M&C PMA Series User manual

Oxygen Analyzer Series PMA
®
PMA 50 EX
(Effective from: March 2018,
Serial No. 1803436)
Instruction Manual
Version 1.01.04

2 PMA 50 EX | 1.01.04 www.mc-techgroup.com
Dear customer,
Thank you for buying our product. In this instruction manual you will find all necessary information about this
M&C product. The information in the instruction manual is fast and easy to find, so you can start using your M&C
product right after you have read the manual.
If you have any question regarding the product or the application, please don’t hesitate to contact M&C or your
M&C authorized distributor. You will find all the addresses in the appendix of this manual.
For additional information about our products and our company, please go to M&C’s website www.mc-
techgroup.com. There you will find the data sheets and manuals of our products in German and English.
T
his instruction manual does not claim completeness and may be subject
to technical modifications.
© 04/2022 M&C TechGroup Germany GmbH. Reproduction of this document or
its content is not allowed without permission from M&C.
PMA
®
is a registered trade mark.
T
he German instruction manual is the original instruction manual.
Version: 1.01.04

www.mc-techgroup.com PMA 50 EX | 1.01.04 3
List of Contents
1General information ............................................................................................................................. 5
2Declaration of conformity.................................................................................................................... 5
3Electrical standards............................................................................................................................... 6
4Safety instructions ................................................................................................................................ 6
4.1 Proper Use ....................................................................................................................................................................................7
5Information and safety instructions for using the Analyzer in hazardous areas ......................... 7
5.1 Analyzing gases from Ex zone II 1G Ex IIC T4.....................................................................................................7
6Warranty ................................................................................................................................................. 8
7Used terms and signal indications...................................................................................................... 8
8Introduction ......................................................................................................................................... 10
8.1 Serial number...........................................................................................................................................................................10
8.2 Power supply............................................................................................................................................................................10
9Application........................................................................................................................................... 10
10 Technical Data ..................................................................................................................................... 11
10.1 Options........................................................................................................................................................................................12
11 Description........................................................................................................................................... 13
11.1 PMA 50 Ex/P/PD-1-50 with pressure compensation and enclosure purging (without SIL-
certification)..............................................................................................................................................................................14
11.2 PMA 50 Ex/P/PD with pressure compensation (without SIL-certification) ................................................15
11.3 Option zero suppression (without SIL-certification).............................................................................................15
11.4 Option enclosure purging or enclosure ventilation .............................................................................................15
12 Measuring principle ............................................................................................................................ 15
13 Gas flow diagram................................................................................................................................. 17
14 Receipt of goods.................................................................................................................................. 19
15 Installation ........................................................................................................................................... 19
16 Supply connections............................................................................................................................. 20
16.1 Sample gas inlet and sample gas outlet.....................................................................................................................20
16.2 Option purging enclosure or enclosure ventilation .............................................................................................21
16.3 Electrical connection............................................................................................................................................................22
17 Starting up ........................................................................................................................................... 23
18 Calibration............................................................................................................................................ 23
18.1 Zero calibration.......................................................................................................................................................................24
18.2 Full scale value calibration.................................................................................................................................................25
19 Measuring............................................................................................................................................. 27
20 Cross sensitivities................................................................................................................................ 28
21 Closing down ....................................................................................................................................... 31
22 Storage and Transport........................................................................................................................ 31
23 Maintenance ........................................................................................................................................ 31
23.1 Removal of the measuring cell........................................................................................................................................33
23.2 Mechanical zero point adjustment................................................................................................................................36
24 Proper disposal of the device ............................................................................................................ 37
25 Spare parts list ..................................................................................................................................... 37
26 Appendix .............................................................................................................................................. 38

