MODEL 5081-A
SECTION 12.0
CALIBRATION - OzONE
12.2 PROCEDURE — zEROING THE SENSOR USING THE REMOTE CONTROLLER
1. Place the sensor in the zero standard (see Section 12.1). Be sure no air bubbles are trapped against the mem-
brane. the sensor current will drop rapidly at first and then gradually reach a stable zero value. to monitor the
sensor current, go to the main display. Press dIAG followed by NEXt. the
SEnSor Cur
prompt appears. Press
ENtER to view the sensor current. Note the units: nA is nanoamps; µA is microamps. typical zero current for
an ozone sensor is -10 to +10 nanoamps.
A new sensor or a sensor in which the electrolyte solution has been replace may require several hours (occa-
sionally as long as overnight) to reach a minimum zero current. do Not StARt tHE ZERo RoutINE uNtIL
tHE SENSoR HAS BEEN IN ZERo SoLutIoN FoR At LEASt tWo HouRS.
2. Press CAL on the remote controller.
3. the
SEnSor O
prompt appears. Press ENtER.
4. the screen shows the value (in units ppm) below which the reading
must be before the zero current will be accepted. the screen shows
0.02
. therefore, the reading must be below 0.02 ppm before the zero
will be accepted. For a typical ozone sensor, 0.02 ppm corresponds to
about 7 nA. to change the zero limit value, see Section 7.6.3. Press
ENtER.
NOTE
the number shown in the main display may change. during the
zero step, the previous zero current is suppressed, and the con-
centration shown in the main display is calculated assuming the
residual current is zero. once the transmitter accepts the new zero
current, it is used in all subsequent measurements.
5. the
tiME dELAy
message appears and remains until the zero current
is below the concentration limit shown in the previous screen. If the cur-
rent is already below the limit,
tiME dELAy
will not appear. to bypass
the time delay, press ENtER.
6.
O donE
shows that the zero step is complete. Press EXIt.
7. Press RESEt to return to the main display.
CALIBRAtE
0 dOne
EXIt
CALIBRAtE
Sensor 0
EXIt
NEXt ENtER
CALIBRAtE
time delay
EXIt
ENtER
CALIBRAtE
0 at
0
.02
EXIt
ENtER
83
