Sealless Magnetic CoupledMultistage Centrifugal Pumps

Type HZM / HZMR / HZMB

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forenvironm

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protection

General

DICKOW-pumps of series HZM are seallessmultistage horizontal centrifugal pumps, drivenby a synchronous permanent magnetic coupling.The static containment shell forms a closedsystem with hermetically sealed liquid end.

Application

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

Max. capacity and differential head:

50 Hz - appr. 500 m3/h and appr. 380 m60 Hz - appr. 500 m3/h and appr. 460 m

(appr. 2200 gpm and 1500 ft)Higher heads are available on request.

The maximum operating temperature is 200 °C.

Hazardous area

Together with the required Ex-drive motors, theHZM-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 (HZMB) the contain-ment shell temperature is limited when usingex-motors. The values are available on request.

Design / Casing

HZM-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.

Containment shell

The containment shell is a pressure vessel toseparate the pumped liquid from the atmosphereonly. The shell is not used as an additionalbearing holder. Therefore, no dynamic stressoccurs.

The standard containment shell is a one piecedeep-draw design without additional welds madeof 2.4610 (Hastelloy C).

The containment shell is bolted to the bearinghousing in a manner that allows removal of thebearing bracket together with the drive rotorwithout draining the pump.

Other available material options are:

- Zirconium oxide (industrial ceramic) without eddy current losses.

- PEEK composite (carbon fibre reinforced Polyetheretherketon) without eddy currentlosses.

- Titanium for high pressure applications.

- Segment containment shell with duplexsegment rings (design SCS) or zirconium oxide tube (design SZCS) for high power and high pressure applications.

Magnet coupling

The single elements of the multipolar magnetcoupling are manufactured of permanent magnetmaterial Samarium Cobalt with unlimited lifetime.The magnets in the driven rotor are completelyencapsulated, not in contact with liquid. Poweris transmitted to the hermetically sealed liquidend by a bank of external magnets. Inner andouter magnet rings are locked together bymagnet forces and work as a synchronouscoupling. The inner magnet ring transmits therequired torque direct to the impeller. Overloadof the magnet coupling and slipping will notcause demagnetization if temperature monitoringis available. The magnet couplings are designedfor electric motors, direct on line starting.

Should a increase of motor power be required,i.e. when installing a larger impeller, the nominalpower of coupling can be increased with addi-tional magnets.

The maximum drive power of HZM / HZMR-pumps is approx. 220 kW @ 2900rpm(350 HP @ 3500 rpm).

Monitoring

Connection for temperature sensor for contain-ment shell surface temperature is available asstandard. Dry running protection, monitoring ofball bearings and pump protection with thepatented "mag-safe" system is recommended.

Containment shell 2.4610

Double sleeve bearings

The pump shaft is carried by wetted sleeve bear-ings. Standard material is pure Silicon Carbidewith DLC coating, providing limited dry-run capa-bility. SiC is highly resistant to corrosion andwear and can be used for all kind of liquids, alsofor solid containing products. The SiC-components are shrinkfitted or elasti-cally beared by tolerance rings and thereforeprotected against shock and thermal stress.

Outer ball bearings

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

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

The drive shaft of HZMR-pumps is carried bygenerously dimensioned oil lubricated antifrictionbearings. The bearings are rated for min. 25000operating hours. The oil bath is protected againstthe atmosphere 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.

Thrust load balancewith double acting balance disk

A partial flow is lead from pump discharge to bal-ance chamber I (between double acting balancedisk and throttle) and pressurizes this chamberwith the discharge pressure.

Balance chamber III (between double actingbalance disk and slide bearing) is pressurizedwith the pressure of the first stage.

In balance chamber II (between the two station-ary SiC thrust bearings) the pressure is variable.The floating shaft determines the pressuredepending on pressure difference betweenchamber I and II and the variable throttle of gapS1 and S2.

Advantages of this thrust balance:

• Internal circulation with rear impeller, that means no more vortex breaker on containment shell bottom is required anymore. (Reduced wear by potential solids.)

Working principle

If the gap S1 is opened by a thrust load in di-rection of containment shell the gap S2 will beclosed and the pressure in balance chamber IIincreases. This pressure acts on the balance diskin the opposite direction and tries to close gap S1 until the thrust load is balanced again.

This balancing system of course also works incase of thrust loads acting in the opposite direc-tion.

A major part of the partial flow going into balancechamber I is also used for the new internal circu-lation taking care of the eddy current losses. This partial flow is lead through the shaft to the containment shell and via rear impeller and gapbetween rotor and containment shell back to thedischarge side.

• No special thrust load measures on impellers required.

• Only one external pipe from balance chamber III behind the suction impeller.

• The slide bearing in suction casing gets an internal vent and drain bore.

• Repair is possible without special parts.

Internal circulation with rear impellerrear impeller

pressurefrom

discharge

throttle

internalcirculation

discharge casing intermediate flange sleeve bearing

Thrust load balance system

intermediateflange

variable throttle(gap S1 and S2)

throttle

floating shaft

balancechamber III

balancechamber II

circulation tofirst stage

pressurefrom

discharge

throttle

balancechamber I

double actingbalance disk

discharge casing

HZM-Design containment shell protection

internal magnets external magnets

containmentshell

bearing bracket

diffuser

ball bearings, grease lubricated

sleeve bearing,discharge side

discharge casingstage casing

suction casing

sleeve bearing,suction side

closed impeller

Optional designsType HZMR – with oil lubricated bearing bracket

mag

net c

oupl

ing

oil b

ath

bear

ing

brac

ket

Type HZMB – close coupled design

mag

net c

oupl

ing

mot

or

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ern

Issu

e 11

.16

Technical changes reserved. Printed in Germany. 100-11.16 S&W

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

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

Performance range