M&C PMA Series User manual

Oxygen –Analyser Series PMA®
PMA 20
Instruction Manual
Version 1.00.01

2 PMA20 | 1.00.01 www.mc-techgroup.com
Content
1General information....................................................................................................................4
2Declaration of conformity...........................................................................................................4
3Safety instructions......................................................................................................................5
4Warranty......................................................................................................................................5
5Used terms and signal indications............................................................................................6
6Introduction................................................................................................................................. 7
6.1 Serial number...............................................................................................................7
7Application..................................................................................................................................7
8Technical data.............................................................................................................................8
9Description..................................................................................................................................9
9.1 Front panel.................................................................................................................10
9.2 Gas flow diagram of the analyser PMA 20...................................................................10
10 The measuring principle........................................................................................................... 11
11 Receipt of goods and storage..................................................................................................12
12 Installation.................................................................................................................................12
12.1 Connection of Sample gas inlet and sample gas outlet ................................................13
13 Standard gas conditioning system..........................................................................................13
14 Electrical connection................................................................................................................ 14
14.1 Signal output..............................................................................................................14
15 Starting up................................................................................................................................. 14
16 Calibration................................................................................................................................. 15
16.1 Zero calibration ..........................................................................................................15
16.1.1 Cross sensitivities................................................................................................17
16.1.2 Consideration of cross sensitivities ......................................................................18
16.2 Span calibration .........................................................................................................19
17 Measuring..................................................................................................................................21
18 Closing down ............................................................................................................................ 21
19 Maintenance..............................................................................................................................21
20 Trouble shooting.......................................................................................................................21
21 Spare parts list.......................................................................................................................... 22
22 Appendix ...................................................................................................................................22
List of Illustrations
Figure 1 Dimensions PMA20 ..............................................................................................9
Figure 2 Front panel PMA20.............................................................................................10
Figure 3 Gas flow diagram PMA 10...................................................................................10
Figure 4 Scheme of the measuring cell and optical signal processing ................................11
Figure 5 Standard gas conditioning system.......................................................................13
Figure 6 Electrical connection PMA 20..............................................................................14
Figure 7 Circuit diagram PMA 20 ......................................................................................23
Figure 8 Circuit diagram oxygen transducer unit PMA1.02.0..............................................24
Figure 9 Components list circuit diagram PMA1.02.0.........................................................25
Figure 10 Components list circuit diagram PMA1.02.0.........................................................26
Figure 11 Temperature sensor resistance dependent on temperature..................................27
Figure 12 Installation provisions and spare parts positions ..................................................28

www.mc-techgroup.com PMA20 | 1.00.01 3
Dear customer,
we have made up this operating manual in such a way that all necessary information about the
product can be found and understood quickly and easily.
Should you still have any question, please do not hesitate to contact M&C directly or go through
your appointed dealer. Respective contact addresses are to be found in the annexe to this operat-
ing manual.
Please also contact our homepage www.mc-techgroup.com for further information about our
products. There, you can read or download the data sheets and operating manuals of all M&C
products as well as further information in German, English and French.
This Operating Manual does not claim completeness and may be
subject to technical modifications.
© 04/2016 M&C TechGroup Germany GmbH. Reproduction of this doc-
ument or its content is not allowed without permission from M&C.
PMA®is a registered trade mark.
Version: 1.00.01

4 PMA20 | 1.00.01 www.mc-techgroup.com
HEAD OFFICE
M&C TechGroup Germany GmbH Rehhecke 79 40885 Ratingen Germany
Telephone: 02102 / 935 –0
Fax: 02102 / 935 –111
E - mail: [e-mail]
www.mc-techgroup.com
1 GENERAL INFORMATION
The product described in this operating manual has been examined before delivery and left our
works in perfect condition related to safety regulations. In order to keep this condition and to guar-
antee a safe operation, it is important to heed the notes and prescriptions made in this operating
manual. Furthermore, attention must be paid to appropriate transportation, correct storage, as well
as professional installation and maintenance work.
All necessary information a skilled staff will need for appropriate use of this product are given in
this operating manual.
2 DECLARATION OF CONFORMITY
CE - Certification
The product described in this operating manual complies with the following EU directives:
EMV-Instruction
The requirements of the EU directive 2014/30/EU “Electromagnetic compatibility“ are met.
Low Voltage Directive
The requirement of the EU directive 2014/35/EU “Low Voltage Directive“ are met.
The compliance with this EU directive has been examined according to DIN EN 61010.
Declaration of conformity
The EU Declaration of conformity can be downloaded from the M&C homepage or directly requested
from M&C.

