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OXIDATION AND DISINFECTION 10.59

The catalytic reaction is very rapid, and empty-bed contact times are on the order of
1 rain. The preheater primarily functions to eliminate moisture from the incoming gas,
and is typically designed for a 20 ° F (-8 ° C) temperature rise to reduce the relative hu-
midity from 100% to about 50%. The thermal/catalytic destruct systems are capable of
reliably reducing off-gas ozone concentrations to well below 0.1 mg/L.

Construction Materials for Ozone Equipment
In designing systems for ozonation, the highly aggressive character of ozone should be
kept in mind. All rubber, most plastics, neoprene, ethylene-propylene-diene rubbers, and
aluminum are unacceptable materials for use with ozone. The only acceptable materials
are 316 stainless steel, 305 stainless steel, glass, Hypalon, Teflon, and concrete. There is
some dispute about the usefulness of type 1 PVC. Manufacturers have often recommended
type 1 PVC, but its quality does not seem to be uniform from place to place, and inci-
dents of PVC failure occur regularly.

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