Datasheet

Revised 10/12
10
TECHNICAL INFORMATION FOR TGS2620
3-3 Effect of air ow
Figure 18 shows how the sensor signal (VRL) is
affected by air ow. The test procedure involves
situating the sensor in an air stream of 3.1 meters
per second, with the air ow vertical/horizontal to
the ameproof stainless steel double gauze of the
sensor’s housing.
The increase in sensor signal shown in Figure 18
resulted from the decrease in sensor element tem-
perature caused by the air ow. As a result, direct
air ow on the sensor should be avoided.
3-4 Heater resistance durability
Figure 19 illustrates the procedure for testing the ef-
fects of excess voltage applied to the heater. Heater
resistance was measured while the heater was un-
powered and at room temperature.
The results of this test are shown in Figure 20 which
shows the change in resistance of the heater when
various heater voltages (rather than the standard
5.0V) are applied in the absence of gases.
As this section demonstrates, the heater shows good
durability against increased heater voltage. How-
ever, since excessive heater voltage will cause the
sensor’s heater resistance to drift upwards, excessive
heater voltage should still be avoided.
Fig. 18 - Effect of air ow
Fig. 19 - Test procedure for heater durability
121086420
0.2
0.3
0.4
0.5
0.6
0.7
Time (min.)
3.1 m/s air flow vertical 
to double gauze
V OUT (V)
121086420
0.2
0.3
0.4
0.5
0.6
0.7
Time (min.)
V OUT (V)
V C =V H =5V, R L =10kΩ
V C =V H =5V, R L =10kΩ
3.1 m/s air flow horizontal
to double gauze
= 0.92
Rs with air flow of 3.1m/s
Rs without air flow
= 0.91
Rs with air flow of 3.1m/s
Rs without air flow
0
50
100
150
200
250
300
350
400
1 2 3 4 5 6 7 8
Heater resistance (Ω)
Test run
Fig. 20 - Short term effect of VH on RH
5V
6V
7V
8V
9V
10V
Test run 1 2 3 4 5 6 7 8
: RH is measured
10min.
11V