Testing The Sensor Via A Transmitter - Mettler Toledo InPro 6850 i Bedienungsanleitung

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If the green LED lights up the current for air
m easurement is with i n the admissible range.
If the LED does not light up, you should check the
battery of the O
manual "Accessories"). If the battery is working, than
there is probably a problem with your sensor. You
should change the electrolyte and/or the m embrane
body of your sensor. If after a m embrane change
the LED still does not light up, this means that there
is maybe something wrong with the interior body of
the sensor. You should then change it (see "Section
6.2").
a
Important! The Sensor Check function only verifies
the correctness of the electrode current for air
measurement. In order to be absolutely sure of the
functionality of the sensor, the residual signal in
an oxygen free medium should also be controlled
(see "Section 6.1.3").

6.1.3 Testing the sensor via a transmitter

A periodic zero current measurement (no zero point
calibration!) is recommended for verification of
proper sensor function.
h
Note: At the time you carry out the zero current
measurement, the sensor must be polarized.
Zero current measurement can be done by using
z ero i ng gel (order no. 34 100 1032) or nitrogen
(N ) or carbon dioxide (CO
2
with a p urity of at least 99.995 %, alternatively in a
sample m edium saturated with one of these gases.
After 2 minutes in an oxygen-free sample medium,
the reading on the transmitter should drop to below
10 % of the reading in ambient air, and within
10 minutes the value should have dropped to below
1 %.
If the measured values are too high, this suggests
a depleted electrolyte or a defective membrane. In
the first instance replace the electrolyte, and in the
second case exchange both the membrane body and
the electrolyte accordingly.
If after such procedures the above mentioned values
are still not reached, replace the interior body. If
this doesn't solve the problem too send the sensor
to your local METTLER TOLEDO representative for
inspection.
Many sample media contain volatile substances
which, even at very low concentrations, have a
c learly perceptible smell. Similarly to oxygen, these
s ubstances are able to invade the electrolyte through
the gas-permeable membrane. Accordingly, they
b ecome noticeable when changing the electrolyte.
In most cases, such substances have absolutely no
InPro 6850 i / 6900 i / 6950 i
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InPro 6850 i / 6900 i / 6950 i O
sensor master (see instruction
2
Sensor 12 / 25 mm
2
) calibration gases
2
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Printed in Switzerland