Mechanism

How does red rust form?

Red rust forms inside iron water pipes when the iron is in direct contact with water and oxygen. In other words, red rust forms when iron is deprived of electrons.

Red rust, FeO(OH), forms when iron reacts with water (H2O) and oxygen (O2).

Red rust dissolves to water easily and causes discoloration, clogging, corrosion and pipe deterioration, which symptoms lead to water leak.

How to stop formation of red rust

The other way around, the formation can be stopped if electrons are supplied to iron that lost electrons.

This method is called an electrolytic protection.

How red rust is reduced to black rust.

Existing red rust can be reduced to magnetite by supplying electrons to it continuously.

Black rust is passive as a substance: it is highly resistant to oxidation and does not dissolve in water. Its cubic size is 1/10 of that of red rust. Magnetite functions as protective coating on inner surface of pipework. This extends life span of it for more than 40 years.

Disadvantages of conventional pipe cleansings

Conventional pipe cleansing methods, such as flush-out and chemical cleansing, cause red rust to flow out of pipework. They are just putting off the problems. Moreover, a flush-out reduces pipe thickness and wears out inside piping and eventually accelerates further formation of red rust that shortens the life span.