H66.0.01.6C-10
Operating Manual GLF 100
Page 7 of 8
12 General information about conductivity measuring
12.1 The Conductivity Measuring Cell
During the measurement, the conductivity measuring cell must be dipped at least in so far, that
at least 30 mm beginning from the top of the measuring cell, is located in the medium.
The maximum immersion depth for continuous operation should not exceed 110 mm.
The measuring cell can either be stored dry or in water. After dry storage wetting time will be
prolonged slightly. If changing over from one liquid to another with conductivities varying widely
make sure to properly rinse and shake dry measuring cell.
Attention: Measuring cell must never come into contact with water-repellent materials
such as oil or silicone.
If conductivity measured is much higher or lower than expected this may be due to the electrode
being soiled with non-conducting or conducting foreign materials. Measuring cell has to be
cleaned with a watery soap solution.
When measuring media with low conductivities the electrode has to be stirred sufficiently.
12.2 Measuring hints
Conductivity measuring is comparably easy to perform, the precision of the instrument is very
constant if it is used as intended. Depending on the necessary accuracy the instruments can be
used up to several years without recalibration of the cell constant.
If the accuracy should be controlled or improved, this is done by means of suitable reference
solutions and the adjusting of the cell factor.
Attention! Wrong handling of reference solution can make them useless very fast.
12.3 Measuring procedure
Especially when measuring low conductivity: Before immersion to the measuring solution, rinse
the electrode with deionised water, dry with a paper towel and shake remaining water out.
The measuring is speeded up considerably, if the electrode is immersed and pulled out the
solution several times.
Especially when measuring low conductivity the electrode needs sufficient flow during the
measuring, e.g via stirring the solution.
When temperature compensation is activated, the electrode needs enough time to adjust to the
actual temperature of the measuring solution to work accurate.
12.4 Temperature compensation
The conductivity of aqueous solution is temperature dependent. The dependency itself is
strongly dependent on the kind of solution. For the most applications e.g. in fish farming etc., the
non linear temperature compensation of natural waters is precise (“nLF” according to EN
27888). The most common reference temperature is 25 °C.
