Gas Sensor Nitrogen Dioxide

The ME1250 Gas Sensor is a remote measuring unit for monitoring gas concentration of nitrogen dioxide. This toxic gas is mainly found in the exhaust gases of diesel engines. The sensor is mostly used to control ventilation and alarms for personal protection.

The microprocessor-controlled electronics of the sensor, adapted to the specific properties of the measuring cell, enable fast and reliable signal processing. The measured gas con-centration is transmitted to a Gas Control Panel, which can manage a large number of distributed gas sensors.

Thanks to bus communication, only one cable is required, which can be continued from sensor to sensor. The ME 1250 Gas Sensor is also available with an analogue output signal of 4…20 mA. The measured gas concentration can thereby be processed by other PLC (Programmable Logic Controllers).

The optional relay module expands the ME 1250 Gas Sensor internally with 3 relays for direct switching of signal transmitters without the use of a control panel.

Advantages

• Automatic zero point calibration
• Active noise reduction on the measurement signal
• Linear measurement signal depending on the gas concentration
• High response sensitivity with short response time
• Selective and reliable measurement with a stable measurement signal and zero point
• Temperature-compensated measurement signal
• Long service life

For the combined measurement of petrol and diesel exhaust gases we recommend our exhaust gas warning systems with the combination sensor CO/NO2.

Technical Specifications

Measurement method	Electrochemical
Measuring range	0…5 ppm	other measuring ranges on request
Alarm thresholds	Alarm 1: 0.8 ppm Alarm 2: 2.0 ppm	recommendation
Lifespan in air	up to 2 years	according to cell manufacturer
Break-in period	4 h	according to cell manufacturer
Response time t90	< 30 sec
Operating voltage	10…28 VDC	nominal 24 VDC
Ambient temperature	-40…+50 °C
Humidity	15…90% rF	non-condensing
Mounting height	30-150 cm above floor
Casing	Default: ABS plastic Light gray RAL 7035 81 x 121 x 56 mm 250 g	Optional: Powder-coated aluminum Orange RAL 2004 80 x 125 x 59 mm 500 g
Cable entry	M20
EU conformity	CE mark including EMC test

Versions

Article code	12BUS-NO2-50	1250-NO2-50
Description	Gas Sensor ME 1250 NO2 Nitrogen Dioxide Bus communication	Gas Sensor ME 1250 NO2 Nitrogen Dioxide Analogue
Output signal	Bus communication with gas control panel	Analogue 4…20 mA Load max. 800 Ω at 24V input
Connection	4-core cable U72M 1x4x0.6 mm Shielded	3-core cable U72M 1x4x0.6 mm or CY 0.5 mm2 Shielded
Topology	Bus, tree or star topology	Star topology
Power	< 0.15 W	< 0.8 W

Signal Processing

Accessories

Article Code	Description
1250-REL	Relay module for single sensor ME 1250
1250-AIR-BOX	Ventilation duct add-on box for gas sensor ME 1250
1250-AIR-FLOW	Fitting hose connection for gas sensor ME 1250
1250-SUP	Mounting plate round pillars for gas sensor ME 1250
1250-SCHUTZ	Sun and weather protection for gas sensor ME 1250

Consumables

Article code	Description	Lifespan
CELL-NO2-M5	Measuring cell for nitrogen dioxide Blue measuring cell 20 mm	up to 2 years
CELL-NO2-CA2	Measuring cell for nitrogen dioxide White measuring cell 32 mm	up to 2 years

Gas concentration

• Exposure above 5 ppm requires recalibration
• Exposure above 10 ppm can destroy the measuring cell

Cross sensitivity

For the measuring cell CELL-NO2-CA2

Gas	Concentration	Reading
Ethene C2H4	100 ppm	0 ppm
Formaldehyde CH2O	7 ppm	0 ppm
Chlorine Gas Cl2	20 ppm	15 ppm
Carbon Monoxide CO	100 ppm	0 ppm
Ethanol C2H5OH	60 ppm	0 ppm
Hydrogen H2	100 ppm	0 ppm
Hydrogen Sulfide H2S	20 ppm	< -0.1 ppm
Hydrogen Chloride HCl	20 ppm	0 ppm
Ammonia NH3	80 ppm	0 ppm
Nitric Oxide NO	1 ppm	0 ppm
Ozone O3	0.2 ppm	0 ppm
Sulfur Dioxide SO2	5 ppm	0 ppm