Span Calibration - M&C PMA Series Instruction Manual

15.2

SPAN CALIBRATION

N O T E !
Before calibrating the span value, always check the zero point.
The following calibration procedure has to be carried out:

Adjust measuring range selection switch to the range in which the calibration will be carried out.

Connect the flexible PVC or Viton tube with the bottle pressure reducer of the test gas bottle, if nec-
essary with ambient air or instrument air.
W A R N I N G !

First open the bottle valve, then open the closed output valve of the pressure regulator;

Flush the pressure regulator and the tubing for about 5 seconds;

Check adjusted control pressure and reduce to ≤ 0.1 bar if necessary then shut the outlet valve of the
pressure regulator again.

Connect the free tube end of the test gas bottle connection with the gas inlet of the analyzer or, if
available, the external calibration valve;

Open slowly the output valve of the pressure reducer in order to avoid pressure peaks;

Set the test gas volume flow to approx. 50 l/h by means of the needle valve of the flow meter.
Always calibrate at the gas flow used for the measurement too.
N O T E !

Wait approximately 20 – 30 sec. until the indication has stabilised.

If necessary adjust span accurately according to the check gas concentration with a screw driver at
the span potentiometer 2 (figure 2) in the front panel. In case of air e.g. to 20.9 % O

Check the analog output signals:
24
In case the oxygen concentration of the sample gas is below 30 % O
the calibration can be performed with dry air. Should the concentra-
tions be higher, ideally, the test gas should correspond to the span
value!
The pressure reducer should have a maximum outlet measuring range
of 0-1.5 bar abs. and should always be adjusted to a low outlet pressure
of max. 0.1 bar. This protects the measuring cell against destruction due
to high pressure!
PMA30 | 1.01.03
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