M&C TechGroup PMA 20 Operator's manual - Manual (Page 15)

15
Gas sampling and gas conditioning technology 9-3.5.1-ME

After approximately 30 min. the LED in the indication instrument starts flashing. After 12
hours the transmitter has reached a temperature balance and the analyser is ready for c a-
libration.
16 CALIBRATION
The accuracy of an analyser mainly is dependent on its calibration.
N O T E !
Before calibration it has to be assured that the calibration conditions cor-
respond to the conditions during measurement. The flow rate and the
barometric pressure conditions have to be constant. Under this terms a
calibration of the analyser is necessary aproximately one time a week to
maintain the accuracy. If flow rate or barometric pressure conditions are
changing significantly, a new calibration is necessary.
During calibration the device must not be exposed to vibrations.
For zero calibration of the analyser an oxygen-free gas, mostly nitrogen (N
2
5.0) is used.
For span calibration with M&C O
2
-analysers it is possible to abandon on special test gas mixtures
because of the measuring principle and the linear measuring ranges. Dry and clean air is suffi-
cient. For measurement concentrations > 40% O
2
a calibration with corresponding test gas could
be possibly recommandable.
16.1 ZERO CALIBRATION

Connect a flexible PVC- or FEP-hose with the pressure reducer of the N
2
-zero-gas bottle.
The pressure reducer should have an output control range of max. 0 – 1,5 bar abs..
C A U T I O N !
The outlet pressure is only allowed to be adjusted at max. 0,1 bar. Other-
wise the measuring cell of the analyser will be destroyed.

Open the bottle valve and than the closed pressure reducer outlet valve and purge the
pressure reducer and the complete hose line for approximately 5 sec. the pressure reduc-
er and the complete hose line.

Check the adjusted control pressure and reduce if necessary to ≤ 0,1bar, then shut off the
pressure reducer valve again.

Connect the hose end of the zero-gas bottle connection to the gas inlet of the analyser.

Open the pressure reducer valve slowly, to avoid pressure peaks.

Adjust the flow rate to 50 Nl/hr at the flow meter.
N O T E !
Always calibrate at the flow rate that is adjusted for the measurement
too.

Wait approximately 20
– 30 sec. until the indication has stabilised.

Turn measuring range selection switch to position 3%

If necessary adjust zero accurately to 0 % O
2
with a screw driver at the zero potentiometer
in the front panel