% level oxygen measurement in a hazardous area


ATEX Zone 1
SIL rated
small footprint

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Oxygen measurement in a hazardous area.

The PMA50EEX provides fast, accurate and reliable oxygen measurement in a compact wall mounting system.

Paramagnetism is significantly higher for oxygen than other common gases.  The M&C magneto-dynamic measurement cell uses this physical phenomenon to provide the most accurate and reliable measurements available.

The small (2 ml) flow cell houses a robust sensor that can have a flow rate of up to 1 l/min. The small cell design improves speed of response and the paramagnetic sensor measures oxygen concentrations with a response time of less than 5 seconds.

The analyser is able to have 5 selectable ranges:

  • 0 to 1%
  • 0 to 3%
  • 0 to 10%
  • 0 to 30%
  • and 0 to 100%

This allows this system to be used for trace level oxygen measurements as well as oxygen purity applications.





Wall mounted

Measuring range

Selectable for 0 to 1, 0 to 3, 0 to 10, 0 to 30, and 0 to 100 vol% O2, linear and position external.

External range indication

Externally: potential free contact for all measuring ranges. Capacity 48 VDC 200 mA DC, minimum contact rating 5 V / 1 mA; internally: LED indication

Remote range control

Measuring range selectable via external potential free contacts 30 VDC 3 mA DC

Response time for 90 % FSD

< 5 seconds at 60 Nl/hr air

Accuracy after calibration

Deviation: analogue = ±1 % of span at range 3 to 100 % /

digital = ±0.1 vol.% O2: = ±2 % of span at range 1%


Deviation: analogue = <1 % of span /

digital = ±0.1 vol.% O2

Influence of ambient temperature

No influence up to 50 °C

Influence of barometric pressure

The oxygen reading varies in direct proportion to changes of the barometric pressure. no influence from 0.5 to 1.5 bar abs. at PMA 50 EEX/P/PD 1 to 50 with process pressure compensation

Influence of sample gas flow

Variation of gas flow between 0 to 60 Nl/hr air will cause a difference of < 0.2 vol.% O2

Sample gas inlet pressure

0.01 up to 1 bar g, or in case of purging up to 0.5 bar g (PMA 50 EEX required admission pressure for competent flow rate, no pump inside)

Sample gas outlet pressure

Outlet of analyser must discharge freely into atmosphere. or 0.6 to 1.5 bar abs. at version PMA 50 EEX/P/PD 1 to 50 with process pressure compensation

Flow rate of sample gas

max. 60 Nl/hr air (no flow meter inside)

Temperature of sample gas

-10 to +50 °C, dry gas

O2 transducer temperature

Fixed at 55 °C

Ambient temperature

-10 to +50 °C

Storage temperature

-20 to +60 °C, relative humidity 0 to 90 %rh



CE marked

IP protection

IP 54 EN 60529


EX II2G EEX d e IICT5 of EX II1/2G EEX d e [ia] IIC T5. KEMA 03 ATEX 2215X


Shipping weight

22 Kg



475 (535) H x 275 (355) W x 200 D mm


Explosion-proof wall mounted housing, blue

Wetted materials

Platinum, Glass, 316Ti Stainless Steel, Epoxy resin, PTFE, PVDF



Internal power unit 230 VAC standard, 115 VAC available ±10 %, 40 to 60 Hz. 8 VA option: rechargeable battery, recharged by the internal power unit. 10 hr battery capacity, 14 hr recharge time with instrument off.


Terminals 2.5 mm2, 3x PG cable glands (mains supply, signals, range identification, remote ranging, status alarm)

Sample gas connection

¼ " NPTi

Flow alarm

Thermo-conductive flow sensor downstream mounted after measuring cell

Status alarm

Change-over contact, switching capacity 250 VAC 2A AC, 48 VDC 200 mA DC minimum contact rating 50 mW for temperature < +45 °C / > +60 °C, defect light beam, measuring cell not coupled, flow alarm < 10 / > 70 Nl/h, power supply error control, mains voltage breakdown


Output signal

0 to 1 VDC, burden > 100 KΩ, for range 0 to 100 % isolated.

0/4 to 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)

Analogue/Digital indication

Analogue: selectable for each range with a scale of 0 to 30 and 0 to 100%. Digital: 3 ½ digit 9 mm high LCD for 0 to 100 % O2 reading, selectivity 0.1 vol.% O2

All specifications subject to change