www.mc-techgroup.com PMA20 | 1.00.01 5
3 SAFETY INSTRUCTIONS
Please take care of the following basic safety procedures when mounting, starting up or
operating this equipment:
Read this operating manual before starting up and use of the equipment. The information and
warnings given in this operating manual must be heeded.
Any work on electrical equipment is only to be carried out by trained specialists as per the regula-
tions currently in force.
Attention must be paid to the requirements of VDE 0100 (IEC 364) when setting high-power elec-
trical units with nominal voltages of up to 1000 V, together with the associated standards and
stipulations.
Check the details on the type plate to ensure that the equipment is connected to the correct mains
voltage.
Protection against touching dangerously high electrical voltages:
Before opening the equipment, it must be switched off and hold no voltages. This also applies to
any external control circuits that are connected.
The device is only to be used within the permitted range of temperatures and pressures.
Check that the location is weather-protected. It should not be subject to either direct rain or mois-
ture.
The device must not be used in hazardous areas.
Installation, maintenance, monitoring and any repairs may only be done by authorized personnel
with respect to the relevant stipulations.
4 WARRANTY
If the equipment fails, please contact M&C directly or else go via your appointed M&C dealer.
We offer a one year warranty as of the day of delivery as per our normal terms and conditions of
sale and assuming technically correct operation of the device. Consumables are hereby excluded.
The terms of the warranty cover repair at the factory at no cost or the replacement at no cost of
the equipment free ex user location. Reshipments must be sent in a sufficient and proper protective
packaging.

6 PMA20 | 1.00.01 www.mc-techgroup.com
5 USED TERMS AND SIGNAL INDICATIONS
DANGER!
This means that death, severe physical injuries and/or important ma-
terial damages will occur in case the respective safety measures are
not fulfilled.
WARNING!
This means that death, severe physical injuries and/or important
material damages may occur in case the respective safety
measures are not fulfilled.
CAUTION!
This means that minor physical injuries may occur in case the
respective safety measures are not fulfilled.
CAUTION!
Without the warning triangle means that a material damage may
occur in case the respective safety measures are not met.
ATTENTION
This means that an unintentional situation or an unintentional sta-
tus may occur in case the respective note is not respected.
NOTE!
These are important information about the product or parts of the
operating manual which require user’s attention.
SKILLED STAFF
These are persons with necessary qualification who are familiar
with installation, use and maintenance of the product.

www.mc-techgroup.com PMA20 | 1.00.01 7
6 INTRODUCTION
The M&C oxygen analyser PMA 20 is a temperature controlled instrument which has been de-
signed for continuous measurements of oxygen concentrations in particlefree and dry sample gas.
6.1 SERIAL NUMBER
The type plate with the serial number is in the lid of the analyser.
Whenever you call M&C regarding questions or orders for the spares please give us the serial
number of your PMA 20.
7 APPLICATION
Due to the extremely fast response time of the patented M&C magneto-dynamic measuring cell
with no stagnant volume as well as the negligible cross sensitivity from other sample gas compo-
nents, the M&C oxygen analyser PMA 20 has a wide variety of applications. The analyser is a
suitable and reliable instrument for monitoring oxygen concentrations in various gas analytical con-
trol applications including flue gas-, inert gas-, ambient air-, fermentation processes- and process
or laboratory control measurements.

