TGS2442 Datasheet, PDF (9/25 Pages) List of Unclassifed Manufacturers – Detection of Carbon Monoxide

TECHNICAL INFORMATION FOR TGS2442
3-5 Initial action
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Figure 11 shows the initial action of the sensor’s
resistance. For purposes of this test, the sensor was
stored unenergized in normal air for 40 days after
which it was energized in clean air.
After energizing, the sensor’s resistance reaches to
1
90% of its final value in less than one minute, an alarm
delay circuit should be incorporated into detectors
using TGS2442 to prevent activation of an alarm
during this period.
0.1
0
5
10
15
20
25
30
Time (min.)
Figure 11 - Initial action
(Ro = Rs after 20 minutes of energizing)
3-6 Influence of unenergized storage
Figure 12 shows the influence of unenergized storage
on sensor resistance. Sensors were stored
unenergized in normal air for 30 days after which
they were energized. The Y-axis represents the ratio
of sensor resistance in various concentrations of
CO␣ after the unenergized period (Rs) to the resistance
in 100ppm of CO after energizing at the rated voltage
for 4 days (Ro).
This chart shows that after energizing, unlike the
sensor resistance in clean air (as shown in Fig. 11),
resistance in CO first decreases slightly and then
returns to a stable level, demonstrating the need for
adhering to the recommended preheating period
prior to calibration.
CO 30ppm
CO 100ppm
CO 300ppm
10
1
0.1
0
2
4
6
8
10 12 14
Time (days)
Figure 12 - Time dependency
(Ro = Rs in 100ppm of CO after 4 days, n=20)
Revised 03/00
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