0262 1762/05 © 2005 Elsevier Ltd. All rights reserved WORLD PUMPS February 200532

Developed by Blackmer Pumps,the Mouvex principle is basedon the operation of an

oscillating eccentric piston thatproduces the pumping performance of arotary positive displacement pump.However, its action is far more

sensitive, making it ideallysuited to applicationswhere shear andpotential leakage are

major issues.

Mouvex principle

The Mouvex principle pump differsfrom other types of positivedisplacement pumps in that it does notagitate the pumped liquid. Rather, theliquid is pumped by the eccentricmovement of the oscillating pistonwithin the pump chamber, this being avery gentle action. The direct-drivedesign of the pump does not requireeither mechanical seals or magnets, soit provides leak-free performance.

The eccentric movement pumpconsists of a cylinder and a pumpingelement mounted on an eccentricshaft. As the eccentric shaft rotates, thepumping element creates chamberswith the cylinder. This has the effect ofincreasing the size of the intake portand drawing fluid into the pumpingchamber. The fluid is transported to thedischarge port where the size of the

pumping chamber decreases. Theaction squeezes the fluid out into thedischarge pipework.

Suitable for throughputs up to 36m3/hand pressures up to 9 bar, BlackmerMouvex C and S Series pumps providea constant product flow that isindependent of both pressure andviscosity. This, together with thepresence of automatic piston/cylinderwear adjustment, ensures full flowefficiency and high levels of productstability at all times. In addition, thedesign ensures that very high levels ofaccuracy can be attained for volumemetering and dosing.

C Series

The Blackmer Mouvex C and S seriespumps, whilst employing the sameoperating principle, have beendeveloped for very different

application areas. In the case of the CSeries, the eccentric shaft is encasedwithin a metal bellows constructedfrom 316 stainless steel (Fig. 1).Available in both 316 stainless steeland ductile iron construction, theATEX compliant C Series conforms tostandard 3A and the hygienicrecommendations required byEHEDG.

Self-priming and capable of dry-running, this type of pump will clearboth the intake and discharge lines of any residual liquid. Lubrication ofall moving parts is provided by the pumped medium. Cleaning isperformed in place simply by flushingout the unit without any require-ment for disassembly. Application areas for this pump typically include chemicals, resins, cosmetics,agrochemicals, petrochemicals, paper-making, personal care products andaggressive foods and beverages.

Leak-free pumping with Mouvex Technology

Throughout all areas of processing, there is a substantial requirement for pumps that arecapable of handling shear sensitive liquids and liquids that can have an adverse affect onmechanical seals. Coupled with this is often the need for such pumps to offer leak-freeperformance. Tony Peters of UK-based AxFlow looks at the ‘Mouvex’ pumping principle.

f e a t u r e l e a k f r e e p u m p s

Figure 1. Theeccentric shaft inthe C Series isencased in metalbellows.

Figure 2. The close tolerances of the C Series give a good priming capability.

WORLD PUMPS February 2005 www.worldpumps.com 33

Two highly contrasting applicationsclearly demonstrate the capability ofthe C Series pump. In a plantproducing automotive paints, a C18iunit has been employed for four yearsby a manufacturer of cationic paste(with pigments) and cationic binder(without pigments). These materialshave a maximum viscosity of 100 cpsand a flowrate of 18 m3/h.

The Mouvex pump is employed intransferring the cationic binder fromholding tanks to the mobile tankersthat deliver the fluid to the car manufacturing plants. However,because the catatonic binder is proneto rapid drying between tankerloadings, employing pumpscontaining dynamic seals is a problem.The seal-free design of the Mouvexpump eliminates this problem andprovides operators with a “clean”solution.

The same C18i design is beingemployed in a food processing plant fordecanting orange concentrate. Here,the concentrate has a viscosity of 3000cps and a requirement to be pumped at3 bar with a flowrate of 3 m3/h. At thislocation, typically reserved for lobepumps or circumferential piston pumps,the customer wanted to optimisedecanting time. At the same time, theend-user wanted to contribute to thesatisfactory execution of the sanitaryprotocol required for the preparation ofits concentrates intended for bottlers.Installed in parallel, the two C18ipumps optimise decanting time as perthe viscosity of the orange concentrate,

this being achieved by controlling therotational speed of the two pumps.

The high priming capacity of the pumpensures good decanting regularity andenables the pump to run in a dry

condition for several minutes whichis of importance at the end of the decanting cycle. Theexcellent volumetric accuracy ofthe pump makes it possible at

the moment of decanting tosimultaneously supply a filtering

battery before supplying a storage tankpreceding final preparation. It is theclose tolerance characteristics of thepump design that provide good primingcapability (Fig. 2).

S Series

In contrast, the S Series pump is amore compact and lightweight unit,having the transmission mechanismprotected by a high-resistanceelastomer sleeve that is both odourlessand taste-free (Fig. 3). This enablesthe pump to meet the requirements forFDA certification (S4C and S6C).Very much intended for food, drinkand personal products processingduties, S Series Mouvex pumps havebeen designed for CIP and SIPcleaning. The slow movement of theoscillating piston provides accuratevolumetric metering and enablesprecise dosing and mixing of high andlow viscosity liquids.

In the recovery of coffee flushing,where the pumped product is coffeeextract, two Mouvex S4C units havebeen used re-expediting the mixture ofa varying thickness to a re-treatmenttank (Fig. 4). From this tank, thecoffee extract is sent to a purificationplant. In this particular manufacturingplant, the dual pump installation hasto operate in three eight-hour shifts,so the highest degree of reliability isrequired. With its seal-free design, theMouvex pump provides this reliabilityand reduces the need for maintenance,with the pumps being opened forinspection only once a year.

The S Series pump is also well provenacross a wide range of products in the

dairy industries. In one particularinstallation involving supplyingconcentrated milk to a spraying tower,the main operating requirementsinvolved were a constant flow of 8 m3/hand a pressure of 7 bar. Volumetricefficiency and accuracy were required, asthe response time after any adjustmenthad to be as short as possible, with nounwanted fluctuations. The S6C unitsupplied was able to demonstrate itscapability to meet these operatingtargets on a three eight-hour shiftprogramme and comply with a CIPregime of 30 m3/h four times a week.

Being ATEX, EHEDG and FDAcompliant, applications for Black-mer Mouvex pumps are many. In othertypes of positive displacement pumps,the shear sensitive productsencountered in manufacturing presentconsiderable problems for mechanicalseals, whilst aggressive liquids con-tribute to premature wear of seals.This is not the case with the Mouvexprinciple. None of the wettedpumping elements rotate, therebycreating the gentle, low shear forcesthat many processes require. ■

CONTACTTony PetersAxflow Ltd, Orion Park, Northfield Avenue, Ealing, London W13 9SJTel: 020 8579 2111Email: info@axflow.co.ukInternet: www.axflow.co.uk

f e a t u r e l e a k f r e e p u m p s

Figure 4. Two Mouvex S4C units have been used re-expediting themixture of a varying thickness to a re-treatment tank.

Tony Peters has been managingdirector of AxFlow Limited since 2001 and has over 25years’ experience in the pumpindustry.

Figure 3. The S Seriesis both compact and

lightweight.