M&C 1803436, Instruction Manual

Page: 24 / 53

24 PMA 50 EX | 1.01.04 www.mc-techgroup.com
18.1
ZERO CALIBRATION
To do a zero-point calibration of the analyzer, use an O2-free gas, e.g. nitrogen (N
2
) 5.0. Follow the steps
below:

Connect the flexible PVC or Viton tube with the bottle’s pressure reducer of the N
2
-zero gas bottle;
Warning
The pressure reducer should have a maximum outlet measuring range of 0 to
1.5 bar abs. and should always be adjusted to a low outlet pressure of max.
1.1 bar abs. This protects the measuring cell against destruction due to high
pressure!

First of all, open the bottle valve, then open the outlet valve of the pressure regulator;

The pressure regulator and the tubing have to be purged for about 5 seconds;

Check adjusted control pressure and reduce to ≤ 1.1 bar abs. if necessary, then shut-off the outlet valve of
the pressure regulator again;

Connect the free tube end of the zero gas bottle connection to the external flow meter or, if available, to
the external calibration valve;

Open the outlet valve of the pressure regulator slowly, in order to avoid pressure peaks;

Adjust the zero gas volume flow with the needle valve of the flow meter to max. 60 l/h. The volume flow
of the calibration gas should always be adapted to the sample gas volume flow;
Note
Always calibrate at the same gas flow as used for the measurement.

Wait approx. 30 seconds until display is stable;

Set the range switch 8 (see Figure 1) to 0-1 % O
2
(with a screw driver);

If necessary, adjust the zero point to 0 % via the zero point potentiometer 7 (Figure 1) (with a screw driver);

Check the analogue output signals at 0% O
2
;
Ouput signal Signal to be measured
0-10 V DC 0 V
0-20 mA 0 mA
4-20 mA 4 mA
Note
If a gas mixture is analyzed, the individual components shall be checked for possible
cross-sensitivity and taken into account accordingly during zero calibration (see chapter
20).

Shut the output valve of the pressure regulator and bottle valve and disconnect the tube connection to the
analyzer.