Electrolytic Corrosion In Swimming Pools - Calorex PPT8 Installation Manual

Installation Manual
PPT8/12/16/22L/LY

4.0 Electrolytic Corrosion in Swimming Pools

Calorex Heat Pumps Ltd. · The Causeway, Maldon, Essex CM9 4XD, UK · Tel: +44 (0)1621 857 171
Electrolytic corrosion will occur when dissimilar metals that are in
contact with each other create a potential difference between
themselves. Sometimes separated by a conductive substance
known as an electrolyte, the dissimilar metals will create a small
voltage (potential difference) that allows the ions of one material to
pass to the other.
Just like a battery, ions will pass from the most positive material to
the more negative material.
Anything more than 0.3 volts can cause the most positive material to
degrade.
A swimming pool with its associated equipment can create this ef-
fect. The pool water being an ideal electrolyte and components of
the filtration circuit, heating system, steps, lights etc providing the
dissimilar metals needed to complete the circuit.
Whilst these small voltages are rarely a safety threat, they can cre-
ate premature failure through corrosion. Not dissimilar to corrosion
through oxidation, electrolytic corrosion can cause complete failure
of a metallic material in a very short period of time.
In order to prevent this type of corrosion all metallic components in
contact with swimming pool water should be bonded together using
10mm² bonding cable. This includes non-electrical items such as
metal filters, pump strainer boxes, heat exchangers, steps and hand-
rails. It is highly recommended that bonding be retrofitted to existing
pools, which may not be protected by this system.
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