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Carbon Monoxide + Hydrogen Sulfide Sensor (CO + H2S Sensor) - COH-A2

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• Range: 1,000 ppm CO limit of performance warranty
• Range: 200 ppm H2S limit of performance warranty
• Sensitivity: 50 to 100 nA/ppm in 400ppm CO
• Sensitivity: 600 to 950 nA/ppm in 20ppm H2S
• Temperature range: -30 to 50°C
• Pressure range: 80 to 120 kPa
• Humidity range: 15 to 90 %rh continuous
• Weight: < 6 g

Model Number: COH-A2
Data Sheet:

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Product Specification

COH-A2 Carbon Monoxide + Hydrogen Sulfide Sensor Introduction
Personal gas safety monitors can be found in almost every industry, with the requirement for multiple gas detection becoming commonplace. Most of these gas detectors measure both Carbon Monoxide and Hydrogen Sulfide.

Alphasense new 2sense H2S+CO gas sensor allows designers to reduce significantly their gas detector size and cost. The patented 2sense uses a new approach to dual gas sensor design.

A larger version of the D2 sensor, which has a proven track record in the field over many years, the 2sense does not compromise performance or long term stability over the standard two-sensor solution when measuring both H2S and CO.

2Sense Dual Gas
Save space and save cost with our 2Sense family of dual gas sensors, in the A-series 20mm size.
With a patented design and best response, these dual sensors offer the required performance with obvious advantages.

CO / H2S the COH-A2 builds on 10 years of experience with our original D2 sensor.

Carbon Monoxide Sensor (CO Sensor) Specification

Carbon Monoxide Sensor (CO Sensor) PERFORMANCE
Sensitivity	nA/ppm in 400ppm CO	50 to 100
Response time	t90 (s) from zero to 400ppm CO	< 35
Zero current	ppm equivalent in zero air	-3 to +3.5
Resolution	rms noise (ppm equivalent)	< 0.5
Range	ppm CO limit of performance warranty	1,000
Linearity	ppm error at full scale, linear at zero and 400 ppm CO	10 to 40
Overgas limit	maximum CO for stable response to gas pulse	5,000

Carbon Monoxide Sensor (CO Sensor) LIFETIME
Zero drift	ppm equivalent change/year in lab air	< 0.5
Sensitivity drift	% change/year in lab air, monthly test	< 4
Operating life	months until 80% original signal (24 month warranted)	24

Carbon Monoxide Sensor ENVIRONMENTAL
Sensitivity @ -20°C	% (output @ -20°C/output @ 20°C) @ 100ppm CO	35 to 45
Sensitivity @ 50°C	% (output @ 50°C/output @ 20°C) @ 100ppm CO	120 to 140
Zero @ -20°C	ppm equivalent change from 20°C	0 to 5
Zero @ 50°C	ppm equivalent change from 20°C	0 to -20

Carbon Monoxide Sensor (CO Sensor) CROSS SENSITIVITY
Filter Capacity	ppm-hours of Hydrogen Sulfide	nd
H2S sensitivity	% measured gas @ 20ppm H2S	< 10
H2 sensitivity	% measured gas @ 400ppm H2 @ 20°C	< 8
NO2 sensitivity	% measured gas @ 10ppm NO2	< 3
Cl2 sensitivity	% measured gas @ 10ppm Cl2	< 0.1
NO sensitivity	% measured gas @ 50ppm NO	< 50
SO2 sensitivity	% measured gas @ 20ppm SO2	< 1
C2H4 sensitivity	% measured gas @ 400ppm C2H4	< 60
NH3 sensitivity	% measured gas @ 20ppm NH3	< 0.1

Carbon Monoxide Sensor (CO Sensor) KEY SPECIFICATIONS
Temperature range	°C	-30 to 50
Pressure range	kPa	80 to 120
Humidity range	%rh continuous (see note below)	15 to 90
Storage period	months @ 3 to 20°C (stored in sealed pot)	6
Load resistor	Ω (recommended)	10 to 47
Weight	g	< 6

Hydrogen Sulfide Sensor (H2S Sensor) Specification

Hydrogen Sulfide Sensor (H2S Sensor) PERFORMANCE
Sensitivity	nA/ppm in 20ppm H2S	600 to 950
Response time	t90 (s) from zero to 20ppm H2S @ 20°C	< 30
Zero current	ppm equivalent in zero air	0 to -0.3
Resolution	rms noise (ppm equivalent)	< 0.05
Range	ppm H2S limit of performance warranty	200
Linearity	ppm error at full scale, linear at zero and 20ppm H2S	0 to -3
Overgas limit	maximum ppm H2S for stable response to gas pulse	400

Hydrogen Sulfide Sensor (H2S Sensor) LIFETIME
Zero drift	ppm equivalent change/year in lab air	< 0.1
Sensitivity drift	% change/year in lab air, monthly test	< 2
Operating life	months until 80% original signal (24 month warranted)	24

Hydrogen Sulfide Sensor (H2S Sensor) ENVIRONMENTAL
Sensitivity @ -20°C	% (output @ -20°C/output @ 20°C) @ 20ppm H2S	80 to 90
Sensitivity @ 50°C	% (output @ 50°C/output @ 20°C) @ 20ppm H2S	105 to 115
Zero @ -20°C	ppm equivalent change from 20°C	< ±0.05
Zero @ 50°C	ppm equivalent change from 20°C	< 0 to 0.2

Hydrogen Sulfide Sensor (H2S Sensor) CROSS SENSITIVITY
NO2 sensitivity	% measured gas @ 10ppm NO2	< -25
Cl2 sensitivity	% measured gas @ 10ppm Cl2	< -12
NO sensitivity	% measured gas @ 50ppm NO	< 30
SO2 sensitivity	% measured gas @ 20ppm SO2	< 11
CO sensitivity	% measured gas @ 400ppm CO	< 7
H2 sensitivity	% measured gas @ 400ppm H2	< 0.2
C2H4 sensitivity	% measured gas @ 400ppm C2H4	< 0.5
NH3 sensitivity	% measured gas @ 20ppm NH3	< 0.1