8 PMA20 | 1.00.01 www.mc-techgroup.com
8 TECHNICAL DATA
Oxygen analyser Series PMA
Version PMA 20
Part No.
02A1000 = 230V 50Hz, 02A1000a = 115V 60Hz
Measuring ranges
selectable for 0-3, 0-10, 0-30 and 0-100 vol.% O2, linear
Indication
analogue meter with a scale of 0-30 and 0-100% for each selected
range
analogue meter with a scale of 0-30 and 0-100% for each selected
range, digital meter, 3 1/2 digit 9 mm high
for 0-100%O2reading, selectivity 0,1vol.% O2
Output signal
0-1V DC non-isolated, load > 100 KΩ, for the range of 100 vol.%,
and
0-20mA or 4-20mA* for the chosen range, non-isolated, max. load
300Ω
Response time for 90% FSD
< 3 seconds at 60 Nl/hr air
Accuracy after calibration
deviation: analogue = ± 1% of span / digital = ± 0,1 vol.% O2
Reproducibility deviation
analogue = < 1% of span / digital = ± 0,1 vol.% O2
Influence of ambient temperature
no influence up to 45 °C
Influence of barometric pressure
The oxygen reading varies in direct proportion to changes of the bar-
ometric pressure.
Influence of sample gas flow
variation in gas flow between 0-60 Nl/hr air will cause a difference of
< 0,1 vol.% O2.
Sample gas inlet pressure
0,01 up to 1 bar g, (PMA 20 required admission pressure for compe-
tent flow rate, no pump inside)
Sample gas outlet pressure
Outlet of analyser must discharge freely into atmosphere.
Flow rate of sample gas
max. 60 Nl/hr air, adjustable with needle valve on the flowmeter 7-70
Nl/hr
Temperature of sample gas
-10 °C up to +40 °C, dry gas
Analyser temperature
fixed at +50 °C
Ambient temperature
-10 °C up to +45 °C
Storage temperature
-20 °C up to +60 °C, relative humidity 0-90% RH
Power supply
internal power unit for 230VAC standard or 115VAC available (a)*
+/-10%, 40-60Hz, 26,5VA
Electrical connections
terminals 2,5 mm2; 1x PG11, 1x PG13,5 cable gland
Materials in contact with sample gas
Platinum, Glass, Polypropylene, Stainless Steel 316, FPM, Epoxy
resin
Sample gas connection
PP hose connectors DN 4/6 for 4 mm i.d. and 6 mm o.d. tube
Protection / electrical standard
IP 53 EN 60529 / EN 61010
Housing / colour
plastic wall mounting housing / blue/grey
Dimension / weight
height 220 mm, width 214 mm, length 182 mm / approx. 3 kg
Options
Extra charge for PMA 20 in solvent resistant version with special measuring cell type PMC-1LB.
Material: O-ring: Kalrez, flowmeter: PVDF, tubing and fittings: PVDF/SS316.
Extra charge for PMA 20 in chlorine resistant execution with a special measuring cell type PMC-
1CL2. All gas bearing tubes PTFE/PVDF equipped with purge gas connectors.
Extra charge for qualification test according to TA-Luft + EN 14181 resp. 13. and 17. BImSchV
Extra charge for PMA with combined analogue/digital display.
analogue meter with a scale of 0-30 and 0-100% for each selected range, digital meter, 3 1/2
digit 9 mm high
LCD-indicator for 0-100%O2 reading, selectivity 0,1vol.% O2or digital meter 3 1/2 digit 18 mm
high LCD for 0-100% O2reading, selectivity 0,1 vol.% O2

www.mc-techgroup.com PMA20 | 1.00.01 9
9 DESCRIPTION
The PMA 20 is a reliable and easy-to-operate instrument. It is built into a compact wall mounting
housing. The transducer unit maintains a constant operating temperature of 50 °C and a flashing
LED on the control panel indicates the proper operating temperature of the analyser. The four
measuring ranges are displayed on the analogue meter with 30/ 100% scale. Two output signals
are available. Sample gas connections as well as connectors for incoming power supply and output
signals are located inside the terminal box of the housing. The sample gas enters the analyser via
an external protective fine-filter. The required flow rate can be adjusted at the flowmeter with needle
valve, mounted on the front panel upstream the M&C measuring cell. The internal tubing is made
of FPM and PP. Option: ”TÜV certificate” or chlorine resistant version.
Figure 1 Dimensions PMA20

