Viscous and quickly hardening media (such as e.g. paints, lacquers, adhesives, resins, etc.) present operators and planners with special challenges. Incorrect design of pumps and systems repeatedly cause unexpected failures when these substances are pumped. This is due to the particular physical properties that directly act on the pumping process. Such media frequently leave deposits similar to a glazing on parts of pumps and systems coming into contact with the liquid, which causes problems, especially on sealing elements of rotating displacement pumps. Residues occur on the sealing surfaces of the mechanical seal, which are formed within a very short time and become instruced. The pump starts to leak after a short operating period.
From experience it is obvious that oscillating displacement pumps are also not immune against this kinds of problems. Here, too residues can be formed on the check balls and valve seats, which lead to failures after a short period of operation. A poor flowing behaviour of the medium and intake problems in the suction line additionaly have a negative influence on the service life of the pump.
Finally, pipes and connecting elements can block if the substance to be pumped hardens in the environmental air, thus clogging the crosssections of the pipe. Before the system can be decommissioned for a longer period of time, the pumping line must be completely emptied and flushed with a suitable, usually flammable solvent.
A firm grip in viscous and quickly hardening media
Lutz presents its new vertical eccentric screw pump, series B70V-HD, which was specifically developed for pumping quickly hardening viscous materials from mobile containers. The special features include a separate circulation/flushing line, which prevents material deposits around the mechanical seal by means of permanent flushing. The sealing surfaces made of the material combination silicium carbide / silicium carbide as well as the rotor and stator element in the pump foot are designed for an independent direction of rotation during operation. In combination with drive motor with reversible direction of rotation, the pump and the pressure pipe can be easily emptied and subsequently flushed with a suitable solvent.