Detecting Corrosion By Cfcs - Worcester ZSBR 7-28 ICS1 Service Booklet

5.5

Detecting corrosion by CFCs

Halogenated hydrocarbons in the combustion air cause
surface corrosion of the affected metal components.
The combustion chamber and the boiler heating sur-
faces (including stainless steel) are particularly suscep-
tible to this type of attack as are the metal components
in the flue socket, flue joints and the chimney.
The presence of halogenated hydrocarbons in the com-
bustion air results in the production of highly caustic
hydrochloric acid and - depending on the composition
of the combustion air - hydrofluoric acid which build up
inside the boiler and remain active over long periods of
time.
In order to limit the damage, the source of the contami-
nation must be located and sealed off. If this is not pos-
sible, the combustion air must be brought to the
appliance from an unaffected area.
Halogens can occur in the following areas:
Industrial sources
Dry cleaners Trichloroethylene, tetrachlo-
roethylene, fluorinated hydro-
carbons
Degreasing baths Perchloroethylene, trichlo-
roethylene, methyl chloroform
Printers Trichloroethylene
Hairdressers Aerosol propellants, hydrocar-
bons containing chlorine and
fluorine (Freon)
Sources in the home
Cleaning and Perchloroethylene, methyl
degreasing agents chloroform, trichloroethylene,
methylene chloride, carbon
tetrachloride, hydrochloric
acid
Hobby workshops
Solvents and thin- Various chlorinated hydrocarb
ners
Aerosol sprays Chlor-fluorinated hydrocar-
bons (Freons)
Table 9
7 181 465 347 (01.07)
Appendix
49