10 PMA20 | 1.00.01 www.mc-techgroup.com
9.1 FRONT PANEL
1
Analog indication
4
Flow meter
2
Zero potentiometer
5
Needle valve 7 - 70 Nl/hr
3
Span potentiometer
6
Measuring range selector switch
7
LED - heating control
Figure 2 Front panel PMA20
9.2 GAS FLOW DIAGRAM OF THE ANALYSER PMA 20

Fine filter

Measuring cell

Flow meter with needle valve
Figure 3 Gas flow diagram PMA 10

www.mc-techgroup.com PMA20 | 1.00.01 11
10 THE MEASURING PRINCIPLE
Oxygen is a gas with a significant paramagnetic susceptibility. The molecules of oxygen are at-
tracted much more strongly by a magnetic field than the molecules of other gases.
The measuring principle shown in the following is benefitting from these characteristics of the ox-
ygen. The great advantage of the paramagnetic measuring principle is the highly reduced cross
sensitivity of the measurement to other components in the sample gas.
Figure 2 shows the diagram of the measuring cell as well as the optical system for the detection of
the dumbbell’s movement.
2
4
3
1
GAS INLET
GAS OUTLET
7
8
5
6
9
Figure 4 Scheme of the measuring cell and optical signal processing
The measuring cell consists of two nitrogen-filled spheres which are arranged in the form of a
dumbbell. In the dumbbell’s central point of rotation, a small mirror is placed. The dumbbell is
surrounded by a wire coil needed for the compensation procedure. The described system is fixed
rotationally symmetrical inside a glass tube via a tightening strap out of platinum and is srewed
up with two pole pieces .
Two permanent magnets are producing an inhomogeneous magnetic field. When oxygen is flowing
in, the molecues of the oxygen are drawn into the magnetic field. In consequence, the lines of
electric flux on the cuneiform pole pieces are compressed. The nitrogen-filled diamagnetic
sheres are pushed out of the magnetic field. This causes a rotation of the dumbbell. The rotation
is detected via an optical system consisting of mirror , projection LED and photoelectric cell
.
In case the dumbbell is pushed out of the magnetic fieild, the tension of the photoelectric cell is
immediately changed. The measuring amplifiers and are producing a respective current which
develops via the wire coil on the dumbbell an electro-magnetic load moment. The load moment is
resetting the dumbbell into its zero position.

12 PMA20 | 1.00.01 www.mc-techgroup.com
Every change of the oxygen concentration produces a lineary proportional change of the compen-
sation current and can be read directly in % O2 as oxygen value on the display .
Due to its very small stagnant volume (2 cm3) and the direct flow of the M&C measuring cell, an
extremely fast response time (T90-time) of 1 second for a high gas flow can be realized.
11 RECEIPT OF GOODS AND STORAGE
The analyser PMA 20 is a completely pre-installed unit.
Please take the analyser and possible special accessories carefully out of the packaging mate-
rial immediately after arrival, and compare the goods with the items listed on the packing list;
Check the goods for any damage caused during delivery and, if necessary, notify your transport
insurance company without delay of any damage discovered.
NOTE!
The oxygen analyser PMA 20 must be stored in a wheather - pro-
tected and frost-proof area !
12 INSTALLATION
The PMA 20 is intended for stationary operation. In combination with a gas conditioning according
to the requirements a long lasting operability and a minimum of maintenance is guaranteed.
CAUTION!
The sample gas has to be dust free and dry to prevent a contam-
ination and condensation in the analyser.
Basically always connect a fine filter (e.g. type FP-2T, Part No.
01F1200) upstream.
CAUTION!
In case of outdoor operation protect the analyser against sun,
wind and rain.
At the installation location constant climatic ambient conditions
(pressure, temperature) are necessary to prevent a distortion of
the measurement and a condensation in the measuring cell in
case the ambient temperature is falling below the dew point tem-
perature of the sample gas.
A vibration-free location is ideal for mounting; if this is not pos-
sible, appropriate measures have to be taken. The analyser must
not be installed in direct proximity of heat sources.
The position of operation is not necessarily horizontal.
DANGER!
The analyser is allowed to be operated only in non-hazardous ar-
eas and with non-ignitiable gases and gas mixtures.
Mounting is done at the four exterior fixing holes (6mm) with adequate screws. Leave enough space
(approx. 120mm) at the right side of the housing for opening the housing in case of maintenance.

