Convotherm OEB Series Service Handbook page 176

Service Handbook OEB/OES/OGB/OGS
6.16 Problem case: cloudy glass panels - glass corrosion
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Information – What is glass corrosion?
If the inner glass panel is covered in a milky-grey cloudiness, that can no longer be
removed with lime remover, it is from glass corrosion.
What causes glass corrosion?
The cloudiness is caused by the dissolving of sodium, potassium or barium ions
from the glass surface. What remains is a coating with a varying refractive index,
which is seen as cloudiness to the human eye. The cloudiness is usually unevenly
distributed over the entire glass panel, especially beginning on heavier spots or
scratches.
The cloudiness process is accelerated by:

Water that is too soft:
Water that is too soft dissolves ions more quickly from the glass.

The use of water softener systems:
Water from a water softening system has a greater sodium ion content and
dissolves ions more quickly from the glass.

Alkalizing cleaning solution:
The incorrect use and/or amount of cleaning solution can damage the surface
of the glass.

Corrosion protection solution in the water supply:
As a rule, this usually means the use of phosphate silicate products that are
released into the water from a system on-site. These products develop a
protection against corrosion for the water pipes. Unfortunately, these silicates
develop a non-removable coating on the glass panel („glass-on-glass-
coating").
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Information – Solving the problem

Because glass corrosion means irreversible damage, the inner glass panel
must be replaced.

To avoid this happening again, the following prevention measures must be
carefully followed.
AS/11-2011 6_16e_Problem case cloudy glass panels - glass corrosion_b
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