An eccentric approach to pumping

The transferring of paints, coatings, varnishes, pigments, binders and resins throws down a challenge to rotary positive displacement pumps, as all these liquids can prove to be problematical

For these types of liquid, leakage can be harmful to the environment and plant operatives; abrasive materials in suspension can cause component wear (particularly on the seals) and varying levels of viscosity can affect flowrates.

And if these factors weren't enough, a gentle pumping action is normally required in order to provide low shear.

Whilst many types of pump can accommodate some of these demands, the challenge for plant managers is to find one that ticks all the boxes.

Blackmer Pumps, with its 'Mouvex' pumping principle, goes a long way to addressing all these demands.

Exclusive to Blackmer Pumps, the Mouvex principle is based on the operation of an oscillating eccentric piston that produces the pumping performance of a rotary positive displacement pump.

However, its action is far more sensitive, making it ideally suited to applications where shear and potential leakage are major issues.

Mouvex principle.

The Mouvex principle pump differs from other types of positive displacement pumps in that it does not agitate the pumped liquid.

Rather, the liquid is pumped by the eccentric movement of the oscillating piston within the pump chamber, this being a very gentle action.

The direct-drive design of the pump does not require either mechanical seals or magnets, so it provides leak-free performance.

The eccentric movement pump consists of a cylinder and a pumping element mounted on an eccentric shaft.

As the eccentric shaft rotates, the pumping element creates chambers with the cylinder.

This has the effect of increasing the size of the intake port and drawing fluid into the pumping chamber.

The fluid is transported to the discharge port where the size of the pumping chamber decreases.

The action squeezes the fluid out into the discharge pipework.

Eccentric disc pumps are capable of handling up to 30,000 cps (15,000 SSU) liquids, throughputs up to 36m3/h and working pressures of up to 9bar, depending on the model.

The speed range is 50-1000rpm, with capacities of 0.6lt/m -718lt/m.

Rated up to 150C, the C-Series has a particle size range of 1-3mm and is effective at handling suspended solids with mild abrasives.

Blackmer Mouvex C pumps and the recently introduced Micro C, provide a constant product flow that is independent of both pressure and viscosity.

This, together with the presence of automatic piston/cylinder wear adjustment, ensures full flow efficiency and high levels of product stability at all times.

In addition, the design ensures that very high levels of accuracy can be attained for volume metering and dosing.

C Series.

The Blackmer Mouvex C and S series pumps, whilst employing the same operating principle, have been developed for very different application areas.

In the case of the C Series, the eccentric shaft is encased within a metal bellows constructed from 316 stainless steel.

ATEX compliant, the C-Series is available in both 316 stainless steel and ductile iron construction.

Self-priming and capable of dry-running, this type of pump will clear both the intake and discharge lines of any residual liquid.

Lubrication of all moving parts is provided by the pumped medium.

Cleaning is performed in place simply by flushing out the unit without any requirement for disassembly.

"The effectiveness of Mouvex C Series pumps is being realised throughout the paints and coatings industries," says AxFlow Blackmer Product Manager Dave Hutton: "For instance, in a factory producing paints, varnishes and lacquers for can and coil coating this pump has proved successful in transferring Tri Propylene Glycol Di Acrylate (TPGDA) from a tank to the pre-disperser.

This very delicate liquid is environmentally hazardous and polymerises easily, so shearing has to be avoided".

The Mouvex principle with its low linear piston speed does not agitate the product and as there is no bushing inside the pump, there is no risk of local shear of the liquid pumped.

As the pump does not contain seals, an additional internal zone where TPGDA could heat up is eliminated as is the possibility of product leakage.

"The same pump types have been well received in plants producing automotive paints," continues Dave Hutton: "Applications include the manufacture of cationic paste (with pigments) and cationic binder (without pigments), these materials having a maximum viscosity of 100cps and a flowrate of 18m3/h.

The Mouvex pump is employed in transferring the cationic binder from holding tanks to the mobile tankers that deliver the fluid to the car manufacturing plants.

However, because the cationic binder is prone to rapid drying between tanker loadings, employing pumps containing dynamic seals is a problem.

The seal-free design of the Mouvex pump eliminates this problem and provides operators with a 'clean' solution".

The Blackmer Mouvex eccentric disc pump range has recently been extended with the introduction of Micro C Series.

A seal-free eccentric disc pump, AxFlow reports that the Micro C is a low maintenance, compact pump offering flow rates from125l/h - 500l/h.

Available in stainless steel and cast iron, all models are ATEX certified and are able to maintain a constant flow rate at a given viscosity throughout their pressure range.

"Developed for the dosing and transportation of both thin liquids and viscous products, the Micro C provides high accuracy at all times due to the full contact and self-adjustment of the piston and cylinder," reports Dave Hutton: "The high suction performance of this pump enables self-priming even under vacuum conditions.

Low maintenance is assured because of the low number of components and its small footprint means that it can be easily integrated into existing plant".

Being ATEX compliant, applications for Blackmer Mouvex pumps are many.

In other types of positive displacement pumps the shear sensitive products encountered in manufacturing present considerable problems for mechanical seals, whilst aggressive liquids contribute to premature wear of seals.

This is not the case with the Mouvex principle.

None of the wetted pumping elements rotate, thereby creating the gentle, low shear forces that many processes require.

Looking at the factors that are fuelling growth in demand, first up is their seal-less construction, which helps to eliminate high value product loss.

Of even greater importance to users is the pump true CIP capability, this being recognised as a significant economic advantage over pumps that require time-consuming disassembly between batches in order for them to be properly cleaned.

The Blackmer Mouvex C-Series pump can be completely drained, flushed and cleaned in place without there being the need for it to be disassembled.

Nor is there any need to remove piping or pump housings, so maintenance time and costs can be reduced.

Back to top