Datasheet

9. TIME DEPENDENCY CHARACTERISTICS
Fig:ll shows a.typical Pattern for a TGS #813 Sensor which has been stored
unenergized for a long period of.time.
This graph Shows Sensor resistance
at a constant gas concentration.
When the Sensor is energized after a lang
storage period it takes approx-
imately 1-10 days for the Sensor to resch a stable resistance level.
Please note,
that the actual transitional time necessary to resch stability
is dependent on the amount of time the Sensor has been stored and the
atomospheric conditions under which it has been stored.
.'
Table ID suggested that the Sensor be conditioned for at least 7 days Prior
to testing and evaluation.
This period is necessary because of the phenomenon
illustrated in Fig.11.
. L
Caution at Calibration Time
.
Regardingtheabove characteristics
of the Sensor, we strongly recommend that
you wait until the Sensor has reached a stable output level before you
calibrate.
Failure to do so may result in non-Standard Sensor perfromance.
I
@ Initial and transitional period a?ter switch on.
@ Stabillzed period of energited output level.
&
1.0 -.-
a
Ib:
.+ ‘,.‘,. *, :,
/
m
1 hour after
restoration of
current input
1-l Odays after
restoration of
cunent input
Time
FIG. 11. TYPICAL PATTERN OF TGS $813 SENSITIVITY
CHANGE WITH TIME.
+Remarks; Ro: Sensor resistance at stabiiited level.
Fl: Sensor resistance during s?abilization.
(13)