FIGARO
PRODUCT INFORMATION
0.1
1
10
10 100 1000
Rs/Ro
Concentration (ppm)
Air
Iso-butane
Hydrogen
Ammonia
Ethanol
Applications:
TGS 826 - for the Detection of Ammonia
* Ammonia leak detection in refrigerators
* Ventilation control for the agricultural and
poultry industries
* High sensitivity to ammonia
* Quick response to low concentrations of
ammonia
* Uses simple electrical circuit
* Ceramic base resistant to severe
environment
The figure below represents typical sensitivity characteristics,
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 50ppm of ammonia
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 50ppm of ammonia
at various temperatures/humidities
Ro = Sensor resistance at 50ppm of ammonia
at 20°C and 65% R.H.
Temperature/Humidity Dependency:Sensitivity Characteristics:
Features:
The sensing element of TGS826 is a metal oxide 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 TGS826 has high sensitivity to ammonia gas. The sensor can detect concen-
trations as low as 30ppm in the air and is ideally suited to critical safety-related
applications such as the detection of ammonia leaks in refrigeration systems and
ammonia detection in the agricultural field.
0.1
1.0
10.0
-30 -20 -10 0 10 20 30 40 50
Rs/Ro
Ambient Temperature (°C)
0%
20%
40%
65%
100%
RH%
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.
19.5 ± 0.5
1.0 ± 0.05
13.5 + 0.3
- 0.2
9.5 ± 0.3
11.0 ± 0.2
23.0 ± 1.0
3.0 ± 0.2
6.5
± 0.2
6
3
4
25
1
45˚
45˚
Structure and Dimensions:
1 Sensing Element:
Metal oxide is sintered to form a thick film
on the surface of an alumina ceramic
tube which contains an internal heater.
2 Sensor Base:
Alumina ceramic
3 Flame Arrestor:
100 mesh SUS 316 double gauze
Pin Connection and Basic Measuring Circuit:
The numbers shown around the sensor symbol in the circuit diagram at the right
correspond with the pin numbers shown in the sensor's structure drawing (
above
).
Since the sensor has a polarity, DC voltage is always required for circuit voltage (
a
white dot indicates pin 2
). When the sensor is connected as shown in the basic
circuit, output across the Load Resistor (VRL) increases as the sensor's resistance
(Rs) decreases, depending on gas concentration.
Basic Measuring Circuit:
Specifications:
Sensor Resistance (Rs) is calculated by
the following formula:
REV: 05/04
Pin #2 is indicated by a white dot on the
sensor's base.
Power dissipation across sensor electrodes (Ps)
is calculated by the following formula:
Special Note: A more narrowly defined range of Rs or Rs/Ro
will be indicated on each production lot (see Appendix).
Preselected ranges of Rs or Rs/Ro are not available.
Rs = ( -1) x RL
VC
VRL
Ps = VC2 x Rs
(Rs + RL)2
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FIGARO ENGINEERING INC.
1-5-11 Senba-nishi
Mino, Osaka 562-8505 JAPAN
Phone: (81)-72-728-2561
Fax: (81)-72-728-0467
email: figaro@figaro.co.jp