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List of Illustrations
Figure 1 PMA50 EX oxygen analyzer .........................................................................................................................................13
Figure 2 Drawing of the measuring cell and optical signal processing...................................................................16
Figure 3 Gas flow diagram .............................................................................................................................................................17
Figure 4 Gas conditioning ..............................................................................................................................................................18
Figure 5 Dimensions for installation..........................................................................................................................................19
Figure 6 Electrical connection inside the connection box of the PMA50 EX........................................................22
Figure 7 Drawing of the internal analyzer design...............................................................................................................33
Figure 8 Transmitter unit ...................................................................................................................................................................35
Figure 9 Transmitter unit for mechanical zero point adjustment...............................................................................36
Figure 10 Circuit diagram front board PMA50 EX .................................................................................................................41
Figure 11 Assembly front board PMA50 EX..............................................................................................................................42
Figure 12 Circuit diagram mains adapter PMA50 EX ...........................................................................................................43
Figure 13 Assembly/connection mains adapter PMA50 EX .............................................................................................44
Figure 14 Cut-out magnification front board for adjustment of temperature alarm (TP10, P19) (TP11:
current temperature) und flow alarm threshold (P20)....................................................................................45
Figure 15 Cut-out magnification front board couple sensor bridge for application of a transmitter
without couple sensor....................................................................................................................................................45
Figure 16 Cut-out magnification front board for adjustment of reference voltage , amplification and
offset of the O2-signal .....................................................................................................................................................46
Figure 17 Cut-out magnification mains adapter for adjustment of the temperature, current and
voltage output....................................................................................................................................................................47
Figure 18 Cut-out magnification mains adapter for adjustment of burden and limitation of the
current output ....................................................................................................................................................................47

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Head Office
M&C TechGroup Germany GmbH Rehhecke 79 40885 Ratingen Germany
Telephone: 02102 / 935 - 0
Fax: 02102 / 935 - 111
E - mail: [email protected]
www.mc-techgroup.com
1 GENERAL INFORMATION
The product described in this instruction 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 guarantee a safe oper-
ation, it is important to heed the notes and prescriptions made in this instruction manual. Furthermore, at-
tention 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 instruc-
tion manual.
2 DECLARATION OF CONFORMITY
CE - Certification
The product described in this instruction manual complies with the following EU directives:
ATEX-Directive
The product described in this manual is produced in accordance with the EU directive for devices and protection
systems for appropriate use in hazardous areas 2014/34/EU appendix II.
RoHS Directive
The requirements of the RoHS2 (‘Restriction of Hazardous Substances 2’) directive 2011/65/EU and its an-
nexes are met.
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.
The SIL –declaration of conformity can be requested directly at M&C.

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3 ELECTRICAL STANDARDS
The electrical standard of electrical equipment corresponds to the safety regulations concerning the EN61010
and to the safety requirements of the European standards:
EN 61010
EN 61508
EN 60079-0:2012+A11:2013
EN 60079-1:2014
EN 60079-7:2015
for operation of the equipment in hazardous areas group II category 2. Attention must be paid to the Certifi-
cate of Conformity IBExU 16 ATEX 1192 (see appendix).
4 SAFETY INSTRUCTIONS
Note the following basic safety procedures when using this equipment:
Read these operating instructions carefully before start-up and use of the equipment! The infor-
mation and warnings given in these operating instructions must be heeded.
Attention must be paid to the requirements of the certificate of conformity (see appendix): IBExU 16
ATEX 1192.
Work on electrical equipment is only to be carried out by trained specialists as per the regulations
currently in force.
Attention must be paid to the requirements of VDE 0100 when setting high-power electrical units
with nominal voltages of up to 1000 V, together with the associated standards and stipulations.
For use in hazardous area observe the relevant national and international instructions and regula-
tions.
Check the details on the type plate to ensure that the equipment is connected up to the correct
mains voltage.
Protection against touching dangerously high electrical voltages. Before opening the equipment, it
must be switched and hold no voltages. This also applies to any external control circuits that are
connected.
The equipment is only to be set within the permitted range of temperatures and pressures.
Check that the location is weather-protected. It should not be subjected to either direct sun, rain or
moisture.
Installation, maintenance, monitoring and any repairs may only be done by authorised personnel
with respect to the relevant stipulations.