www.mc-techgroup.com PMA20 | 1.00.01 13
12.1 CONNECTION OF SAMPLE GAS INLET AND SAMPLE GAS OUTLET
The sample gas inlet and outlet are placed at the bottom side of the analyser and have tube con-
nections DN4/6mm.
Connect the sample gas inlet (rear connection) with a corresponding gas conditioning with
e.g. a PTFE hose DN4/6.
ATTENTION
Avoid back pressure in the sample gas outlet because an increase of pres-
sure will distort the oxygen indication.
Do not bend the connection hoses.
13 STANDARD GAS CONDITIONING SYSTEM


+5°C

PMA 20


Figure 5 Standard gas conditioning system
1: Heated gas sample probe (e.g. probe SP2000-H)
2: Heated gas sample line (e.g. 4M4/6)
3: Sample gas cooler (e.g. ECM-1G)
4: Peristaltic pump or condensate collecting vessel (e.g. SR25.1 or TG-1)
5: Diaphragm pump (e.g. N3)
6: Fine filter (FP-2T)

14 PMA20 | 1.00.01 www.mc-techgroup.com
14 ELECTRICAL CONNECTION
The electrical connection is done at the terminals in the connection box below the analyser:
Loosen the two screws of the lid end remove it.
CAUTION!
False supply voltage can damage the equipment. When connect-
ing the equipment, please ensure that the supply voltage is iden-
tical with the information provided on the model type plate!
Power SW1 Signal output
PE
L
N
X1
Figure 6 Electrical connection PMA 20
Lead power cable with wire cross section 2,5mm2through the left cable gland with clamping
range 8-12mm cable diameter and connect according to figure 6 at terminal X1.
Check wether service-power-switch (SW1), which is located to the left of terminal X2, is in
position 1 (left position).
14.1 SIGNAL OUTPUT
The PMA 20 has two signal outputs as standard. One signal is 0-1V for 100% O2(independent of
the chosen measuring range). The second signal is 0-20 or 4-20mA according to the order with a
burden of 500Ohm for each measuring range. The output signals are not galvanically isolated.
Lead signal cable with wire cross section 1,5mm2through the right cable gland with clamp-
ing range 6-8mm cable diameter and connect according to figure 6 at terminal X2.
Remount lid.
15 STARTING UP
Check electrical connections and gas connections.
Turn measuring range selection switch from „0“ to the desired measuring range. The ana-
lyser is ready for operation immediately.
Check mechanical zero of the indication; if necessary adjust zero position by turning the
slotted screw in the pane of the indication instrument.
Turn measuring range selection switch to 30%.
Switch on mains voltage.
The indication instrument shows 21% O2with ambient air in the measuring cell and the LED
for heater control lights up permanently.
0
+
0
+
mA
mV
X2

www.mc-techgroup.com PMA20 | 1.00.01 15
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 cal-
ibration.
16 CALIBRATION
The accuracy of an analyser mainly is dependent on its calibration.
NOTE!
Before calibration it has to be assured that the calibration conditions cor-
respond to the conditions during measurement. The flow rate and the bar-
ometric pressure conditions have to be constant. Under this terms a cali-
bration of the analyser is necessary aproximately one time a week to main-
tain the accuracy. If flow rate or barometric pressure conditions are chang-
ing 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 (N25.0) is used.
For span calibration with M&C O2-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 sufficient.
For measurement concentrations > 40% O2a 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 N2-zero-gas bottle.
The pressure reducer should have an output control range of max. 0 –1,5 bar abs..
CAUTION!
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 reducer
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.
NOTE!
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 % O2with a screw driver at the zero potentiometer
in the front panel

