Process for preventing encrustations on surfaces which are in constant contact with aqueous solutions containing matter prone to crystallize

Method for preventing the deposit of precipitated crystalline materials on the surface of measuring equipment receivers for equipment in power plant gas desulfurizing installations, whose measuring cell is flowed through by a material tending to crystallize out containing aqueous liquid for measuring the physical or chemical properties of this liquid, characterized by the fact that the liquid flowing to the measuring receiver has a chemical substance conducted into it which forms a thin protective film on the surface to be protected, and further

• characterized by feeding solution from a container to an electrode in the measuring cell and pumping the chemical substance by a proportioning pump into the liquid immediately before it flows into the measuring cell, and flowing liquid and the chemical substance in the measuring cell through small openings in a glass tube surrounding a second electrode in the measuring cell, said glass tube constituting a surface upon which the thin film is formed.