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4.1 PROPER USE
The oxygen analyzer PMA50 EX is suitable for analyzing gas mixtures classified in Zone 1 with an oxygen
content of up to 21% by volume. The PMA50 EX is suitable for the continuous measurement of oxygen in
particle-free and dry sample gases with a maximum dew point of 5 °C [41 °F].
Only install and operate the analyzer under the operating parameters and conditions described in chapter 5
“Information and safety instructions for using the Analyzer in hazardous areas” and chapter 10 “Technical
Data” of this instruction manual.
Refrain from all uses other than for this purpose. Improper use can lead to serious injuries, for more details
see the safety instructions at the appropriate place.
5 INFORMATION AND SAFETY INSTRUCTIONS FOR USING THE ANALYZER
IN HAZARDOUS AREAS
The Oxygen Analyzer PMA 50 Ex is suitable for use in hazardous area group II category 2.
The explosion proof protection is:
II 2G Ex d b eb IIC T4 Gb IBExU 16 ATEX 1192 , IECEx IBE 16.0041
The oxygen analyzer PMA50 EX is suitable for analyzing gas mixtures classified in Zone 1 with an oxygen content
of up to 21% by volume.
Higher oxygen concentrations are not covered by the ATEX directive.
The analyzer has been certified through IBExU, authorized company for official approval of electric equipment in
the Netherlands. Detailed information and a copy of the certificate are attached to this instruction manual.
Installation and operation of the analyzer has to be done corresponding to the conditions in the Ex-certificate (see
appendix). Only in this case, the reliability of operation in hazardous area can be guaranteed.
All changes of the standard analyzer with parts which are not specified or approved by M&C as well as repair and
service with not specified parts mean a loss of the Ex-certificate.
In case of doubt, please turn directly to M&C respectively to your M&C franchised dealer.
5.1 ANALYZING GASES FROM EX ZONE II 1G EX IIC T4
T wo protective devices must always be used for category 1G.
In both, the measuring gas inlet and outlet of the analyzer PMA50 EX, a M&C breathing and draining device
MC95A EX II 2G Ex db IIC Gb is mounted.
When using explosive gas mixtures, which require zone 0, a suitable protection system must be provided in both
the inlet and outlet against flame flashback.
The entire body has to be made of stainless steel.
Alternatively, other suitable protective devices against flame flashback can be used.

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6 WARRANTY
If the equipment fails, please contact M&C directly or else go through your M&C authorised 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 unit. Consumables are hereby excluded. The terms of the war-
ranty 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.
7 USED TERMS AND SIGNAL INDICATIONS
Danger
This means that death, severe physical injuries and/or important material dam-
ages 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 status may oc-
cur in case the respective note is not respected.
Note
These are important information about the product or parts of the instruction
manual which require user’s attention.
Qualified personnel ‘Qualified personnel’ are experts who are familiar with the installation, com-
missioning, maintenance, and operation of these types of products. The fol-
lowing knowledge is at least required for the work:
Instructed person in EX-protection
Trained person in the electrotechnical field
Detailed knowledge of the manual and the applicable safety regulations
‘Ex‘ indicates important information about the product or about the corre-
sponding parts in the instruction manual, relating to usage in potentially ex-
plosive atmospheres.

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High voltages!
Protect yourself and others against damages which might be caused by
high voltages.
Corrosive!
These substances destroy living tissue and equipment upon contact.
Do not breathe vapors; avoid contact with skin and eyes.
Hot surface!
Contact may cause burn! Do not touch!
Wear protective gloves!
Working with chemicals, sharp objects or extremely high temperatures re-
quires wearing protective gloves.
Wear safety glasses!
Protect your eyes while working with chemicals or sharp objects. Wear
safety glasses to avoid getting something in your eyes.
Wear protective clothes!
Working with chemicals, sharp objects or extremely high temperatures re-
quires wearing protective clothes.

