Magnetite (Fe3O4) is also called saturated iron oxide. It is a chemical compound of iron and oxygen and therefore an oxide. For Merus this is relevant in terms of magnetite forming in water systems where the pipe is made of metal.
Merus is treating water systems, which face corrosion problems. In this case corrosion and the forming of magnetite are linked. The The process is as follows:
After installing the Merus Ring, the existing corrosion will be removed downstream the point of installation. The solved rust is carried with the liquid. Once the rust is removed from e.g. a pipe, a layer magnetite is automatically forming on the inner surface. This can be easily seen, as this magnetite is a black layer on the metallic surface. This phenomena of magnetite forming in water or steam pipes, is know from water systems with an oxygen-deficient. In other words, if there is not enough oxygen in the water to finalize the oxidation, then magnetite (Fe3O4) forms, instead of the more common Fe2O3 rust.
In this case F3O4 is very useful. It makes the pipe inert against new corrosion, the black layer is almost like a passivation. This black layer is so stable not even Microbiologically Induced Corrosion – MIC has a chance to harm the steel surface.
Once the magnetite is exposed to enough oxygen, the black layer dissapears after a short time and forms normal rust again. This happens usually when a pipe is without water and open to the atmosphere. If the water comes again and the system is still equipped with the Merus Ring, the corrosion will be removed again and the black layer forms once more in short time.