Dickow specializes in supplying centrifugal pumps with a seal less magnetic coupling. Our model NMWR/NMWB are specifically designed for high temperature heat transfer fluids (hot oil) up to 750 F without any water cooling. The series NMWR/NMWB are sealless with no shaft duct to the atmosphere. The containment shell forms a closed system with a hermetically sealed liquid end replacing double acting mechanical seals with external fluid reservoirs and necessary control equipment. Additionally, the containment shell is not used as an additional bearing holder meaning no dynamic stress occurs.
As in all Dickow sealless pumps the magnets are permanent rare-earth Samarium Cobalt with unlimited life. The driven rotor is completely encapsulated as to not come into contact the pumped liquid. Power is transmitted through the containment shell by a bank of external magnets. The inner and outer magnets are locked together by magnetic forces and operate as a synchronous coupling. The inner magnet transmits the power to the impeller at the same speed as the motor.
The bearing housing has been designed as a cooling devise with cast on fins that dissipate heat to the atmosphere. This keeps the temperature inside the containment shell below the system temperature in the volute casing.
The pump shaft is carried in the wetted end by pure Silicon Carbide (SiC) with a diamond layer that allows for limited dry running. The SiC components are elastically fitted in their holders which eliminate any concern of thermal shock and stress at high pumping temperatures. SiC is highly resistant to wear and corrosion.
The NMWR is long coupled. The drive shaft is carried in generously dimensioned oil lubricated antifriction bearings that are rated for 25,000 hours of operation. The oil bath is protected against the atmosphere and separated from the magnetic coupling by two labyrinth seals. The level of the oil is controlled by a constant level oiler and a site glass.
The NMWB is closed coupled eliminating the requirement of the oil bath and bearings. Additionally, the closed coupling shaft misalignment issues. The maximum capacity of these pumps is 4,000 gallons per minute with differential head 500 feet.