Oxygen Analyser

OPM 5000 Oxygen Analyser - Orthodyne

Oxygen Analyser (%) - OPM 5000

Paramagnetic analyser | Analysis of O2 in % level


The OPM 5000 Oxygen Analyser (%) manufactured by Orthodyne meets the requirements of industrial gas production. It includes the Paramagnetic sensor technology.


Oxygen is one of few gases showing significant paramagnetic properties which can be used for its measurement using the following method.

A small glass dumbbell filled with nitrogen is placed in an inhomogeneous magnetic field within the measuring cell. The system’s position of rest is defined by a light beam, a mirror on the dumbbell and a photo detector. The dumbbell is diamagnetic and tends to turn away from the magnetic field. The paramagnetic oxygen molecules of the sample gas, however, are drawn into the magnetic field, either displacing the dumbbell or forcing it to turn in the opposite direction. The turning is stopper by an opposite magnetic field generated by means of a coil around the dumbbell, the signal of the photo detector (deviation of the dumbbell from its position at rest) determining the necessary current intensity. The difference between the current when pure nitrogen is flowing and the current when sample gas is flowing across the measuring cell is proportionate to the concentration of oxygen in the sample gas.

The paramagnetic measurement is not dependent on inlet pressure as long as pressure is in working range. However, the measurement is dependent on the outlet pressure. Compensation measures are necessary, in particular for measurements above concentrations normally found in the air of a room (back pressure regulator, pressure measurements at the outlet with calculated compensation, etc.).

The OPM5000 measuring cell has a small measuring volume of approx. 3cm¬ and it is heated and regulated at a fixed temperature of 55°C.

Cross Interference

The selectivity of the measuring system is based on the extraordinarily high susceptibility of oxygen. The susceptibilities of other gases are relatively so low that the presence of foreign gases can be ignored in most cases. Significant measuring errors occur where the sensor has been calibrated with nitrogen as reference gas, but the sample gas consists mainly of other gases with considerable magnetic susceptibility. The Oxygen sensor shows a measured value even if the sample gas contains no oxygen, i.e. it displays a cross-sensitivity to another gas. Such gases often occur as process gases but are not available as test gases for calibration, especially not as a mixture.

Some Global References

Company Type of analyser Model Measurements
Air Liquide (USA) Air OPM O2 (%)
Air Products (Spain) / OPM O2 (%) ASSAY

Type of configurations

Model# paramagnetic sensor
OPM 50011
OPM 50022
OPM 50033*
OPM 50044*

*OPM 5003 and OPM 5004 will be assembled inside a rack of 365mm depth and 6U height.and 6U height.

Technical specifications

Measuring range0 – 100 % O2
Power supply115 – 230 VAC
Measurement signal0 – 1 V
Response time T90
with gas fl ow 150 ml/min.
< 3 s
Max. gas flow for direct gas supply100 ml/min. typical
Gas flow (pressure compensated)240 ml / min.
(100 ml/min. for the cell and 140 ml/min. by pass)
Gas flow (flow compensated)100 ml / min.
Ambient temperature0 – 45 °C
Storage temperature0 – 45 °C
Relative humidity90% without condensation
Heating temperature55°C
Warm-up (stability) time< 1h / 24h
Temperature sensorIncorporated for the heating
Safety temperature sensorIncorporated for 80°C
Linearity< ± 0.1 % O2
Zero point drift< ± 0.1 % O2 a week
Repeatability< ± 0.02 % O2
Temperature effects (zero point)< ± 0.03 % O2 /°C
Temperature effects (sensitivity)< ± 0.1 % of measured value/°C


OPM 5000 Oxygen Analyser Dimensions


> Air separation plants.

> Specialty gas laboratories.

> Process control.

> Steel industry.

> Cryogenic truck loading station.

> Basic research.

> Materials research.

> Monitoring of atmospheres.

Discover which analyser(s) you need for your analytical requests. Check the application here !


Excellent response time
Keyboard for intuitive operation
Extremely high linearity
From 0 to 100% O2 in a single range
Reliability and reproducibility
Built-in bypass

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OPM 5000 Oxygen Analyser Brochure
OPM 5000