Installation and operating manual for WATERFRIEND exclusive MRD-2 Page 22 (44)
Once the sensors have been connected, every input must be calibrated during initial start-up. Calibration is
necessary even if an electrode is replaced by a new one. The WATERFRIEND checks the calibration procedures
for plausibility during the process (slope and offset). Non-calibrated and "badly" calibrated measurement inputs
are displayed in plain text.
Time delays occur due to the electrode start-up times when the device is switched on.
Buffer solution
The use-by date must be observed for the buffer solutions The solutions must always be stored in a cool, dark
place. Buffer solutions may not be soiled during use. For this reason, electrodes may not be immersed in different
buffer solutions successively without cleaning them with distilled water first. It is also important not to rub the
electrodes with a cloth, because this causes static charging and incorrect measurements. The necessary
buffer solutions for pH 4, pH 7 and for ORP 468mV and
spare electrodes are available from the
"WATERFRIEND“ metering unit supplier.
Electrodes
The electrodes must be free of impurities, oils and fats etc before they are inserted in the flow fittings.
Furthermore, the diaphragms (small spots at the probe point) must be free of coatings, soiling and crystallisation
deposits. Do not touch the glass body with your hands to avoid impurities.
Calibrating the pH electrode
The pH electrode can generally be calibrated as a 1-point calibration. This can be done using the pH 7 buffer
solution, or, on the fly; be done with the help of a photometer.
If the measured values deviate significantly, a 2-point calibration with 2 buffer solutions can also be carried out.
The buffer solutions used must be free of impurities and fresh.
Calibrate current working point or upper value (pH 7).
Procedure:
Press the "MENU" key
Move the cursor (blue backed text) to the line "set pH" by pressing the keys
or
.
Press the
OK
key.
Move the cursor (blue backed text) to the line "calibration" by pressing the keys
or
.
Press the
OK
key.
If the calibration is to be carried out using a photometer during
operation as a one-point calibration, the actual pH value of the
pool water should now be determined using a photometer. If
the calibration is to be carried out using buffer solutions, the
pH electrode must be unscrewed from the flow fitting and then
immersed in the green "pH 7" buffer solution.
Press the „NEXT“ key.
If a calibration is carried out at a pH value that deviates from
pH 7, this value must first be entered after pressing the
"BUFFER SOL." button.
The display shows the current values of the pH electrode
(based on the last calibration). Only when the value shown on
the display no longer changes (this takes several minutes), the
reference value may be saved with the "OK" or "Next" button.
7,20
800
721
675
D -2%
D +10%
pH
mV
Immerse pH electrode
in the buffer solu-
tion pH 7 or measure
the current pH value
with a photometer...
pH X.XX buffer soluti.
pH X.XX meas. signal