The Dickow NM centrifugal pump, which is available in the UK from Michael
Smith Engineers, is a magnetically-coupled unit that requires no
mechanical seal arrangement. Suitable for aggressive fluid handling
duties, the pump has large internal clearances between the inner magnets
and containment shell, plus wear-resistant sleeve bearings, allowing the
passage of fluids with some entrained solids. internal circulation within
the pump is taken from behind the impeller at the discharge point,
through the magnet area and pump shaft to the balance holes on the rear
of the impeller. This configuration creates pressure, forcing the
circulation back to the volute casing, with the net result of
pressurising the magnet end and thus preventing media vaporisation in the
magnet area.
Standard versions of the NM pump are fitted with silicon carbide sleeve
bearings with a diamond coating to provide a short term dry-running
capability. Capacity is up to 270m3/h at differential heads up to 150m.
Standard units can operate up to 240°C, and specials are available for
400°C temperature running.