Sealless Magnetic CoupledMultistage Centrifugal Pumps

with Priming StageType HZSM / HZSMB / HZSMR /

HZSMA / HZSMAR

ourcontribu

tion

forenvironm

ental

protection

Containment shell

The containment shell is designed as a pressuri-zed vessel to separate the pumpage from theatmosphere. The containment shell is not usedas an additional bearing holder. No dynamicstress occurs.

The containment shell is bolted to the bearinghousing in a manner that allows removal of thebearing bracket (HZSM-pumps) respectively ofthe drive motor (HZSMB-pumps) together withthe drive rotor without draining the pump.

Priming stage

The side channel stage is capable to evacuatethe suction line and therefore, to selfprime if initi-ally filled with operating liquid. In the primingphase the side channel pump works as a positivedisplacement pump. The displacement effect iscreated by a rotating liquid ring which enters andexits the side channel in a piston fashion by eachrotation. This is generated by an interrupter in theside channel which separates suction and pres-sure area. The piston effect conveys the gasfrom suction to discharge side. The priming stageworks automatically, no auxiliary vent equipmentis required.

When pumping LPG, attention has to be paid togas entrainment by vapor bubbles. In practice,these pumps can pump this liquid-gas-mixtureswithout auxiliary device. Due to the increasedpressure in the side channel stage, the gas bub-bles turn into liquid phase again.

Magnetic coupling

The single elements of the multipolar magneticcoupling are manufactured of permanent magnetmaterial "Cobalt Samarium" with unlimited life-time. The magnets in the driven rotor are com-pletely encapsulated, not in contact with liquid.Power is transmitted to the hermetically sealedliquid end by a bank of external magnets. Innerand outer magnet rings are locked together bymagnetic forces and work as a synchronouscoupling. The inner magnet ring transmits therequired torque direct to the impeller. Overload ofthe magnetic coupling and slipping will not causedemagnetization if temperature monitoring isavailable. The magnetic drives are designed forelectric motors, direct on line starting. Should asubsequent increase of motor power be required,i.e. when installing larger impellers, the nominalpower of coupling can be increased with additio-nal magnets.

General

DICKOW-pumps of series HZSM are seallessmultistage horizontal centrifugal pumps, drivenby a synchronous permanent magnetic coupling.The static containment shell forms a closedsystem with hermetically sealed liquid end. Theintegrated side channel stage allows the handlingof entrained gas and operation under suction liftconditions.

Application

Magnetic driven HZSM-pumps are designed toimprove plant and personnel safety, especiallywhen handling toxic, explosive or other dange-rous liquids which react on contact with theatmosphere. For all these services the contain-ment shell replaces the double acting mechanicalseal with external fluid reservoirs and the neces-sary control equipment. HZSM-pumps thereforeoffer exceptional benefits to the chemical, petro-chemical and allied industries, and protect theenvironment.

The HZSM-type is used in tank farms, for offloa-ding rail cars and trucks, filling of storage tanksand other applications where priming of emptysuction pipes is required.

Considering low NPSH-values, gas handlingcapability and sealless design, the HZSMA-typeoffers special benefits to liquified gas applica-tions. Typical application is filling of LPG-trucksand rail cars in refineries.

The maximum operating temperature is 180°C.

Hazardous area

Together with the required Ex-drive motors, theHZSM-pumps can be applied in hazardous areaGroup II, Category 2. The pumps meet the basicsafety and health requirements of Explosion-proof Directive 94/9 EC and are suitable forplants with increased safety requirement.

For close coupled pumps (HZSMB) the contain-ment shell temperature is limited when usingex-motors. The values are available on request.

Design / Casing

HZSM-pumps are multistage between bearingsring section pumps with closed impeller, endsuction and top discharge flange. Suction anddischarge casing are provided with sturdy feetfor mounting on base plate.

The pump flanges of HZSM-pumps are providedprincipally in vertical top position to grant a cer-tain quantity of liquid in the pump which is neces-sary for priming empty suction pipes and liftingpumping liquid from underground storage facili-ties. For obtaining low NPSH-value, the suctioncasing is designed in volute shape.

