English (GB)
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3. General information
These installation and operating instructions contain all
information important for users of the AQC-D5 preassembled
system:
• technical data
• instructions on commissioning, use and maintenance
• safety information.
Should you require further information or should you encounter
problems that are not handled in sufficient depth in this manual,
please contact Grundfos.
We shall be pleased to support you with our comprehensive
know-how in the fields of measuring and control technology as
well as water treatment.
We always welcome suggestions on how to optimise our
installation and operating instructions to satisfy our customers.
4. Safety
4.1 Obligations of the owner/operations manager
The owner/operations manager is responsible for:
• compliance with country-specific safety regulations
• training of operating personnel
• provision of prescribed protective gear
• implementation of regular maintenance.
The product has been constructed and tested in accordance with
safety protective measures for electronic equipment and has left
the works in perfect condition satisfying safety requirements.
To maintain this condition and to ensure safe operation of the
instrument, the user is obliged to observe the notes and warnings
given in these installation and operating instructions.
If safe operation cannot be guaranteed any longer, the product is
to be put out of service and safeguarded against unintentional
operation. This is the case:
• if the product shows visible damage
• if the product seems to be inoperative
• after a long storage time under unfavourable conditions.
4.2 Avoidance of danger
5. Function and applications
The AQC-D5 preassembled system consists of the following
components:
• potentiostatic measuring cell AQC-D5
• measuring amplifier and controller Conex
®
DIA
• peristaltic pump
• sample water deficiency sensor 96680752 (12.4134-1).
Various oxidation agents are used for the disinfection of
swimming pool water and drinking water, for example chlorine
(Cl
2
).
It is necessary to measure the concentration of the oxidation
agent and regulate its dosing because the disinfection effect is
too weak at too low concentrations.
Too high concentrations result in:
• danger to health
• unpleasant odour and taste
• corrosion damage
• increased operating costs.
Free residual chlorine is defined as the sum of molecular chlorine
gas (Cl
2
), hypochlorous acid (HOCl) and the hypochlorite anion
(OCl
–
).
A buffer solution is added to the sample water by the pump to
adjust the pH value of the measuring water to pH 4.5.
Fluctuations of the pH value and their effect on the measuring
water are being compensated, and it is possible to measure free
chlorine in measuring water with values > pH 8.5. Only about
4.5 litres per hour are treated with the buffer solution. After a
chemical reaction, the concentration is measured
electrochemically.
The basic element of the AQC-D5 preassembled system is the
potentiostatic measuring cell AQC-D5.
Electrode cleaning motor
The measuring electrode and the counter-electrode are
continuously cleaned of deposits by a gentle, yet effective
cleaning motor.
• This guarantees a uniform sensitivity for the measuring cell for
a long time.
• The motor drives a magnetic stirring stone by a magnetic
clutch.
• The cleaning balls, which are constantly kept in motion by the
magnetic stirring stone, circulate between the measuring
electrode and the counter-electrode.
Influence of temperature
The current generated on the electrodes depends on the
temperature of the sample water.
• The measured value increases by approximately 5 % per 1 °C.
• Temperature variations are compensated in the measuring
amplifier.
– The temperature can be measured using a Pt100
temperature sensor.
– The temperature measuring signals are transferred to the
measuring amplifier and calculated using the electrode
signals.
Influence of pH value
The pH value is always constant (pH 4.5) in the AQC-D5
preassembled system due to the buffer dosing. Therefore there is
no influence of the pH value to be taken into account.
If the pH value is measured with a pH electrode, the
measurement takes place before the buffer dosing, so that the
correct pH value of the measuring water value is measured.
Warning
Strictly observe the installation and operating
instructions of the components!
Warning
Do not dismantle the device!
Cleaning, maintenance and repairs must only be
carried out by authorised personnel!
Warning
Other applications than those described in section
are not approved and
not permitted. Grundfos cannot be held liable for any
damage resulting from incorrect use.
