Q12. How does it reduce red rust to black rust?

Corrosion is generally formed inside iron pipes when iron is deprived of electrons with direct contact with water and oxygen. The iron is then converted to ferrous hydroxide {hydroxide oxide ion, FeO(OH)} to cause issues regarding corrosion inside water pipes.
The Pipetector breaks up water clusters smaller with the use of phenomenon of nuclear magnetic resonance to relocate free electrons of water (hydrated electrons). In detail, when a certain amount of water flows inside pipes with kinetic energy caused by water pumps and free-fall from elevated tanks for example, the hydrated electrons are likely to change their location from inside the water clusters to the outside. These electrons then function to reduce internal red rust to black rust and stop further corrosion damage and water discoloration as well.
What you need to keep in mind is that black rust (magnetite) is imbalanced just after it is formed, so if supply of hydrated electrons is stopped, black rust goes back to red rust. The hydrated electrons therefore need to be supplied continuously until layer of black rust is thick enough to be stable. When the layer gains enough thickness, it functions as insoluble and protective coating against further corrosion inside water pipes.