement
±
5% or
±
5 mg/m
3
Calculation of the new calibration coefficient,
K
(new)
= K
(old)
* (Reference measurement / Analyzer measurement)