H24.0.01.6C-07 page 3 of 4
The pH-electrode:
All electrodes are delivered checked and ready for measuring. The warranty period is
6 months
for appropriate treating.
Introduction:
pH electrodes are wearing parts, which - depending on the chemic and mechanic stress they are subjected to - have to be
replaced as soon as the values required can no longer be maintained even after a most thorough cleaning and regeneration.
Please take into account that various substances in hydrous solutions may attack glass and that certain chemic
substances and the KCl solution in the electrode may cause a chemic reaction leading to the blocking up of the diaphragm.
Examples: - When coming into contact with solutions containing proteins, as may be the case when conducting
measurements in the medical and biological field, KCl can cause denaturation of the protein.
- Coagulated lacquers
- Solutions containing a larger concentration of silver ions
Problems may also occur when conducting measurements in low ion media containing solvent. Some of the problems
occurring in such media can be prevented by using a double-chamber electrode with suitable jumpering electrolyte (type
depending on application). Our type GE 103.
As they will influence the measurements, any deposits that may accumulate on the measuring membrane or diaphragm
have to be removed regularly, eg by means of an automatic cleaning device.
Special electrodes for various applications:
1.
Measurements in low ion media
(rain water, water in aquariums, de-mineralised water)
Our type GE 104 (special faceted electrode
for >50µS/cm) or GE 106 (>100µS/cm
).
2.
Sea water aquariums
Standard combined measuring and reference electrodes with 3 mol/l KCl (
Our types GE 100 or GE 014
).
3.
Photographic laboratories
Use double chamber electrode, with jumpering electrolyte (1 molar potassium nitrate solution); potassium nitrate
solution has to be replaced as and when required. Fill watering cap with potassium nitrate solution for storage of
electrode (
Our type GE 103
).
4.
Swimming pools
Standard pH electrode with 3 mol/l KCl (
Our types GE 100 or GE 014
).
5.
Soil examinations
Glass electrode with several diaphragms (
Our type GE 101
). Use prick lance first!
Points to be observed during measuring:
As resistance values (resulting from both the pH electrode and from the measuring device) are generally very high when
conducting pH measurements, the electrode should not be hand-held but put down during the measuring operation in
order to avoid a shift in voltage parameters between the electrode and the measuring device.
In case there is no suitable place where to position the device during measuring, we recommend that the device is held as
far away from the plut as posible and that there is as little movement as possible. Holding the electrode in one hand and
the device in the other, could also help to minimise a shift in voltage parameters.
Make it a rule never to touch the device near the sensor plug as your hand may cause autocapacitance coupling resulting
in measuring inaccuracies. Sudden jumps and changes in the values given on the display when touching or shaking the
plug are not normally due to a loose contact in the plug but result from capacitance changes caused by interference from
hand contact.
In order to check calibration repeat procedures for calibration points 1 and 2 using corresponding turning knob for re-adjustments.
In case you did not prepare pH 4.0 but another buffer solution, eg pH 10.0 or pH 12.0, the corresponding value (pH 10.0 or
pH 12.0) can be set (calibration of second calibration point) using the left-hand turning knob (pH X).
Please note that for each and every calibration procedure the buffer solution value pH 7.0, ie 7.00, has to be set by means of
the right-hand turning knob (ph 7).
Note: We recommend to re-calibrate the measuring device prior to each new measuring series to ensure
optimum accuracy. It has to be considered that the calibration solution and the media to be measured
should had similar temperatures!
After completion of measurements fill electrode protection cap with 3 mol/l KCl solution and slip it back onto electrode.
(Gentle squeezing of the cap displaces air, thus allowing cap to be slipped on easily)
Attention:
pH-electrodes are extremely delicate and sensitive measuring elements. Prior to using the pH electrode, please
carefully read corresponding maintenance and measuring manual!
We shall not assume any warranty if customer failes to use proper care and skill (eg breaking of
electrode, drying-out, blocking etc.).
