Witam Do budowy detektorów tlenku węgla proponuję czujniki firmy FIGARO TGS2442 lub znacznie prostszy w zastosowaniu w aplikacjach analogowych TGS5042. Czujniki te dostępne są w firmie Maritex www.maritex.com.pl.
FIGARO
PRODUCT INFORMATION
TGS 2442 - for the detection of Carbon Monoxide
Features:
Applications:
* Low power consumption
* High sensitivity/selectivity to
carbon monoxide (CO)
* Miniature size
* Low sensitivity to alcohol vapor
* Long life and low cost
* Low humidity dependency
* CO detectors
* Air quality controllers
* Indoor parking lot ventilation
TGS 2442 utilizes a multilayer sensor structure. A glass layer for thermal insulation
is printed between a ruthenium oxide (RuO2) heater and an alumina substrate. A
pair of Au electrodes for the heater are formed on a thermal insulator. The gas sensing
layer, which is formed of tin dioxide (SnO2), is printed on an electrical insulation layer
which covers the heater. A pair of Au electrodes for measuring sensor resistance
are formed on the electrical insulator. Activated charcoal is filled between the internal
cover and the outer cover for the purpose of reducing the influence of noise gases.
TGS 2442 displays good selectivity to carbon monoxide, making it ideal for CO
monitors. In the presence of CO, the sensor's conductivity increases depending on
the gas concentration in the air. A simple pulsed electrical circuit operating on a one
second circuit voltage cycle can convert the change in conductivity to an output signal
which corresponds to gas concentration.
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 in 100ppm CO
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 30ppm, 100ppm and 300ppm
of CO at various temperatures and 50%R.H.
Ro = Sensor resistance at 300ppm of CO
at 25°C and 50% R.H.
Sensitivity Characteristics:
100
Air
Temperature/Humidity Dependency:
1000
Ethanol
10
50%RH
100
Rs/Ro
Rs/Ro
H2
1
Air
10
CO 30ppm
0.1
1
CO
CO 100ppm
CO 300ppm
0.01
1
10
100
1000
Gas Concentration (ppm)
10000
0.1
-20
-10
0
10
20
30
40
50
60
Temperature (˚C)
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.
Basic Measuring Circuit:
Circuit voltage (VC) is applied across the
sensing element which has a resistance (Rs)
between the sensor’s two electrodes (pins
No. 2 and No. 3) and a load resistor (RL)
connected in series. The sensing element
is heated by the heater which is connected
to pins No. 1 and No. 4.
Heating cycle --The sensor requires
application of a 1 second heating cycle which
is used in connection with a circuit voltage
cycle of 1 second. Each V H cycle is
comprised by 4.8V being applied to the
heater for the first 14ms, followed by 0V
pulse for the remaining 986ms. The Vc cycle
consists of 0V applied for 995ms, followed
by 5.0V for 5ms. For achieving optimal
sensing characteristics, the sensor's signal
should be measured after the midpoint of
the 5ms Vc pulse of 5.0V (for reference, see
timing chart below).
NOTE: Application of a Vc pulse condition
is required to prevent possible migration of
heater materials into the sensing element
material. Under extreme conditions of high
humidity and temperature, a constant Vc
condition could result in such migration and
cause long term drift of Rs to higher values.
A 5ms Vc pulse results in significantly less
driving force for migration than a constant
Vc condition, rendering the possibility of
migration negligibly small.
Structure and Dimensions:
unit: mm
Top View
Specifications:
Model number
TGS 2442
Sensing element type
M1
Standard package
TO-5 metal can
Target gases
Carbon monoxide
Typical detection range
ø9.2±0.2
ø8.1±0.2
ø0.3
30 ~ 1000 ppm
Heater voltage cycle
Circuit voltage cycle
VC
VC=0V for 995ms,
VC=5.0V±0.2V DC for 5ms
RL
variable (≥10kΩ)
Heater resistance
RH
17 ± 2.5Ω at room temp.
Heater current
IH
approx. 203mA(in case of VHH)
Heater power
consumption
PH
approx. 14mW (ave.)
Sensor resistance
Rs
6.81 kΩ ~ 68.1 kΩ in 100ppm of
carbon monoxide
Sensitivity
(change ratio of Rs)
Electrical characteristics
under standard test
conditions
VH
Load resistance
Standard circuit
conditions
VHH=4.8V±0.2V DC, 14ms
VHL=0V, 986ms
β
0.23 ~ 0.49
Vcx RL
Vout
- RL
The value of sensitivity (β) is calculated with two measured
values of Rs as follows:
β = Rs (CO,300ppm)
Rs (CO,100ppm)
ø0.55±0.05
Code:
4
1
3
2
& gt; 2 days (under review)
To facilitate usage of this sensor, TGS2442 is shipped in
presorted groupings which have a more narrowly defined
range of β:
A: 0.23 ~ 0.34
B: 0.26 ~ 0.37
C: 0.29 ~ 0.40
1: 6.81 ~ 21.5kΩ
2: 10.0 ~ 31.6kΩ
ø5.1±0.1
Bottom view
D: 0.32 ~ 0.43
E: 0.35 ~ 0.46
F: 0.38 ~ 0.49
The above six classification will be further subdivided into the
following rankings of Rs values in 100ppm of CO:
Code:
REV: 6/00
1.5
45˚
Same as Std. Circuit Condition
(above)
Conditioning period before
test
Rs =
12.7±0.5
0.2
Carbon monoxide in air
at 20±2˚C, 65±5%RH
Circuit conditions
Sensor resistance (Rs) is calculated with a measured value of
Vout as follows:
ø6.0+0,-0.3
10.0±1.0
Test gas conditions
Standard test conditions
5.9
3: 14.7 ~ 46.6kΩ
4: 21.5 ~ 68.1kΩ
FIGARO ENGINEERING INC.
1-5-11 Senba-nishi
Mino, Osaka 562
JAPAN
Phone: (81)-727-28-2561
Fax:
(81)-727-28-0467
email: figaro@figaro.jp.org