Teledyne M300E CARBON DIOXIDE SENSOR OPTION 67A, 5.9.1.CO2 SENSOR RANGES AND SPECIFICATIONS

Teledyne API – Technical Manual - Model 300E Family CO Analyzers Optional Hardware and Software

5.9.CARBON DIOXIDE SENSOR (OPTION 67A)

The optional CO2 sensor allows the M300E/EM to measure both CO and CO2 simultaneously. This option includes a CO2 sensor probe, a Logic PCA that conditions the probe output and issues a 0-5 VDC signal to the analyzer’s CPU that is used to compute the CO2 concentration.

The M300E/EM receives this input, scales it based on the values of the CO2_SLOPE and CO2_OFFSET recorded during calibration (see Section 9.7.2).

Figure 3-4 shows the location of the Sensor Probe and PCA within the M300E/EM.

The CO2 sensor assembly itself does not have any serviceable parts and is enclosed in an insulated canister.

5.9.1.CO2 SENSOR RANGES AND SPECIFICATIONS

Table 5-6: CO2 Sensor - Available Ranges

OPTION NO.		RANGES		ANALYZER MODEL(S)
67A		0-20%		M300EM
	Table 5-7: CO2 Sensor Specifications
		Accuracy at 25˚C	0.02% CO + 2% of reading
		Linearity	0.5 % of full scale
Typical Temperature Dependence			-0.1% FS / ˚C
	Long Term Stability		<+15 % FS / 2 years
		Response time	20 seconds
		Warm up time	5 minutes
	Power consumption		2.5 watts

5.9.2.THEORY OF OPERATION

5.9.2.1.NDIR measurement of CO2

The optional CO2 sensor is a silicon based Non-Dispersive Infrared (NDIR) sensor. It uses a single-beam, dual wavelength measurement method.

An infrared source at one end of the measurement chamber emits IR radiation into the sensor’s measurement chamber where light at the 4.7 μm wavelength is partially absorbed by any CO2 present. A special light filter called a Fabry-Perot Interferometer (FPI) is electronically tuned so that only light at the absorption wavelength of CO2 is allowed to pass and be detected by the sensor’s IR detector.

A reference measurement is made by electronically shifting the filter band pass wavelength so that no IR at the CO2 absorption wavelength is let through.

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