BARTEC BENKE HYGROPHIL H 4230-12 Ex Zone II, Руководство по эксплуатации, Страница: 69 / 112

Maintenance
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Operating Instructions HYGROPHIL® H 4230-12 BA 060207
6.3.2 Types of dirt
The measuring chamber may be contaminated in particular by the following
types of dirt:

Oils and grease
Due to the high temperature of the air to be measured, these substances are
often present in a gaseous state and are therefore able to pass through the
filter. In the cooler measuring chamber they condense and, after a certain
amount of time, form a layer that may block the air ducts. This can be de-
layed considerably by adding the surfactant correctly. Despite this, evapora-
tion in the measuring cell is not prevented; the surface of the water remains
free of oil and grease thanks to the self-cleaning effect.

Tar
Tar is a fairly problematic form of contamination as the self-cleaning effect
does not work fully in this case. The equipment must be cleaned using suit-
able solvents.

Dust
Dust that is not dissolved by water is deposited on the bottom of the measur-
ing cell. The measuring cell fills with sludge and, after some time, the correct
humid temperature can no longer be formed.
Water-soluble substances and gases that form compounds with water (such
as sulphur dioxide) do not disrupt the evaporation. Measurement errors re-
main within the guaranteed accuracy range.
In order to inspect and clean the measuring chamber and to exchange hos-
es, seals or sensors it is necessary to disassemble and dismantle the meas-
uring chamber.