6 – Calibration
MultiExact Gas Analyser
6.3
Calibrating the pressure transducer (O
2
purity only)
CAUTION
On a pressure driven analyser, do not exceed the specified maximum
calibration gas inlet pressure, and on a flow driven analyser, do not exceed
the specified maximum flow rate. If you do, the pressure transducer may be
damaged and the analyser may not operate correctly.
CAUTION
You must perform low and high measurement calibration (as described in
Section 6) before you calibrate the pressure transducer. The flow rate
through the analyser must be kept constant for both the low and high
pressure calibration points.
If you use pressure compensation (see Section 7.2), you must calibrate the pressure
transducer when you first calibrate the analyser, and annually thereafter.
Calibrate the pressure transducer as follows:
1.
Calibrate the analyser as described in Section 6.
2.
Temporarily fit a suitable adjustable valve (such as a needle valve) and a
flowmeter to the sample gas outlet (see Figure 2).
3.
If the auto validation/calibration option is fitted, the high calibration gas will
automatically be selected during calibration. Otherwise, connect the high
calibration gas supply to the sample gas inlet pipe on the analyser.
4.
Fully open the adjustable valve (that is, so that the pressure at the outlet is
ambient atmospheric pressure).
5.
Select
➞
Service
➞
Pressure.
6.
Allow the O
2
measurement shown on
the screen to stabilize (for at least
30 seconds), then take a note of the
calibration gas flow rate and press
the
soft key, ensure low
calibration concentration is greater
than 95% and less than 105%.
Figure 85 – The pressure low
calibration screen
72
05410001A / Revision 6