16 PMA20 | 1.00.01 www.mc-techgroup.com
Check output signals at 0,0% O2:
NOTE!
If a gas mixture is analysed, the single gas components have to be checked
concerning potential cross sensitivity and regarded for zero calibration. (see
chapter 16.1.1 and 16.1.2).
Shut off pressure outlet valve and bottle valve.
Disconnect hose connection from the analyser.
Zero calibration is finished.
NOTE!
After zero calibration the span has to be calibrated too.
Output signal
Measurement
0-1 V
0 V
0-20 mA
0 mA
4-20 mA
4 mA

www.mc-techgroup.com PMA20 | 1.00.01 17
16.1.1 CROSS SENSITIVITIES
The following table shows the cross sensitivities of the most important gases at 20°C and 50°C. All
values are based on a zero calibration with N2and a span calibration with 100 Vol.% O2. The
deviations are each valid for 100 Vol.% of the respective gas.
Gas Molecular formula 20°C 50°C
Acetaldehyde C2H4O - 0,31 - 0,34
Acetone C3H6O - 0,63 - 0,69
Acetylene C2H2- 0,26 - 0,28
Ammonia NH3- 0,17 - 0,19
Argon Ar - 0,23 - 0,25
Benzene C6H6- 1,24 - 1,34
Bromine Br2- 1,78 - 1,97
Butadiene C4H6- 0,85 - 0,93
n-Butane C4H10 - 1,10 - 1,22
Iso Butylen C4H7 -0,94 - 1,06
Chlorine Cl2- 0,83 - 0,91
Diacetylene (CHCl)2- 1,09 - 1,20
Nitrous monoxide N2O - 0,20 - 0,22
Ethane C2H4- 0,43 - 0,47
Ethylbenzene C8H10 - 1,89 - 2,08
Ethylene C2H4- 0,20 - 0,22
Ethylene glycol (CH2OH)2- 0,78 - 0,88
Ethylene oxide C2H4O2- 0,54 - 0,60
Furan C4H4O - 0,90 - 0,99
Helium He + 0,29 + 0,32
n-Hexane C6H14 - 1,78 - 1,97
Hydrogen chloride HCL - 0,31 - 0,34
Hydrogen fluoride HF + 0,12 + 0,14
Hydrogen sulfide H2S - 0,41 - 0,43
Carbon dioxide CO2- 0,27 - 0,29
Carbon monoxide CO - 0,06 - 0,07
Krypton Kr - 0,49 - 0,54
Methane CH4- 0,16 - 0,17
Methanol CH4O - 0,27 - 0,31
Methylen chloride CH2Cl2- 1,00 - 1,10
Methyl propene C4H8- 0,94 - 1,06
Monosilan SiH4- 0,24 - 0,27
Neon Ne + 0,16 + 0,17
n-Octane C8H18 - 2,45 - 2,70
Phenol C6H6O - 1,40 - 1,54
Propane C3H8- 0,77 - 0,85
Propylene C3H6- 0,57 - 0,62
Propylene chloride C3H7Cl - 1,42 - 1,44
Propylene oxide C3H6O - 0,90 - 1,00
Oxygen O2+100,00 +100,00
Sulfur dioxide SO2- 0,18 - 0,20
Sulfur fluoride SF6- 0,98 - 1,05
Monosilane SiH4 -0,24 - 0,27
Nitrogen N20,00 0,00
Nitrogen dioxide NO2+ 5,00 + 16,00
Nitrogen monoxide NO + 42,70 + 43,00
Styrene C8H8- 1,63 - 1,80
Toluene C7H8- 1,57 - 1,73
Vinyl chloride C2H3Cl - 0,68 - 0,74
Vinyl fluoride CH3F - 0,49 - 0,54
Water (Steam) H2O - 0,03 - 0,03
Hydrogen H2+ 0,23 + 0,26
Xenon Xe - 0,95 - 1,02

