Ceramic base resistant to severe environments For hydrogen sulfide detectors - Figaro Engineering - #1

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The sensing element of Figaro gas sensors is a tin dioxide (SnCte) semiconductor which has low conductivity in clean air. In the presence of a detectable gas, the sensor's conductivity increases depending on the gas concentration in the air. A simple electrical circuit can convert the change in conductivity to an output signal which corresponds to the gas concentration.

The TGS 825 has high sensitivity to hydrogen sulfide. The sensor can detect concentrations of hydrogen sulfide as low as 5ppm, making it ideal for application in gas leak detection.

The figure below represents typical sensitivity char-acteristics, all data having been gathered at standard test conditions (see reverse side of this sheet). The Y-axis is indicated as sensor ressstance ratoo (Rs/Ro) which is defined as follows:

Rs = Sensor resistance of displayed gases at

various concentrations Ro = Sensor resistance at 50ppm of hydrogen sulfide at 20°C and 65% R.H.

The figure below represents typical temperature and humidity dependency characteristics. Again, the Y-axis is indicated as sensor ressstance ratoo (Rs/Ro), defined as follows:

Rs = Sensor resistance at 50ppm of hydrogen

sulfide at various temp./humidities Ro = Sensor resistance at 50ppm of hydrogen sulfide at 20°C and 65% R.H.

10

5

3

2

2

1

0.5

o

o:

o

1

0.8 0.6

0.4

0.1

-20

0 2040

Ambient Temperature (°C)

60

10 2050

Concentration (ppm)

100

important note: operating conditions in which figaro sensors are used will vary with each customer's specific applications. figaro strongly recommends consulting our technical staff before deploying figaro sensors in your application and, in particular, when customer's target gases are not listed herein. figaro cannot assume any responsibility for any use of its sensors in a product or application for which sensor has not been specifically tested by figaro.