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HZM Series

  • Overview
  • Features & Benefits
  • Specifications
  • Other Info

Overview

Dickow’s HZM Series are multistage horizontal centrifugal pumps, driven by a synchronous permanent magnetic coupling between bearings ring sections with closed impeller, end suction and top discharge flange.  HZMB models are close-coupled.  A static containment shell forms a closed system replacing double acting mechanical seals, along with external fluid reservoirs and the necessary control equipment.

HZM pumps are designed to handle toxic, explosive and polluting liquids, particularly in applications where the required differential heads are above the application range of single stage volute casing pumps.  The HZM series have a maximum flow rate of 500 m³/hr and maximum differential head to 380 m.  The maximum operating temperature is 200°C.

The single elements of the multipolar magnet coupling are manufactured of Cobalt-Samarium with unlimited lifetime.  The magnets in the driven rotor are completely encapsulated and not in contact with liquid.  Power is transmitted to the hermetically sealed liquid end by a bank of external magnets.  Inner and outer magnet rings are locked together by magnet forces and work as a synchronous coupling.

The inner magnet ring transmits the required torque direct to the impeller.  Overload of the magnet coupling and slipping will not cause demagnetization if temperature monitoring is available.  Should an increase of motor power be required, i.e. when installing a larger impeller, the nominal power of coupling can be increased with additional magnets. The maximum drive power of HZM pumps is approx. 220 kW at 2900 rpm.

The internal clearance between rotor and containment shell is approximately 1.0 mm for standard containment shells. This allows – together with wear-resistant SiC sleeve bearings – handling of solid containing fluids.

The drive shaft of the HZM versions is carried by antifriction bearings, grease filled for lifetime and protected against the atmosphere by a lip seal.  In HZMB versions, the drive rotor is mounted on the motor shaft - additional bearings, elastic coupling and coupling alignment are not required.  The drive shaft of HZMR variants is carried by oil-lubricated antifriction bearings.  The bearings are rated for 25,000 operating hours.  The oil bath is protected against the atmosphere by a contactless labyrinth seal.  Oil level is controlled by constant level oiler.  The oil chamber is sealed from the magnet chamber also by labyrinth seal.

The pump shaft is carried by wetted sleeve bearings of pure Silicon Carbide with a diamond layer, providing limited dry-run capability.  All HZM pumps benefit from a thrust load balance system which keeps the pump shaft in position during start-up and shut-off.

When fitted with suitable Ex-drive motors, the pumps can be applied in hazardous area Group II, Category 2.  The pumps meet the basic safety and health requirements of Explosion-proof Directive 94/9 EC and are suitable for plants with increased safety requirements.

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