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8 INTRODUCTION
8.1 SERIAL NUMBER
The type plate with the serial number is fixed on the left side of the analyzer’s housing.
Please indicate always this serial number in case of questions or when purchasing spare parts.
8.2 POWER SUPPLY
The internal power supply of the oxygen analyzer PMA50 EX is 115 V or 230 V AC, 40 - 60 Hz. Detailed infor-
mation can be found on the type plates. Variations of the power supply of -15 % to +10 % do not effect the
function of the analyzer.
9 APPLICATION
The Oxygen Analyzer PMA 50 EX is suitable for the continuous measurement of oxygen in particle-free and
dry sample gases with a maximum dew point of 5 °C [41 °F].
The features of the analyzer are safe operation, accuracy and low maintenance.
The measurement is based on the physical principle of the paramagnetic oxygen measuring cell and is one
of the most exact quantitative methods of oxygen determination within the range of 0-100 vol% oxygen.
There is a direct flow against the measuring cell which has got a low volume of only 2 ml (small stagnant
volume). Further characteristics are robustness, extremely small drift, fast response time (T90 < 5 sec.) and
negligible cross sensitivities to other sample gas components.
Fluctuations of the flow rate in a range from 0 Nl/h to 60 Nl/h air cause a change of the oxygen reading which
is smaller than 0.2 vol% O2.
Measurements in flue gas and in inerting plants are among many other measurement tasks which are typical
applications for the PMA 50 EX.

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10 TECHNICAL DATA
Part Number
05A1000 PMA 50 EX, power supply 230 V, pressure range 0.6 to 1.1 bar abs.
05A1000a PMA 50 EX, power supply 115 V, pressure range 0.6 to 1.1 bar abs.
05A2500 PMA 50 EX/P/PD-1-50, power 230 V, (not with SIL-certification)
pressure compensation 0.6 to 1.5 bar abs. with purging the enclosure via two
breathing and draining devices in the in- and outlet 1/4“ NPT female
05A2500a PMA 50 EX/P/PD-1-50, power 115 V, (not with SIL-certification)
pressure compensation 0.6 to 1.5 bar abs. with purging the enclosure via two
breathing and draining devices in the in- and outlet 1/4“ female
05A2505 PMA 50 EX/P/PD, power 230 V, (not with SIL-certification)
pressure compensation 0.6 to 1.1 bar abs.
05A2505a PMA 50 EX/P/PD, power 115 V, (not with SIL-certification)
pressure compensation 0.6 to 1.1 bar abs.
Power supply 230 V AC (standard) or 115 V AC (a) -15 % to +10 %, 40-60 Hz, 35.5 VA
Electrical connections Via Ex e connection box 3 x cable gland
cable diameter : 7 mm–13 mm (M20), 14 mm–18 mm (M25)
terminals 0.5 to 2.5 mm
2
, Tightening torque 0.6 Nm
(power, signals, range position and remote choice, status signal)
Measuring ranges
Be sure to observe chapter 5
Selectable for 0-1, 0-3, 0-10, 0-30 and 0-100 vol% O
2
linear
choice via turning selection switch at PMA 50 EX or remote switching
External range indication Potential free contact for all measuring ranges.
Switching capacity 48 V DC, 200 mA DC,
Minimum contact rating 5 V/1 mA
Remote range selection Measuring ranges selectable via potential free contacts max. 30 V DC, 3 mA DC.
The function is displayed at the PMA 50 EX via LED.
Combined analog/digital indicator Analog meter with a scale of 0-30 and 0-100 % for each selected range
digital meter 4 ½ digit 9 mm high LCD-indicator for 0-100 % O
2
reading, selectivity
0.01 vol% O
2
Output signals 0/4-20 mA burden 270 Ω for every measuring range, electrically isolated; output
voltage max. 15 V (ex works).
Switchable max. burden 800 Ω, output voltage max. 30 V.
Output current limiting adjustable 20 mA to 22 mA
20.5 mA ex works
0-10 V DC, burden >100 KΩ for range 0-100 % isolated.
Response time for 90% FSD < 5 seconds at 60 Nl/h air
Accuracy after calibration 1 % of the span value of measuring range after calibration or 0.02 %O
2
depend-
ing on which value is the higher one
Reproducibility Analog output = < 1 % of measuring range / digital indication =
± 0.01 vol% O
2
Influence of ambient temperature No influence up to 50 °C [122 °F]
Influence of barometric pressure
The oxygen reading varies in direct proportion to changes of the barometric
pressure.
No influence from 0.6-1.5 bar abs. at PMA 50 EX/P/PD(-1-50) with process pres-
sure compensation
Influence of sample gas flow
Variation in gas flow between 0-60 Nl/h air will cause a difference of
< 0.2 vol.% O
2
Sample gas inlet pressure
Max. 1.1 bar abs.standard or in case of purging up to 1.5 bar abs.
(Minimum inlet pressure is required for necessary gas flow, PMA50 EX has no inte-
grated pump)
Sample gas outlet pressure Outlet of analyzer must discharge freely into atmosphere
or 0.6 to 1.5 bar abs. at version PMA 50 EX/P/PD(-1-50) with process pressure com-
pensation
Flow rate of sample gas Min. 10 Nl/h up to max. 60 Nl/h adjustable externally via flow meter (no flowmeter
inside)

