GD-70D - 138 -
<Semiconductor Type>
Metal dioxide can measure gas concentration based on changes
in the electric conductivity of semiconductor caused by gas
accumulated on its surface.
RL: Load resistance Vo: Output voltage
VH: Heater voltage Vs: Sensor voltage
Special precautions for this principle
1. The detector is interfered by gases other than the gas to be detected, and vapors.
Please note that the alarm can be triggered by interference. In addition, the reading may be affected by
environmental (temperature, humidity, etc.) changes in the installation site.
2. The alarm must be set within a range where the performance of the detector can be ensured.
In facilities compliant with the High Pressure Gas Safety Act, an alarm setting below our standard
alarm setpoint may trigger a false alarm.
3. This is a safety device, not a control device.
The alarm contact output of the detector must be used for an external alarm lamp/buzzer, while the
alarm signal output must be used for an indicator or external recorder. If these outputs are used to
control other devices, we shall not be responsible for any malfunctions.
4. The gas sensing part of this detector is made of porous sintered bodies. If silicon or sulfide compounds
are accumulated on the surface of the porous sintered body, the area of the gas sensing part becomes
smaller, which may result in serious sensitivity deterioration.
For safety reasons, do not use the detector in the presence of silicon or sulfide compounds.
5. It is recommended that a regular maintenance and gas calibration are performed for every six months
in accordance with the regulations.
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