The SB-12A is a tin diox semiconductor gas sensor which has an excellent performance in methane detection with significant low power consumption concept (120 mW). High sensitivity, low sensitivity to noise gases, quick response speed and strong poisoning resistance features achievereliable gas detection system

Structure

Gas sensitive semiconductor material is electrode wire are embedded in the element. The sensing element is installed in the metal housing which uses double stainless steel mesh (100 mesh) in the path of gas flow. This sensor unit is placed in an external housing which contains active charcoal

filter (Fig 1).

Operating conditions

Fig 2 shows the standard operating circuit for this model. The change of the sensor resistance (RS) is obtained as

the change of the output voltage across the fixed or variable resistor (RL).

In order to obtain the best performance and specified characteristics, the values of the heater voltage (VH) circuit voltage (VC) and load resistance (RL) must be within the range of values given in the standard operating conditions shown in the Specification table on the next page. 10 1 100 1000 10000 Gas concentration (ppm) RS / RS (at methane 1000 ppm) 0.2 air level methane CO hydrogen ethanol Sensitivity characteristics

Fig 3 shows the sensitivity characteristics curves of the SB- 12A (typical data). Sensitivity characteristics of the FIS gas sensors are expressed by the relationship between the sensor resistance and gas concentration. The sensor resistance decreases with an increase of gas concentration based on a logarithmic function. The sensitivity characteristics of the SB-12A is specified by the following parameters.

• Sensor resistance at methane 3000 ppm

• Sensor resistance change ratio: between methane 1000 ppm and 3000 ppm (slope)

• Sensor resistance change ratio: between methane 3000 ppm and ethanol 1000 ppm.  The SB-12A is a tin dioxide semiconductor gas sensor which has an excellent performance in methane detection with significant low power consumption concept (120 mW). High sensitivity, low sensitivity to noise gases, quick response speed and strong poisoning resistance features achieve reliable gas detection system applications.

Structure

Gas sensitive semiconductor material is a mini bead type and a heater coil and electrode wire are embedded in the element.