Calibration; Zero Point Adjustment - M&C PMA Series Instruction Manual

16

CALIBRATION

The preciseness of an analyzer depends to an important extent on its calibration.
N O T E !
For the zero point calibration of the analyzer, an oxygen-free gas – in most times nitrogen (N
used as zero gas.
Regarding the sensitivity adjustment, no special test gas mixtures are necessary due to the measuring
principle and the linearly measuring ranges of the M&C O
For measuring value concentrations of > 40 % O
with a respective test gas.
16.1

ZERO POINT ADJUSTMENT

Connect a flexible PVC or Viton tube with the pressure reducer of the N
•
The pressure reducer should have got an output range of adjustment of max. 0 – 1.5 bar.
Open the cylinder valve first and then open the closed output valve of the pressure con-
•
troller. Purge the pressure controller including the tubes for approx. 5 seconds.
Check the adjusted pressure and reduce it if necessary to ≤ 0.1 bar, then close the output
•
valve of the pressure controller again.
• Connect the free tube end of the zero gas bottle connection to the gas inlet of the analyzer
or – if existing – to the external calibration valve.
• Open slowly the pressure controller output valve in order to avoid pressure peaks.
Adjust the flow at approx. 50 l/h on the flowmeter.
•
N O T E !
Wait approx. 20 - 30 seconds until the indication is stable.
•
• Turn the measuring range selector switch (4, see figure 2) in position 2.5 %.
If necessary, adjust the zero point with a screw driver to exactly 0 % O
•
potentiometer (5, see figure 2) on the bottom side of the housing.
Check the signals of the recorder output at 0.0% O
•
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Before executing a calibration, it must be assured that the calibration
conditions correspond to the conditions during the measurements. The
flow quantity and the barometric pressure conditions must be constant.
Under these conditions, a calibration of the analyzer becomes necessary
nearly once a week in order to keep the exactness. Should there, howev-
er, be a considerable change of the flow quantity or the barometric pres-
sure conditions, a new calibration is necessary.
During the calibration, the instrument must not be exposed to any vibra-
tions.
Always calibrate with the same gas quantity that is taken for measure-
ment.
Recorder output signal
0-10 V
0-20 mA
4-20 mA
analyzers. Dry and clean air is sufficient.
2
, it may be recommendable to make a calibration
2
:
2
Measured
value
0 V
0 mA
4 mA
PMA45K1 | 1.00.01
5.0) is
2
zero gas bottle.
2
on the zero point
2
17