Transferring media with a high viscosity can be problematical for some types of centrifugal pumps and where the problems of shear have also to be taken into account. Selecting an appropriate pump type needs careful consideration.
Waukesha pumps excel in hygienic cream production
For one leading UK manufacturer of medical creams and gels, the difficulties encountered in pumping products in the final stages of production, where viscosity has increased substantially, has been overcome by the introduction of AxFlow's Waukesha Universal II pumps. In addition to relieving this particular difficulty and satisfying the need for a gentle pumping action, the pumps have substantially reduced cleaning down procedures, resulting in a reduction of materials used.
Brendan Orange, AxFlow sales engineer, takes up the theme. "We have a customer who was experiencing problems with the increase in viscosity of its creams during production. The change in viscosity meant that the low shear pumps used at the early stage of production could not move the product at a rate that was required for a subsequent stage. At this stage of the production cycle, the cream had risen to 6,000cP and the flow rate required was 8m³hr.
The answer that we came up with was a Waukesha Universal II with fixed speed for inverter use mounted on a mobile skid, so that it could be moved from one processing tank to the next as and when required. This also meant that the pump could be rapidly cleaned between operations."
Elsewhere in the plant, the manufacturer was also encountering difficulties when pumping hygienic creams for moisturisers and medical products from storage boxes to hoppers on the filling lines. In this production facility, the creams are batch manufactured in quantities of 1000kg and then stored in boxes for up to six weeks, depending on demand. In terms of viscosity, these products required a pump that could handle up to 240,000cP at rest, but accounting for the product to shear down during operation and operate at between 15 and 40kg/min.
Once again, Brendan Orange recommended the Waukesha Universal II installed on a mobile skid enabling it to be moved from one production line to the next with the minimum of work and also to ease CIP cleaning.
"Cleaning the pump out between batches was a major concern," continues Brendan. "The cleaning regime involves water flush, a caustic wash, water flush, acid wash and a purified flush. Because of the design of the front face of the Waukesha pump, cleaning is a far quicker cycle taking around 45 minutes, compared to the previous pump type which could take up to 120 minutes. Our customer has also seen a reduction in the consumption of detergents, power and water disposal."