The HZSMA-pumps - for applications with floo-ded suction conditions - are provided with suctioncasings of end suction design to obtain furtherreduction of NPSH-values.

magnetic field

drive rotor

drive magnetscontainment shell

driven rotor

adhesive

adhesive

Double sleeve bearings

The pump shaft is carried by wetted sleevebearings. Standard material is pure SiliconCarbide with diamond layer, providing limited dry-run capability. SiC is highly resistant to corrosionand wear and can be used for all kind of liquids.The SiC-components are shrinkfitted or elastical-ly beared by tolerance rings and therefore pro-tected against shock and thermal stress.

Internal cooling flow

When the pump is in operation, eddy currentsare developed inside the metallic containmentshells and converted into heat in the magnetarea.

In order to avoid inadmissible temperature rise ofthe pumped fluid, this heat is dissipated throughan internal cooling flow.

Outer ball bearings

The drive shaft of the HZSM-pumps is carried bygenerously dimensioned antifriction bearings,grease filled for lifetime and protected against theatmosphere by a lip seal.

The drive rotor of HZSMB-pumps is mounted onthe motor shaft. That means, additional bearings,elastic coupling and coupling alignment are notrequired.

The drive shaft of HZSMR-pumps is carried bygenerously dimensioned oil lubricated antifrictionbearings. The bearings are rated for 25000 ope-rating hours. The oil bath is protected against theatmosphere by a contactless labyrinth seal.

Oil level is controlled by constant level oiler. Theoil chamber is sealed from the magnet chamberalso by labyrinth seal.

Impellers, NPSH-values

When operating hermetically sealed pumps, cavi-tation must be avoided by all means. This appliesespecially for handling hydrocarbons, condensa-tes and other low boiling liquids.

For lowest NPSH-values, the impeller of the firststage is designed as a suction impeller withenlarged eye.

Balanced thrust loads

The thrust loads of the closed impellers arebalanced by throttle gap and relief holes. Thebalancing of residual loads is effected by thebalancing disc on pressure side.

The front side of the balancing disc is pressuri-zed by the pump pressure p1.

The rear disc side is connected with the pressureside of the first pump stage via an external pipe.According to the rotor position and the adjustinggap S, a counter force is created by the differen-tial pressure between front and rear side of thebalancing disc. This counter force acts againstthe residual load towards the containment shellsuch that no thrust loads occur. No thrustbearings are required. The start-up rings keepthe pump shaft in position during start-up andshut-off.

Monitoring

Connection for temperature detection element forcontainment shell surface temperature is availa-ble as standard. Dry running protection andmonitoring of ball bearings and containment shelltemperature with the patented "mag-safe" systemis highly recommended.

p2 < p1

stationary

balancing disc, rotatingand floating with rotor

circulation channel

intermediate flangecontainmentshell

HZSM-Design

ball bearings,grease lubricated

bearing bracket

containment shell

external magnets

internal magnets

balance line

stage casing

suction casing(top suction)

closed impeller

discharge casing thrust loadbalance disc

sleeve bearing,suction side

priming stage side channel impeller

sleeve bearing,discharge side

Type HZSMR – top suction with oil lubricated bearing bracket

Optional designs – HZSM, self-priming

Type HZSMB – top suction, close coupled execution

top suction magnetic coupling motor adapter

self-priming impeller motor

top suction magnetic coupling bearing bracket

self-priming impeller oil bath

Type HZSMAR – end suction with oil lubricated bearing bracket

Optional designs – HZSMA, for handling of liquified gases

Type HZSMA – end suction with grease lubricated bearing bracket

end suction magnetic coupling bearing bracket

gas handling impeller

end suction magnetic coupling bearing bracket

gas handling impeller oil bath

Issu

e 08

.12

Technical changes reserved. Printed in Germany. 080-09.12 S&W

DICKOW PUMPEN GmbH & Co.KGPostfach 125484465 Waldkraiburg · GermanyTel. ++ 49 86 38 6 02 0Fax ++ 49 86 38 6 02 200 + 6 02 201info@dickow.de / export@dickow.dewww.dickow.de

Performance range

Performance curves for the individual pump sizes,also for 1750 / 3500 rpm, with NPSH-valuesand power consumption, are available onrequest.