FIGARO
PRODUCT INFORMATION
TGS 821 -
Special Sensor for Hydrogen Gas
Features:
* High sensitivity and selectivity to hydrogen
gas
* Good repeatability in measurement and
excellent stability
* Uses simple electrical circuit
* Ceramic base resistant to severe
environment
Applications:
* Hydrogen gas detection for:
- transformer maintenance
- batteries
- steel industry usage
- etc.
The sensing element of Figaro gas sensors is a tin dioxide (SnO
2
) 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 821
has high sensitivity and selectivity to hydrogen gas. The sensor
can detect concentrations as low as 50ppm, making it ideal for a variety of
industrial applications.
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 resistance ratio (Rs/Ro) which is
defined as follows:
Rs = Sensor resistance of displayed gases at
various concentrations
Ro = Sensor resistance at 100ppm of hydrogen
Sensitivity Characteristics:
100
Air
Methane
Ethanol
10
Carbon monoxide
Rs/Ro
2
The figure below represents typical temperature and
humidity dependency characteristics. Again, the Y-axis is
indicated as sensor resistance ratio (Rs/Ro), defined as
follows:
Rs = Sensor resistance at 100ppm of hydrogen
at various temperatures/humidities
Ro = Sensor resistance at 100ppm of hydrogen
at 20擄C and 65% R.H.
Temperature/Humidity Dependency:
3
1
Rs/Ro
1
0.9
0.8
0.7
0.6
0.1
Hydrogen
R.H.
35%
65%
95%
0.01
10
100
1000
Concentration (ppm)
10000
0.5
-20
-10
0
10
20
30
Ambient Temperature (擄C)
40
50
IMPORTANT NOTE:
OPERATING CONDITIONS IN WHICH FIGARO SENSORS ARE USED WILL VARY WITH EACH CUSTOMER鈥橲 SPECIFIC APPLICATIONS. FIGARO STRONGLY
RECOMMENDS CONSULTING OUR TECHNICAL STAFF BEFORE DEPLOYING FIGARO SENSORS IN YOUR APPLICATION AND, IN PARTICULAR, WHEN CUSTOMER鈥橲 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.
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