TGS2442 Datasheet, PDF (10/25 Pages) List of Unclassifed Manufacturers – Detection of Carbon Monoxide

TECHNICAL INFORMATION FOR TGS2442
4. Reliability
Tests conducted in this section demonstrate that TGS2442
can meet the requirements of various testing standards
without incurring adverse long term effects from such tests.
4-1 Interference gas test
Figure 13 shows the results of testing the TGS2442
sensor for durability against various interference
gases specified by GRI Test Protocol 1. The test was
conducted by exposing the sensor to each gas shown
in Fig. 13 (starting with CO 100ppm) for two hours,
then removing the sensor to fresh air for just under
one hour, and followed by inserting the sensor into
the next test gas. This procedure was repeated for
the full range of gases shown in Fig. 13.
Because the sensor is exposed to each of the test gases
consecutively, to some small extent the effect of the
previous test gas may affect subsequent tests for a
short period. However, despite the short-term effects
of such gases remaining after exposure, the sensor
still shows significantly less sensitivity to each test
gas when compared to 100ppm of CO, and CO
sensitivity remains unaffected.
Figures 14 and 15 show data from tests conducted
using interference gases listed in the UL2034 standard
for Selectivity Test (Sec. 38) which are deemed to
represent air contaminants likely to be found in the
vicinity of an installed CO detector. Data for Figure
14 was collected by exposing samples in each of the
test gases for a period of two hours as required by
the UL standard. Sensor resistance at both the initial
point and at the conclusion of test gas exposure was
recorded. When compared to the sensor’s measured
resistance in 100ppm of CO (Ro), in all cases the
resistance in test gas remained at more than 40 times
that of resistance in 100ppm of CO, showing the
sensor to have negligible influence by these gases.
Figure 15 demonstrates that sensor subjected to the
interference gas tests do not change their
characteristics after exposure to these gases. Samples
subjected to the interference gas test were compared
to reference samples (not subjected to the interference
gas tests). Over a two week period, when not
undergoing gas test, all samples were energized in
fresh air under standard circuit conditions.
This data suggests that TGS2442 shows good
durability against every gas used in GRI Test Protocol
1 and meets the requirements of UL2034.
100
80
60
40
20
0
CO _{10M0eptphmaBnueta5n0He0ep3pp0tm0aEpnptehmy5l0aI0scpoepptmarotCepOa2n20o05Alp02mp00mm00ppopApnmcmiaet1o0En0etph2pa0mnT0oopllp2um0e0nTperipc2mh0lo0NrpoiptremicthNoaxintiredoeu2Es05t00hoppyxppliedmmCneOe2201000A0p0cppprpmypmlmic cement 10g}
Fig. 13 - Effects of interference gases (GRI Test Protocol 1)
(Ro = Rs in CO 100ppm)
80
initial value
after 2 hrs.
70
60
50
40
30
20
10
0
Methane
500ppm
Isobutane
300ppm
Heptane CO2 Ethyl acetate Isopropanol
500ppm 5000ppm 200ppm 200ppm
Figure 14 - Selectivity test (UL2034, Sec. 38)
(Ro = Rs in CO 100ppm)
100
CO 30ppm (ref)
CO 100ppm (ref)
CO 300ppm (ref)
test
CO 30ppm (test)
CO 100ppm (test)
CO 300ppm (test)
10
1
0.
0
2
4
6
8
10
12
14
Time (days)
Figure 15 - Stability of sensors subjected to selectivity test
(Ro = Rs in CO 100ppm on Day 6)
Revised 03/00
8