18 PMA20 | 1.00.01 www.mc-techgroup.com
16.1.2 CONSIDERATION OF CROSS SENSITIVITIES
The selectivity of the above mentioned measuring principle is based on the high susceptibility of
oxygen to other gases (see table).
The following examples shall show how cross sensitivities can be considered for the zero calibra-
tion.
Example 1: Determination of the rest content of oxygen in a 100% carbon dioxide
(CO2) protective atmosphere at 20°C
In the table of cross sensitivities you can read the value for CO2 at 20°C of –0,27. This means that
for calibration with nitrogen the zero point must be set to +0,27% in order to compensate the devi-
ation of the display.
In this example, the atmosphere contains exclusively CO2and O2. For this reason, the influence of
cross sensitivity can be eliminated without problem by using carbon dioxide (CO2) instead of nitro-
gen for the zero calibration.
Example 2: Determination of the oxygen content of a gas mixture at 20°C
1 Vol.% C2H6(Ethane);
5 Vol.% O2;
40 Vol.% CO2;
54 Vol.% N2.
Zero point calibration with nitrogen (N2).
The cross sensitivity values of above table are based on 100 Vol.% of the respective gases. There-
fore, a conversion must be maid to the effective volume concentration. In principle, the following is
valid:
Table value * Volume concentration
Effective cross sensitivity =  [Vol.%]
100
For the components of the gas mixture, the following values are found:
C2H6 : -0,0043 Vol.%;
CO2 : -0,1080 Vol.%;
N2 : 0,0000 Vol.%.
= -0,1123 Vol.%
To determine the sum of cross sensitivity as exactly as possible, a correction factor has to be
determined, because the sum of cross sensitivities relates not on 100% but on 100% minus the
oxygen concentration (here 95%).

www.mc-techgroup.com PMA20 | 1.00.01 19
The correction factor is calculated as follows:
100
Correction factor = 
(100 –O2-concentration)
It is incidental:
100
 = 1,0526
(100 –5)
For the gas mixture the rectified sum cross sensitivity then is calculated in good approximation:
1,0526 x -0,1123 Vol.% = -0,1182 Vol.%
The rectified sum cross sensitivity with change of sign now can be used for the correction of the
zero calibration. In this case zero had to be adjusted at +0,1182 Vol.%.
In case the cross sensitivities should be ignored in the above mentioned example, this would result
in a relative error of approximately 2%.
NOTE!
After zero calibration the span has to be calibrated too.
16.2 SPAN CALIBRATION
Before span calibration a finished zero calibration is necessary.
Turn the measuring range selection switch to the measuring range in which the calibration
should be done. In case of measuring value concentrations <30% O2a calibration with dry
clean air in the range of 30% O2is recommended. Turn the measuring range selection
switch to 30%. In case of measuring value concentrations >40% O2 a calibration in the
100% range with adequate test gas is recommended. Turn the measuring range selection
switch to 100%.
Connect a flexible PVC- or FEP-hose with the pressure reducer of the N2-zero-gas bottle.
The pressure reducer should have an output control range of max. 0 –1,5 bar abs..
CAUTION!
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 reducer
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.

20 PMA20 | 1.00.01 www.mc-techgroup.com
Connect the hose end of the instrument air or check 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.
NOTE!
Always calibrate at the flow rate that is adjusted for the measurement
too.
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 in the front panel. In case of air e.g. to 20,9 % O2.
Check output signals at 20,9% O2:
Shut
off pressure
reducer
valve and
bottle- resp. Instrument air valve resp. integrated sample gas pump.
Disconnect hose connection at the analyser.
Determination of the output signal:
(Se–Snp) V resp. mA x gas concentration Vol % O2
upper range value Vol % O2
Se = Final value, signal output
Snp = Zero, signal output
Shut off pressure reducer output valve and bottle valve. Druckreglerausgangsventil und Fla-
schenventil schließen.Disconnect hose connection at the analyser.
The span calibration is finished.
NOTE!
If during the span calibration great variations have to be compensated
(>2% O2) at the potentiometers, a second zero and span calibration is
reasonable.
ATTENTION
After finishing the calibration turn measuring selection switch to the de-
sired measuring range.
The mA-output signal is dependant on the measuring range!
Output signal
Measurement
range 100 % O2
Measurement
range 30 % O2
0-1 V
0,209 V
0,697 V
0-20 mA
4,18 mA
13,93 mA
4-20 mA
7,34 mA
15,15 mA
+ Snp