H66.0.01.6C-01
Operating Manual GLF100
page 3 of 6
2 General Information About Conductivity Measuring
2.1 The Conductivity Measuring Cell
During the measurement, the conductivity measuring cell must be dipped at least in so far, that at least 30mm
beginning from the top of the measuring cell, is located in the medium.
The maximum immersion depth for continuous operation should not exceed 110mm.
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.
2.2 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.
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.
2.3 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.
2.4 Min-/max- value memory
The lowest and highest measured value since the turning-on of the device will be stored.
Watch MIN value (Lo):
press shortly key
mode
once
display changes between ‘Lo’ and MIN value
Watch MAX value (Hi):
press shortly
mode
once again
display changes between ‘Hi’ and MAX value
restore current value:
press shortly
mode
once again
current value of the chosen unit is displayed
delete MIN/MAX value:
press
mode
for 2 sec.
MIN and MAX values will be deleted, the
display shows shortly ‘CLr’ (clear)
After switching-off and turning-on again all min-/max- values will be deleted.
2.5 Hold – function
When the
hold
– key is pressed, the current measured value will be ‘frozen’ (display symbol: HLD) until the key is
pressed again. Then the device will measure in its normal way again.
