Gas Detectors and control
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Sensor&Module |
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Gas Sensor
-Semiconductor type
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Oxide semiconductors such as
SnO2, ZnO, In2O3, and TiO2 show the large
changes in resistance at the exposure to
reducing(CO, H2, CH4, C2H6) or oxidiging
gases(NO, NO2) at 300-4000oC. This is called as
'semiconductor-type' gas sensors. The gas
sensing mechanim is being explained by the
reaction of reducing (or oxidizing) gases with
surface oxygen. The followings are sensing
mechanism of SnO2. SnO2 is n-type semiconductor
with
oxygen deficiency. The lattice oxygen is
evaporated in the form of gas, which makesthe
doubly ionized oxygen vacancy and electrons.
This electrons play the role in conduction. If
tin dioxide is heated at 300-400oC, the oxygen
in the atmosphere are adsorbed at the surface of
SnO2 with the negative charge. Because electron
is provided from the surface of crystal, the
surface of tin oxide becomes electron depletion
layer. This means the formation of potential
barrier near the grain boundary. The core with
yellow tone shows the conducting phase and the
red tone of surface layer indicates the
resistive shell layer.If CO is present in the
atmosphere, the CO oxidizes into CO2 with the
reaction of adsorbed oxygen and remaining
electron returns to the SnO2 crystal. This
increases the electrical conductivity to a great
extent. So, we can detect CO by the remarkable
resistance decrease. The similar mechanism can
be applied to the
detection of other reducing gases. Electrochemically speaking, the reduction in
resistance occurs mainly at the surface and can
be explained by the reduction of potential
barrier. |
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Fig. The CO sensing mechanism of
semiconductor-type gas sensor. |
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Carbon Monoxide (CO)
Sensor(TK-202)
Carbon Monoxide sensor for use in industrial or
mining applications. This unit offers excellent
long life performance with stable sensing
characteristics.
Features
• High Sensitivity
• Detection Range: 10 - 1,000 ppm CO
• Response Time: <150s
• Heater Voltage: 5.0V
• Dimensions: 16mm Diameter, 10mm High excluding
pins, Pins - 6mm High
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LPG Sensor(TK-203)
Ideal sensor for use to detect the presence of a
dangerous LPG leak in your car or in a service
station, storage tank environment. This unit can
be easily incorporated into an alarm unit, to
sound an alarm or give a visual indication of
the LPG concentration. The sensor has excellent
sensitivity combined with a quick repsonse time.
The sensor can also sense iso-butane, propane,
LNG and cigarette smoke.
Features
• High Sensitivity
• Detection Range: 100 - 10,000 ppm iso-butane
propane
• Fast Response Time: <10s
• Heater Voltage: 5.0V
• Dimensions: 18mm Diameter, 17mm High excluding
pins, Pins - 6mm High
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Alcohol Sensor(TK-210)
Alcohol Sensor for use in Breathalyser's or in
an alarm unit, to detect the presence of alcohol
vapours. This sensor unit offers very high
sensitivity, combined with a fast response time.
The unit will work with a simple drive circuit
and offers excellent stability with long life.
Features
• High Sensitivity
• Detection Range: 10 - 1,000 ppm Alcohol
• Fast Response Time: <10s
• Heater Voltage: 5.0V
• Dimensions: 16mm Diameter, 10mm High excluding
pins, Pins - 6mm High
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Carbon
Dioxide CO2 Sensor(TK-220)
Excellent performance CO2 Sensor, for use in a
wide range of applications, including air
quality monitoring, smoke alarms, mine and
tunnel warning systems, greenhouses, etc. The
sensor is easy to use and can be easily
incorporated in a small portable unit.
Features
• High Sensitivity
• Detection Range: 0 - 10,000 ppm CO2
• Response Time: <60s
• Heater Voltage: 6.0V
• Dimensions: 16mm Diameter, 15mm High excluding
pins, Pins - 6mm High
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LPG
Sensor(TK-260)
Ideal sensor for use to detect the
presence of a dangerous LPG leak in
your car or in a service station,
storage tank environment. This unit
can be easily incorporated into an
alarm unit, to sound an alarm or
give a visual indication of the LPG
concentration. The sensor has
excellent sensitivity combined with
a quick repsonse time. The sensor
can also sense iso-butane, propane,
LNG and cigarette smoke.
Features
• High Sensitivity
• Detection Range: 100 - 10,000 ppm
iso-butane propane
• Fast Response Time: <10s
• Heater Voltage: 5.0V
• Dimensions: 18mm Diameter, 17mm
High excluding pins, Pins - 6mm High
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