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MF420 O ZR 200x200
  • O2



The oxygen sensor MF420-O-Zr measures the oxygen concentration directly in the gas mixture and thus the oxygen partial pressure (absolute oxygen content). The measurement method is based on a dynamic process in two zirconium dioxide slices, which form a hermetically sealed chamber. The entire measuring range is linear.

Since the sensor monitors its function during operation and indicates malfunction of the hardware and the sensor element; moreover it is equipped with a function for diagnosis. A second oxygen sensor is not required.

The sensor can be calibrated without reference gas in atmospheric air. The output of the measurement values takes place via an analog (4 - 20 mA or 0 - 10 V) and a digital channel, the latter also transmits the error messages.


Measuring ranges and product specifications

The oxygen sensors of the product family MF420-O-Zr are available for a measuring range of 0.1 to 25 Vol.-% oxygen. Alternatively the sensor is available with an analog interface with 4-20 mA or 0-10 V and additionally has an independent digital output; via the digital channel a downstream logic for the self diagnostic operation can be realized.

Diagnostic function

The measurement signal output is given from two independent channels. The output signal of the analogue channel is linear between 4 and 20 mA (alternatively 0.1 to 10 V). The digital channel carries a pulse-width modulated alternating signal (high phase 5V, low-phase 0V). The length of the low-phase is the benchmark for the oxygen concentration to be computed in the downstream unit. The times are linear and system specific. The monitoring of both channels allows a fail-safe operation without a second sensor.

Functional Test

The probe is designed so that it can check the operation during its proper functioning. For this the test pin is applied to +24 V DC. The test simulates to the probe a 20% lower oxygen concentration. This change must reflect equally in the analog channel.


The oxygen measuring device MF420-O-Zr complies with the generic standards DIN EN 50270:2015 type1 and type2 and so with the EMC-directives 2014/30/EU.

Maintenance and Service

The device is delivered already calibrated. The interval of the maintenance meets the safety requirements. However, we recommend at least a six-monthly monitoring and a five-year replacement cycle. The device can be calibrated on fresh air and is supporting electrical as well as manual calibration. For the electrical calibration the test pin is set to +24 VDC. The probe calibrates autonomously on fresh air, within a tolerance range of 10%. Outside the tolerance range of the sensor it can be calibrated manually. Manual calibration is performed by means of a potentiometer inside the housing.

Product NameProduct FeaturesProduct Code
MF420-O-Zr Temperature range -20°C to +60°C
Measuring range: 0.1 - 25 Vol.-%
Output: 4 - 20 mA
MF420-O-Zr Temperature range -20°C to +60°C
Measuring range: 0.1 - 25 Vol.-%
Output: 0 - 10 V

Measuring principle Oxygen partial  
Power supply screw terminal 5 pin Conductor cross-section (rigid and flexible) 0,5mm² up to 2,5mm²
Voltage / tolerance 24 VDC ± 20%
Power consumption ca. 11,5 W
Connections Screw terminal 1 +24 VDC
Screw Terminal 2 0 V
Screw terminal 3 K2 digital I/O
Impuls and error,
electrical calibration
Screw terminal 4 K1 analogue output
linear 0 - 10 V or 4 - 20 mA
Screw terminal 5 Test
Test point K1 TP1 Indirect measurement of output
current more than 10 Ω (±0,2%)
Cable routing For Ø 4-10 mm
Measuring range 0,1 - 25 Vol.-% oxygen at 1013,25 hPa
1 - 253,31 hPa (O2)
Gas entrance Per Diffusion
Warm up time 5 min
Accuracy ±2% MBE at 25°C and 1013,25 hPa
Ambient temperature -20°C to +60°C Mind solar radiation!
Permissable humidity 0 to 95% relative humidity non condensing
Air pressure 800 hPa to 1100 hPa
Output 4-20 mA, max. burden 500 Ω or 0-10 V, impedance 1000 Ω
Housing Material Aluminium, red
Protection class IP 54
Weight ca. 600 g
Dimensions ca. L90 x W85 x H65 mm
without probe and PG screw connection
Probe protection tube Length ca. 75 mm
Diameter ca. 30 mm
Material Stainless steel

Pin Assignment:

Anschluss MF420 O ZR EN

Probe protection bar G2C1-Z13QV-A100-E04
Calibration adapter T0A0-A0003



Service case EF 0-1 l/min   T0X0-B1000-O01
Service case FF 0,5 l/min   T0X0-B1000-O04
Gas Nitrogen 99,999Vol.-% N2 34 l Z0A0-L2179
58 l Z0A0-M2179
110 l Z0A0-N2179
Gas Oxygen 34 l Z0A0-L1371
58 l Z0A0-M1371
110 l Z0A0-N1371

Gas synthetic air
Oxygen 20,9Vol.-% O2 in N2

34 l Z0A0-L1373
58 l Z0A0-M1373
110 l Z0A0-N1373
Gas Oxygen 23,5Vol.-% O2 in N2 34 l Z0A0-L1387
58 l Z0A0-M1387
110 l Z0A0-N1387

Other oxygen concentrations are available on request.