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Comparison of the characteristics of small commercial NDIR CO2 sensor models and development of a portable CO2 measurement device.

Yasuda T, Yonemura S, Tani A - Sensors (Basel) (2012)

Bottom Line: When the correction was applied to the sensors, the accuracy of measurements improved significantly in the case of the K30 and AN100 units.In particular, in the case of K30 the relative RMS error decreased from 24% to 4%.This indicates that acceptable accuracy can be realized using the calibration method developed in this study.

View Article: PubMed Central - PubMed

Affiliation: Plant and Environmental Sciences, Department of Environmental Health Science, University of Shizuoka, Shizuoka Japan. p09402@u-shizuoka-ken.ac.jp

ABSTRACT
Many sensors have to be used simultaneously for multipoint carbon dioxide (CO(2)) observation. All the sensors should be calibrated in advance, but this is a time-consuming process. To seek a simplified calibration method, we used four commercial CO(2) sensor models and characterized their output tendencies against ambient temperature and length of use, in addition to offset characteristics. We used four samples of standard gas with different CO(2) concentrations (0, 407, 1,110, and 1,810 ppm). The outputs of K30 and AN100 models showed linear relationships with temperature and length of use. Calibration coefficients for sensor models were determined using the data from three individual sensors of the same model to minimize the relative RMS error. When the correction was applied to the sensors, the accuracy of measurements improved significantly in the case of the K30 and AN100 units. In particular, in the case of K30 the relative RMS error decreased from 24% to 4%. Hence, we have chosen K30 for developing a portable CO(2) measurement device (10 × 10 × 15 cm, 900 g). Data of CO(2) concentration, measurement time and location, temperature, humidity, and atmospheric pressure can be recorded onto a Secure Digital (SD) memory card. The CO(2) concentration in a high-school lecture room was monitored with this device. The CO(2) data, when corrected for simultaneously measured temperature, water vapor partial pressure, and atmospheric pressure, showed a good agreement with the data measured by a highly accurate CO(2) analyzer, LI-6262. This indicates that acceptable accuracy can be realized using the calibration method developed in this study.

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Time course of the output of S100 sensor model. Solid line shows actual sensor output value. Dotted line shows CO2 concentration estimated using α and τ.
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f7-sensors-12-03641: Time course of the output of S100 sensor model. Solid line shows actual sensor output value. Dotted line shows CO2 concentration estimated using α and τ.

Mentions: It is necessary to consider the response delay of the sensor output values against actual CO2 concentration change. Figure 7 shows the response of the output of the S100 sensor model. A time constant for the response to equilibrium α and an offset of time τ in response of each sensor model were calculated from Equation (7) (Table 3). Each sensor had a good agreement between the calculated curve fit and actual data when τ in response was employed. The 90% response time of all the sensors, excluding T6615, was <3 min, and these values were all larger than the catalog values. The responses of small CO2 sensors used in this study were slower than that of the reference sensor GMM222C. No clear relationship between the length of use and the sensor response was observed. No temperature dependency of α and τ was also confirmed (data are not shown).


Comparison of the characteristics of small commercial NDIR CO2 sensor models and development of a portable CO2 measurement device.

Yasuda T, Yonemura S, Tani A - Sensors (Basel) (2012)

Time course of the output of S100 sensor model. Solid line shows actual sensor output value. Dotted line shows CO2 concentration estimated using α and τ.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3376595&req=5

f7-sensors-12-03641: Time course of the output of S100 sensor model. Solid line shows actual sensor output value. Dotted line shows CO2 concentration estimated using α and τ.
Mentions: It is necessary to consider the response delay of the sensor output values against actual CO2 concentration change. Figure 7 shows the response of the output of the S100 sensor model. A time constant for the response to equilibrium α and an offset of time τ in response of each sensor model were calculated from Equation (7) (Table 3). Each sensor had a good agreement between the calculated curve fit and actual data when τ in response was employed. The 90% response time of all the sensors, excluding T6615, was <3 min, and these values were all larger than the catalog values. The responses of small CO2 sensors used in this study were slower than that of the reference sensor GMM222C. No clear relationship between the length of use and the sensor response was observed. No temperature dependency of α and τ was also confirmed (data are not shown).

Bottom Line: When the correction was applied to the sensors, the accuracy of measurements improved significantly in the case of the K30 and AN100 units.In particular, in the case of K30 the relative RMS error decreased from 24% to 4%.This indicates that acceptable accuracy can be realized using the calibration method developed in this study.

View Article: PubMed Central - PubMed

Affiliation: Plant and Environmental Sciences, Department of Environmental Health Science, University of Shizuoka, Shizuoka Japan. p09402@u-shizuoka-ken.ac.jp

ABSTRACT
Many sensors have to be used simultaneously for multipoint carbon dioxide (CO(2)) observation. All the sensors should be calibrated in advance, but this is a time-consuming process. To seek a simplified calibration method, we used four commercial CO(2) sensor models and characterized their output tendencies against ambient temperature and length of use, in addition to offset characteristics. We used four samples of standard gas with different CO(2) concentrations (0, 407, 1,110, and 1,810 ppm). The outputs of K30 and AN100 models showed linear relationships with temperature and length of use. Calibration coefficients for sensor models were determined using the data from three individual sensors of the same model to minimize the relative RMS error. When the correction was applied to the sensors, the accuracy of measurements improved significantly in the case of the K30 and AN100 units. In particular, in the case of K30 the relative RMS error decreased from 24% to 4%. Hence, we have chosen K30 for developing a portable CO(2) measurement device (10 × 10 × 15 cm, 900 g). Data of CO(2) concentration, measurement time and location, temperature, humidity, and atmospheric pressure can be recorded onto a Secure Digital (SD) memory card. The CO(2) concentration in a high-school lecture room was monitored with this device. The CO(2) data, when corrected for simultaneously measured temperature, water vapor partial pressure, and atmospheric pressure, showed a good agreement with the data measured by a highly accurate CO(2) analyzer, LI-6262. This indicates that acceptable accuracy can be realized using the calibration method developed in this study.

Show MeSH