Aquaprobe
®
AP-5000 Instruction Manual
10401-00906 Rev M
When installing an AP-5000, it is important to recognise and avoid the possibility of
creating a situation where galvanic corrosion can occur.
The AP-5000 is made primarily from hard-galvanised marine grade aluminium. All the time
that the aluminium body of the Aquaprobe is insulated from any other type of metal, there
should be no problem with corrosion (unless the Probe is placed in strong acids or alkalis,
for which it is not designed).
Corrosion problems can occur if the Aquaprobe is mounted near to, and connect to a
dissimilar metal, such as stainless steel. Typical examples of this are mounting the Probe
inside a steel pipe or suspending it from a steel dock on a steel wire. In these situations, a
steel-aluminium battery is created that will generate a voltage of around 0.5V and lead to
the corrosion of the metal with the lower potential, in this case the aluminium of the
Aquaprobe.
It is important to avoid creating a situation where galvanic corrosion can occur in
your installation.
The easiest way to do this is by electrically insulating the Aquaprobe
from the supporting structure. This can be done by suspending the Aquaprobe on a Mylar
or Nylon rope rather than a conductive steel wire.
If the Aquaprobe is to be mounted inside a steel pipe, wrap a good thickness of electrical
insulation tape around the top and bottom of the Probe to form ‘fenders’ in order to prevent
the Probe making physical contact with the inside of the pipe. When doing this, ensure that
you do not block any of the holes in the Probe’s sleeve, which are essential for water flow
and correct operation of the Probe.
If the above techniques are not possible and a metal-to-metal connection is unavoidable, a
sacrificial anode must be attached to the Aquaprobe. Sacrificial anodes are manufactured
from zinc and are designed to slide onto the threaded connector section of the Aquaprobe
and to be held on by the mounting nut. Zinc is much more active than aluminium and will
therefore corrode first leaving the Aquaprobe undamaged.
Sacrificial anodes are, as the name suggest, sacrificial, so will need replacing periodically.
Sacrificial anodes are available for all models of Aquaprobes. Please contact Aquaread Ltd
for more details.
2.4. About the Probe Sleeve and Sleeve End Cap
The AP-5000 is constructed with an aluminium sleeve surrounding the delicate sensing
electrodes. The Sleeve can be easily removed by unscrewing to allow cleaning of the
individual electrodes, however,
the Probe sleeve forms an integral, working part of the
Probe’s measurement system, and MUST be fitted for correct operation.
Probe sleeves are also specifically matched to the Probe with which they were supplied.
If
you have more than one AP-5000, be sure not to mix the sleeves up between the
Probes.
Doing so may seriously affect the performance of the EC electrode.
All Aquaread
®
Optical Electrodes are incredibly sensitive. For example, the Turbidity
electrode is capable of measuring between 0 and 3000NTU with an internal resolution of
greater than 0.1NTU. This means that the electrode is able to detect changes in turbidity
that are less than 0.003% of the full range! The other optical electrodes have a similar level
of sensitivity.
© 2019 Aquaread
®
Ltd.
www.aquaread.com
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