Gas Sensor Carbon Monoxide

The ME1250 gas sensor is a remote measuring unit for monitoring the gas concentration of carbon monoxide. This toxic gas is mainly found in the exhaust of petrol engines. The sensor is used to control ventilation and to alert for evacuation.

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

Measuring Ranges

The carbon monoxide sensor can be equipped with two different measuring cells. The exhaust gas variant is suitable for ventilation controls. The more robust industrial variant offers a higher measuring range up to 1,000 ppm. Other measuring ranges on request.

Technical Specifications

Measurement method	Electrochemical
Measuring range	Exhaust gas measurement 0…300 ppm	Industrial gas measurement 0…1,000 ppm
Alarm thresholds	Alarm 1: 50 ppm Alarm 2: 200 ppm	Alarm 1: 50 ppm Alarm 2: 200 ppm
Lifespan in air	up to 3 years	according to cell manufacturer
Break-in period	12 h	according to cell manufacturer
Response time t90	< 40 sec
Operating voltage	10…28 VDC	nominal 24 VDC
Ambient temperature	-40…+50 °C
Humidity	15…90% rF	non-condensing
Mounting height	on the ceiling	lighter than air
Casing	ABS plastic Light gray RAL 7035 81 x 121 x 56 mm 250 g	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 codes
Exhaust gas: 300 ppm Industry: 1,000 ppm	12BUS-CO-32 12BUS-CO-13	1250-CO-32 1250-CO-13
Description	Gas Sensor ME 1250 CO Carbon Monoxide Bus communication	Gas Sensor ME 1250 CO Carbon Monoxide 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	Application	Lifespan
CELL-CO-M1000	Measuring cell CO 20 mm	Exhaust gas	up to 3 years
CELL-CO-CF1000	Measuring cell CO 32 mm	Industry	up to 3 years

Gas concentration

• Exposure above measuring range requires recalibration
• High gas concentration can destroy the measuring cell

Cross sensitivity

For the measuring cell CELL-CO-CF1000

Gas	Concentration	Reading
Ethene C2H4	1,000 ppm	< 250 ppm
Formaldehyde CH2O	5 ppm	0 ppm
Chlorine Gas Cl2	20 ppm	0 ppm
Hydrogen H2	400 ppm	< 200 ppm
Hydrogen Sulfide H2S	20 ppm	0 ppm
Hydrogen Chloride HCl	20 ppm	0 ppm
Nitric Oxide NO	50 ppm	0 ppm
Nitrogen Dioxide NO2	20 ppm	0 ppm
Sulfur Dioxide SO2	100 ppm	0 ppm

Health hazards

Carbon Monoxide	Symptoms
200 ppm	Slight headache, dizziness
400 ppm	Headache in the forehead region
800 ppm	Dizziness and nausea, convulsions within 45 minutes
1,600 ppm	Unconscious within 2 hours, possible death within 1 hour
3,200 ppm	Dizziness/nausea for 10 minutes, death within 30 minutes