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Temperature of sample gas -10 up to +50 °C [14 up to 122 °F] dry gas
O
2
-Transmitter temperature Fixed at +55 °C [131 °F] (factory-set)
Temperature cut-off At 72 °C [161.6 °F] via thermal fuse, non-reversible
Ambient temperature 0 to +50 °C [32 to 122 °F]
Storage temperature -20 to +60 °C [-4 to 140 °F] at relative air moisture of 0-90 % r.h.
Medium touched material Platinum, glass, PTFE, PVDF, stainless steel 316Ti, Epoxy
Connections measuring gas 1/4“ NPT female
Flow failure Thermo-conductive flow sensor downstream mounted after measuring cell
Status signal outlet
Change-over contact, switching capacity 250 V AC, 2A AC, 48 V DC, 200 mA
DC minimum contact rating 50 mW for temperature <+45 °C [113 °F]/> +60
°C [140 °F], defect light beam, measuring cell not coupled, flow failure
< 5 Nl/h, power supply error control, mains voltage breakdown, failure meas-
uring range selection
Classification/Protection II 2G Ex db eb IIC T4 Gb
IP54 EN 60529
Housing/color EX-d e wall mounted explosion-proof housing/white
Dimensions (H x W x D) 475 (535 mm with breathing and draining device) x 355 x 200 mm [≈ 18.7”
(535 mm [≈ 21.1”] with breathing and draining device) x 14” x 7.9”]
Weight Approx. 22 kg
[
≈ 48.5 lbs]
Certificate No. IBExU 16 ATEX 1192
IECEx IBE 16.0041
10.1 OPTIONS
Part
number
Options
05A9015 Zero suppression in range of 1 to 97 vol%; (Only in connection with Part No. 05A2500(a))
Externally switchable via potential free contacts, 30 V DC, 3 mA DC
(not with SIL-certification)
05A9005 Extra charge for one breathing and draining device for PMA50 EX enclosure, for sample gas pressures up
to max. 1.5 bar abs. and non-corrosive gases
05A9000 Purging the enclosure via two breathing and draining devices in the gas inlet and outlet, for sample gas
pressures up to max. 1.5 bar abs and/or corrosive gases, connection 1/4“ NPT female, purge gas inlet pres-
sure max. 1.1 bar abs., flow rate 10-60 Nl/h
90A0009 Measuring cell type PMC-1LB, solvent resistant.
90A0006 Measuring cell PMC-1G with glass solder. O-ring made of Chemraz
®
Please note: Nl/h and Nl/min refer to the German standard DIN 1343 and are based on these standard conditions: 0 °C [32 °F],
1013 mbar.
Chemraz
®
is a registered trademark for perfluoroelastomer by Greene Tweed, USA.

