TGS 832 - for the detection of Chlorofluorocarbons (CFC's)
PRODUCT INFORMATION
Features:
* High sensitivity to R-134a
Applications:
* Refrigerant leak detector
* Quick response to R-134a
* Improved selectivity
* Long term stability
* Uses simple electrical circuit
* Ceramic base resistant to severe
environment
The sensing element of Figaro gas sensors is a tin dioxide (SnO
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 832 has high sensitivity to R-134a, the most promising alternative to R-12,
commonly used in air conditioning systems and refrigerators. R-12 and R-22 are also
detectable by TGS 832. With its good long term stability, TGS 832 is an excellent,
low-cost sensor for CFC detection.
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
resistance ratio
(Rs/Ro) which is defined as follows:
sensor
Rs = Sensor resistance of displayed gases at
various concentrations
Ro = Sensor resistance at 100ppm of R-134a
2) semiconductor
The figure below represents typical temperature and humidity
dependency characteristics. Again, the Y-axis is indicated as
sensor resistance ratio
Rs = Sensor resistance at 100ppm of R-134a
Ro = Sensor resistance at 100ppm of R-134a
(Rs/Ro), defined as follows:
at various temperatures/humidities
at 20°C and 65% R.H.
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
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.
Standard Circuit Conditions:
metIlobmySseulaVdetaRskrameR
egatloVretaeHVH0.5 ±V2.0CDroCA
egatloVtiucriCVCV42.xaM
ecnatsiseRdaoLRLelbairaVSP*≤Wm51
CDroCA
SP*≤Wm51
SnO2 is sintered to form a thick film on
the surface of an alumina ceramic tube
which contains an internal heater.
Alumina ceramic
100 mesh SUS 316 double gauze
Basic Measuring Circuit:
).
Electrical Characteristics:
metIlobmySnoitidnoCnoitacificepS
ecnatsiseRrosneSsRa431-Rta01/mpp0ari4kΩ4~0kΩ
fooitaRegnahC
ecnatsiseRrosneS
ecnatsiseRretaeHR
noitpmusnoCrewoPretaeHP
oR/sR
H
H
Standard Test Conditions:
TGS 832 complies with the above electrical characteristics
when the sensor is tested in standard conditions as specified
below:
Test Gas Conditions:20°±2°C, 65±5%R.H.
Circuit Conditions:VC = 10.0±0.1V (AC or DC),
VH = 5.0±0.05V (AC or DC),
RL = 10.0kΩ±1%
Preheating period before testing: More than 7 days
FIGARO USA, INC.
3703 West Lake Ave. Suite 203
Wilmette, Illinois 60091
Phone: (847)-832-1701
Fax:(847)-832-1705
email: figarousa@figarosensor.com
REV: 8/92
)ria/mpp003taa431-R(sR
)ria/mpp001taa431-R(sR
5.056.0~0
erutarepmetmooR0.03±0.3Ω
V
H
V0.5=538±09Wm
Sensor Resistance (Rs) is calculated by
the following formula:
Rs = (-1) x R
VC
VRL
L
Power dissipation across sensor electrodes (Ps)
is calculated by the following formula: