04A DW Product Training

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DW Rotary lobe pump

By Product Manager Jesper Holst Rasmussen

Product training


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Definition and classification of pumps

Vane Ecentric casing

Vane screw Screw spindle

Impeller Peristaltic (hose)Ecentric

Rotary LobeGear

Rotating pistonScrew spindle

PumpsPositveDispla-

cement

Reciprocal Piston

Diaphragm

RotarySingleRotor

Multi

Rotor

The most common APV pumps are in bold type in the two tables.

DW PD Pumps


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The DW range Rotary LobePumps for the 21st century

A development from the first RotaryLobe Pump launched back in 1932

DW PD Pumps


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Front cover

Shaft, main

Shaft, auxiliary

Gears

Brearing, font Bearing, rear

Rotorcase

Profiled front covergasket

DW - Construction

Rotor

Rotor screw

Clamp ring

Feet


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Rotors

Feet

Inlet Outlet

Front view

Chassis Machined in one fixing

Small tolerances

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Exploded view


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Exploded view


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Expanding cavities are formed at the inlet drawingthe liquid into the rotors.

Meshing of the rotors forces the fluid out of thepumping chamber.

DW - Construction

Principles of operation


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Internal leakage is fluid that travels from the high pressure side to the lowpressure side of the pump.

Internal leakage is present because of the slip paths between stationary androtary parts in the product area.

hVol = Volumetric efficiency = (theoretical displacement - slip)

theoretical displacement

LeakageLeakage

Leakage

FlowFlow

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Slip Internal leakage


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Efficiency of the pump Slip

Slip increasesproportionallywith pressure

Slip increaseswith the cubeof tolerance

Slip decreaseswith increasingproduct viscosity

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Rotor types

Tri-lobeCommonly useddesign, used invarious applications

Bi-lobe (DW-pump)Used for fluids wherelarge particles mightoccur.The volumetric efficiencydepends on the angle of

the rotor tips

Multi-lobe (R-pump)Used where largeinlets are required orsmooth flow

Bow-tie rotorGood volumetric efficiencyDisadvantage, localcavitation at high speed

Rotary piston (DW-pump)High volumetric efficiencyDisadvantage, expensiveproduction costs due to smallmanufacturing tolerances

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Pulsation Characteristics

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Local cavitation

Trilobe rotors Rotary piston

rotors

Consequence of cavitation

noise

less output

damage to the fluid

vibrations

Cavitation can beminimised by

reducing the internalfluid velocity

optimising the rotor

shape

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Occur when the rotorsmove apart. This change inspeed and volume pulls themedia apart.


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Pulse-free performance

Patented design of rotor tips andgrooves. DW pump runs without pulsation'sand internal cavitation

The patented grove design insures a steady,pulsation free filling and discharge of theproduct.

The patented rotor design allows for higherrotation speed and still maintain a gentle

product treatment.

The pulsation free operation extend thelifetime of valves, instruments etc.significantly.

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Pulsation

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Comparison of measurements on bi-lobe and piston rotors

Measurements at the pump outlet

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Versions available: Multi-duty 110C

High efficiency 110C

High temperature 180C

Super tight (NGA only)

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Rotor Types

Rotary Piston

Pulsation free flow, dueto patented design

Low NPSH valuerequired

No rotor timing

Bi-Lobe

Low internal cavitation

High pressure operation

Lower cost

Rotor material

Stainless steel AISI 316L

NGA (Non-galling Alloy)


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See Operating manual - section 6.6

All rotor types are available in NGA

Rotor type Strength WeaknessMultiDuty 110oC Rapid product temperature

changes up to 80C Relatively high efficiency

High temperature180oC

Tolerances allowtemperature shock changesup to 180oC

Low efficiency due to largetolerances

High Efficiency110oC

High efficiency due to smalltolerances

Can not withstand large shocktemperature changes (ex.

CIP)Super Tight(NGA)

High efficiency also for lowviscosity fluids

Expensive Non Galling Alloysnecessary (75% Ni)

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Rotor Types


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Non Galling Alloy (NGA)

NGA rotors are used where a high efficiency or minimum of slip is required.

Typically where the pump is used for dosing or low viscosity applications.

NGA is a soft stainless steel which do not gall (damage) the surface likeconventional stainless steel.

NGA rotors can have smaller clearance than High efficiency rotors.

NGA rotors can touch the pump house or front without damaging (Galling)the house or the rotors.

NGA rotors have Higher efficiency due to reduced slip.

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NPSHrequired

The NPSHreq. is significantly lowerfor DW pumps compared tocompetitor products.

Since the inlet is behind the rotors

The fluid easily flows into the pump

Inlet volume is increased

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NPSHrequired

Is describing the necessary inlet pressure to avoid cavitation.

Varies from pump to pump.

Depends on rotor width, inlet port diameter, rotational speed, and the fluid viscosity,temperature and vapour pressure.

NPSH required for positive displacement pumps is defined as a 5% reduction inflow at constant rotational speed, viscosity and differential pressure.

Flow rate

Inlet pressure

NPSHR

Norm. flowrate

Flowrate 5%reduction

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Cavitation

Is evaporation of the fluid inside the pump.

Occurs when the pressure in the pump falls below the vapour pressure of the fluid.

Results in: decreased volumetric efficiency

noise

vibrations

damage to the pump, the fluid, and the system.

Cavitation is avoided by keeping the inlet pressure at the pump above the necessarypressure to avoid cavitation, ie. NPSH available > NPSH required.

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EHEDG: European Hygienic Engineering & Design Group

Hygienic pump design = compliance with EHEDG

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EHEDG


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Pumps are classify based on the gear size DW1 - DW7 Dimensioned based on deflection of the shaft

31 models in the pump range

Flow

[l/min]

Pressure

[bar]

n

[rpm]

Weight

[kg]

Dimensions

[mm]

DW1/ 003/ 7.5 40 7.5 1400 18.5 260x218

DW7/420/30 2200 30 600 700 1016x627

DW7/1016/7 5800 7 600 800 1119x627

DW Product range

Classification


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DW Product range


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DW 7/1016/07 rotary lobe pump with 8 inlet

DW Product range

A broad range


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Standard pump

DW pump is equipped with:

Single mechanical shaft seals Sic/Carbon

EPDM O-rings Fittings? Rotor multi duty (lobe or piston) Motor?

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Options

The following standard options are available in the DW range:

Bareshaft pump

Pump with constant speed geared motor, suitable for inverter drive use. Up to 37 kW these areavailable with stainless steel motor shroud.

Pump with geared motor with constant or manually variable speed. Pump base plate and coupling guard in stainless steel.

Lobe rotors suitable for max. 110C or max.180C product temperature, in stainless steel 316L orNon Galling Alloy (NGA).

Piston rotors suitable for max. 110C product temperature, in stainless steel 316L or NGA.

Elastomers in EPDM, FPM (Viton) or ISOLASTTM.

Single mechanical shaft seal in SiC/Carbon or SiC/SiC, flushed or non-flushed.

Double mechanical shaft seal in SiC/Carbon or SiC/SiC . Single EPDM lip seal for DW1-5.

Triple PTFE lip seal (confectionary) for DW1-5.

Packed gland with sealing thread in PTFE impregnation, for DW1-5.

Horizontal or vertical suction and discharge ports.

Rectangular inlet.

Cooling/heating jacket on rotor case and front cover.

Pressure relief valves on DW1-5.

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Single mechanical shaft seals

Single mechanical

Carbon / silicon carbide seal: Clean fluids (not sticky or abrasive)

Silicon carbide / silicon carbide seal: Abrasive, tacky (sticky) products

Single flushed mechanical - low PressureFlush

Crystallising media in contact with the atmosphere Liquids close to their boiling pointWhere dry running of the seal faces may occur

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Product wetted end

Same as Single Flushed seal+

High temperature products

Vacuum extraction

Solidifying products

Aseptic processes

Hazardous or toxic products

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Double mechanical shaft seals

High or low Pressure flush


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The packed gland:Max. 10 BarAbrasive slurries, viscous and aggressive productsNot hygienic, not suitable for CIP.

The confectionery seal (Triple lip seal):Max. 6 BarChocolate.Not suitable for CIP

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Alternative shaft seals


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Elastomer

EPDMUsed in standard applications, not oil resistant

Flourocarbon (Viton)Good heat resistance feasibility's, used in applications containing oil

Perfluoroelastomers (Isolast)Used in chemical applications, resistant to most chemicals, low frictiongood heat resistance, excellent mechanical qualities.

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Enlarged rectangular port for high-viscosity products.Inlet area is increased by 100 - 200% dependent on pump size.

Rectangular inlet

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Rectangular inlet

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New construction will belaunched in August


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Constant temperature of the liquid in a pump.

The thermal jacket facilitate the heating or cooling of the pump chamber prior

to product entry.

Thermal Jacket

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Thermal Jacket

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New construction will belaunched in August


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Standard Relief Valve

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Tube version TYPE 1

Folded version TYPE 2

Baseplate

Hygienic Aspects

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DW pump mounted on the hygienic tubular support with shroud.

The shroud protects gear and motor during washing of the eqipment.

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Motor shroud


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Pump drive (motor)

Constant speed drive = Nordgear

Manual variable speed drive = SEW (On request)

Speed control via Frequency converter = Nordgear

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Wide range - 31 models

Patented Rotor design

All external surfaces are in Stainless steel

No painted surfaces

Easy to service

Inlet / outlet port orientation easy to change on site

Self draining when vertically ported

Low NPSH required EHEDG certified / FDA approved materials / 3A certified

EHEDG certified integral pressure relief valve

DW Customer benefits


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Dairy

DW - Applications

To & From Pasturisers

Tank Transfer Duties

To & From Heat exchangers

Tanker Pumps

Finished Products

Products

Yoghurt Products

Concentrates Cream

Cheese Products

Butter

Dairy spreads

Dairy based drinks

Ice cream


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Food

DW - Applications

To & From Pasturisers

To & From Heat Exchangers

Bulk Transfer

Tanker loading/unloading

Transfer from cookers and

Mixers to filling lines

Evaporation

Finished Products

Products

Meat products

Egg Products

Bakeries

Jams &

Preservatives

Baby Food

Sauces & Soups

Permeat

Condensed Milk Confectionery

Sugars & Chocolate

Gelantine

Glucose & Syrups


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Brewery and soft drinks

DW - Applications

Bulk Storage

Separator Feed

Pasturiser Feed

Dosing

Tanker Loading/Unloading

Filling Lines

General transfer

Products

Beer

Yeast Trub

Spirits

Carbonated Drinks

Cider

Fruit Juice &

Concentrates


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Pharmaceutical and toiletries

DW - Applications

Bulk Transfer

Dosing

Process Tank Supply

Filling

Products

Shampoos

Liquid soap

Hand Cream &

Lotions

Make up

Moisturizer

Toothpaste

Insulin

Water for injection Antibiotics

Ointments


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Chemical

DW - Applications

General Transfer

Tanker Loading/ Unloading

Dosing

Bulk Storage

Products

Acids

Solvents

Detergents

Emulsions

Photographic film

coating

Paint, Ink & Resin

Oils Adhesives


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General industry

DW - Applications

Bulk Transfer

Dosing

Tanker Loading/Unloading

General Transfer

Products

Clay Coating

Starch

Latex

Pigments

Dyes

Resins & Pastes

Vegetable/Mineral

Oils Paints

Documents

04A DW Product Training