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11 DESCRIPTION
The main part of the PMA50 EX is the paramagnetic oxygen measuring cell.
This measuring principle is one of the most precise quantitative methods for determination of the oxygen
contents in the range of 0-100 vol% O2.
The Oxygen Analyzer PMA50 EX is destined for stationary operation. The mounting into an Ex db eb IIC T4
housing 1with breathing and draining devices in the sample gas inlet and outlet 2 , allows the analyzer to be
installed in an explosive atmosphere of equipment group II, category 2, and allows the analysis of explosive
gases of equipment group II, category 2.
The analyzer is thermostatted and regulated to a transmitter temperature of +55 °C [131 °F]. The temperature
controller is designed in such a way that the low voltage section and the 230 V power section are separated
via an opto-coupler with zero voltage switch.
The large heating elements mounted on the transmitter surface guarantee a fast and even temperature dis-
tribution.
The non-reversible overtemperature fuse prevents the transmitter from overheating above 72 °C [161.6 °F].
For better heat storage and insulation, the transmitter is equipped with an insulating cover.
Figure 1 shows the Oxygen Analyzer PMA50 EX in front view and side view.
1Enclosure 6Measuring range-LED 11 Cable gland M20
2Sample gas inlet, outlet 7Zero adjustment 12 Cable gland M25
3Breathing and draining devices
type MC95A
8Measuring range selector 13 Heating control-LED
4Equipotential bonding terminal 9Full scale adjustment 14 Status-LED collective status
5Measuring range: internal, exter-
nal-LED
10 Cable gland M20 15 Measured value display
Figure 1 PMA50 EX oxygen analyzer

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A window in the housing of the analyzer enables the control of the analog/digital measured value display 15,
the heating control LED 13 and status LED 14, as well as the measuring range LEDs 5and 6.
All operating elements are accessible from the outside and guarantee simple and user-friendly handling dur-
ing calibration as well as measuring range switching.
The operating elements are:
Full scale adjustment 9,
Measuring range selector 8and
Zero adjustment 7.
The oxygen display 15 of the PMA50 EX consists of a two-scale analog display instrument. Here the oxygen
value is displayed in a range of 0-100 vol% with a resolution of 0.1 vol%. A digital display is integrated in the
analog display. Here the oxygen value is displayed in a range of 0-100 vol% with a resolution of 0.1 vol%.
The measuring range can be switched via selector switch 8. The selected measuring range is indicated exter-
nally by a corresponding LED 6on the front panel of the PMA50 EX and by potential-free contacts (see Figure
6).
The measuring range can also be selected externally (see Figure 6). An external selection overrides the selec-
tor switch 8. LED 5on the front panel of the analyzer in conjunction with the corresponding measuring range
LED 6signals the external measuring range control.
The function of the analyzer heating is indicated by LED 13. When the LED flashes, the operating tem-
perature is reached.
The PMA50 EX has a collective status output as standard. This is a potential-free changeover contact
in'Safety-First' circuit. The switching capacity is 200 mA at 48 A DC or 2 A at 250 V AC. The status is indicated
by the status LED 14.
The following status messages are displayed:
Light source defective,
measuring cell not coupled,
flow failure < 5 Nl/h,
power supply error control,
mains voltage breakdown,
transmitter temperature < +45 °C [113 °F]/> +60 °C [140 °F],
failure measuring range selection.
11.1 PMA 50 EX/P/PD-1-50 WITH PRESSURE COMPENSATION AND ENCLOSURE PURGING
(WITHOUT SIL-CERTIFICATION)
In case of barometric or process -related pressure variations, the PMA 50 EX can be equipped with a special
pressure compensation. The pressure can be compensated in a range of 0.6 to 1.5 bar abs. This can eliminate
measurement errors due to pressure fluctuations.
In addition, the analyzer is equipped with an enclosure purging via breathing and draining devices in the
inlet and outlet. The enclosure purging is necessary in case of corrosive sample gas and / or pressure above
1.1 bar abs. In the event of a leak in the analyzer, no pressure can build up in the housing and the analyzer
cannot be damaged by corrosion if the sample gas is additionally corrosive. The required purge gas quantity
is 10 - 60 Nl/h according to the set sample gas quantity, and the purge gas inlet pressure is max. 1.1 bar abs.

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The enclosure purging has to flow off atmospherically free!
11.2 PMA 50 EX/P/PD WITH PRESSURE COMPENSATION (WITHOUT SIL-CERTIFICATION)
In case of barometric or process-related pressure variations, the PMA50 EX can be equipped with a special
pressure compensation. The pressure can be compensated in a range of 0.6 to 1.1 bar abs. This can eliminate
measurement errors due to pressure fluctuations.
11.3 OPTION ZERO SUPPRESSION (WITHOUT SIL-CERTIFICATION)
A zero suppression is possible for devices with pressure compensation within a range of 1 to 97 vol% O2in
increments of 1 %. The suppressed measuring range can, depending on the suppression, be located at the
position of one of the standard measuring ranges. The factory-set suppression can be switched on or off via
a switch at terminal points 22 or 23 in the connection box of the analyzer (see Figure 6). After switching off,
the original standard measuring range is active again.
11.4 OPTION ENCLOSURE PURGING OR ENCLOSURE VENTILATION
When measuring corrosive gases, it is recommended to equip the analyzer with the possibility of purging the
enclosure. This reduces the risk of the analyzer being destroyed by corrosion in the event of leaking gas paths.
Please select the option Art. No. 05A9000 ( 2 x breathing and draining devices). The required purge gas quan-
tity is 10 - 60 Nl/h according to the set sample gas quantity, and the purge gas inlet pressure is max. 1.1 bar
abs.
For increased inlet pressures from 1.1 bar to max. 1.5 bar abs. one breathing and draining device is also
required in accordance with the Ex certificate (see appendix). To do this, select the option with item no.
05A9005. For increased inlet pressure from 1.1 bar to max. 1.5 bar abs. and corrosive sample gas, the analyzer
needs to be equipped with the option Art.-No.: 05A9000.
The required purge gas quantity is 10 - 60 Nl/h according to the set sample gas quantity and the purge gas
inlet pressure is max. 1.1 bar abs.
For excess pressure operation (> 1.1 bar abs.) an enclosure ventilation according to the
ex-certificate is necessary. For additionally corrosive sample gas an enclosure purging is
necessary. Both have to flow off atmospherically free!
12 MEASURING PRINCIPLE
Oxygen is a gas with a significant paramagnetic susceptibility. The molecules of oxygen are attracted 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 oxygen. 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 dumb-
bell’s movement.

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2
4
3
1
GAS INLET
GAS OUTLET
7 8
5 6
9
1 Nitrogen-filled spheres 6 Photo cell
2Tightening strap out of platinum 7 Measuring amplifier
3Small mirror 8 Measuring amplifier
4Wedge-shaped pole pieces 9Display
5 Projektions-LED
Figure 2 Drawing of the measuring cell and optical signal processing
The measuring cell consists of two hollow spheres 1filled with nitrogen, which are formed into a dumbbell.
In the center of rotation of the dumbbell is a small mirror 3, which surrounds a wire loop, which is required
for the compensation procedure. The above system is fixed rotationally symmetrically in a glass tube with a
platinum strap 2and is screwed into two pole pieces 4.
Two permanent magnets generate an inhomogeneous magnetic field. When oxygen flows in, the oxygen
molecules are drawn into the magnetic field. The field lines on the wedge-shaped pole pieces 4are com-
pressed and the nitrogen-filled diamagnetic hollow spheres are forced out of the magnetic field. This causes
the dumbbell to rotate. The rotation motion is detected by an optical system consisting of mirror 3, projection
LED 5 and photocell 6.
When the dumbbell is pushed out of the magnetic field, the voltage of the photocell changes immediately.
The measuring amplifiers 7and 8 generate a corresponding current which generates an electromagnetic
counter-torque via the wire loop on the dumbbell. The counter torque returns the dumbbell to its zero posi-
tion.
Each change in the oxygen concentration causes a linear proportional change in the compensation current
and can therefore be read directly as oxygen value in % O2on the display 9.
Due to its very small stagnant volume (2 cm3) and the direct flow to the M&C measuring cell, an extremely
fast response time (T90-time) of one second for a high gas flow can be realized.

www.mc-techgroup.com PMA 50 EX | 1.01.04 17
13 GAS FLOW DIAGRAM
Figure 3 shows the gas flow diagram of the Oxygen Analyzer PMA50 EX.
1 : External fine filter
2 : External flow meter
3 : breathing and draining device
4 : Measuring cell
5 : Flow alarm sensor
6 : breathing and draining device
3 4 5 6
2 1
Figure 3 Gas flow diagram
The measuring cell 4must absolutely be protected against dust particles. Therefore, the upstream external
gas conditioning system should be equipped with a fine filter 1of at least 2 μm filter porosity (eg. type FP-
2T).
The maximum gas flow of 60 Nl/h can adjusted by an externally mounted flow meter 2 with a needle valve.
The sample gas enters the measuring cell 4via the inlet breathing and draining device 3.
A flow sensor 5in the outlet of the measuring cell is controlling the gas flow through the cell according to
the measuring principle of thermal conductivity. If the minimum gas flow is not reached, an alarm is auto-
matically triggered and is available as a status message at the collective status output. The status is also indi-
cated by a color change of LED 14 (see Figure 1) on the front panel of the analyzer (red/green).

18 PMA 50 EX | 1.01.04 www.mc-techgroup.com
Figure 4 shows the structure of the conditioning system according to the above-mentioned specification.
1 4
5 9
2
3
8
10
7
6
1
2
5
3
10
Sample
gas outlet
Sam
p
le
g
as
Condensate
I Atmospheric pressure
II Overpressure
Max 1.1 bar abs.
Max 1.1 bar abs.
8
1 Gascooler 7 Pressuredisplay
2 Finefilter 8 Overflowvalve
3 Flow meter 6-60 Nl/h 9 Condensate pump
4 Samplegaspump 10 Analyzer PMA50 EX
5 Filter 11 Condensate removal
6 Pressure reduction
Sample
gas outlet
11
Figure 4 Gas conditioning

www.mc-techgroup.com PMA 50 EX | 1.01.04 19
14 RECEIPT OF GOODS
The analyzer PMA50 EX is a completely pre-installed unit.
Please take the analyzer and possible special accessories carefully out of the packaging material immedi-
ately 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 analyzer PMA50 EX must be stored in a weather-protected and frost-
free area!
15 INSTALLATION
The PMA50 EX analyzer is designed for stationary wall mounting. All electrical connecting options are located
inside the connection box below the analyzer housing.
Figure 5 Dimensions for installation
The correct installation, as well as an optimized upstream sample gas treatment guarantee a long function-
ality and a minimum of maintenance.

20 PMA 50 EX | 1.01.04 www.mc-techgroup.com
When using the analyzer outdoors, it must be protected against the effects of the weather.
If possible, the installation should be done in constant climatic ambient conditions.
A vibration-free location is ideal for installation. If this is not possible, antivibration mounts must be used to
decouple the housing.
The analyzer must not be installed in direct proximity of heat sources.
Warning
The sample gas must be dry (dew point 5 °C [41 °F]), free from dust and the sample
gas temperature must not exceed 50 °C [122 °F]. Otherwise an upstream sample
gas cooler with automatic condensate removal is necessary.
A preceding fine filter of at least 2 μm is absolutely necessary.
The sample gas has to flow off atmospherically freely at the sample gas outlet,
because a pressure rise at the sample gas outlet and therefore in the measur-
ing cell falsifies the oxygen measurement.
The maximum inlet pressure is 1.1 bar abs. For the standard device and 1.5 bar
abs. for devices with enclosure purging or enclosure ventilation.
The analyzer is suitable for use in explosive atmosphere group II category 2.
Equipment with protection II 2G Ex db eb IIC T4 Gb (see type plate) is suitable
to measure explosive gases of group II category 2.
The oxygen analyzer PMA50 EX is suitable for analyzing gas mixtures classified in
Zone 1 with an oxygen content of up to 21 % by volume.
Higher oxygen concentrations are not covered by the ATEX directive.
16 SUPPLY CONNECTIONS
16.1 SAMPLE GAS INLET AND SAMPLE GAS OUTLET
The sample gas inlet and outlet are placed on the lower side of the analyzer. Both are equipped with breath-
ing and draining devices type MC95A. The breathing and draining devices have a 1/4“ NPT female thread.
Warning
The Ex-approval of the oxygen analyzer is only valid in connection with the ap-
proved breathing and draining devices. For this reason, it is not allowed to remove
them or to use other types of breathing and draining devices!