Hose pumps reduce scrap in ceramics manufacture

Caradon Plumbing Solutions has virtually eliminated pinholes in its finished products following the installation of three Watson-Marlow Bredel high pressure hose pumps.

Caradon Plumbing Solutions has virtually eliminated pinholes in its finished products following the installation of three Watson-Marlow Bredel high pressure hose pumps.

The three hose pumps have directly replaced a hydraulic ram pump and two rotary lobe pumps and have significantly reduced scrap rates due to entrained air and pinholes.

In addition, Caradon also benefits from significantly lower maintenance costs with the new pumps, as maintenance is now confined to a bi-annual routine hose change.

The Caradon pumping system consists of three integrated ring mains with approximately twenty discharge points, supplying 36 oz/pint clay slip to the casting machine.

Although inter-linked, each ring main can also function separately when required, and each consists of one pump together with control panel, pressure transducers, pulsation dampers and flow switches.

The required pressure of between zero and 10 bar is maintained in the ring main, regardless of the number of open discharge points.

With all points closed and pressure at the required level, pump speed is zero, although the motors continue to run and provide full torque.

Each hose pump is an SP100 (100mm i.d.

hose) fitted with an 18kW vector drive, to provide a flow rate of between zero and 27,000 litre/hour.

As soon as draw off points in the system are opened, the resultant pressure drop is sensed and the pump speeds up to the flow rate required to restore and maintain pressure.

With all discharge points open, the pump accelerates to maximum, slowing down progressively as discharge points are closed.

The pumps support a multi-cast operation for approximately ten hours.

Between castings, the complete system can be switched to recirculation mode.

Valves in the system are continuously monitored and in the event of a valve malfunction, the system is automatically shut down.

Other safety devices are incorporated to stop the pump in the event of hose failure and blocked suction or discharge.

Watson-Marlow Bredel pumps are extensively used for handling slip in the ceramics industry.

The low shear, low speed pumping action without vanes, lobes or stators ensures that slip is handled with minimal turbulence so that the liquid/solids ratio remaining constant.

With the slip enclosed within the hose throughout pumping, the risk of ingress of air or contaminants via the pump is for practical purposes, eliminated.

In addition with no glands or seals in the pump to break down, metallic contamination from the pump is impossible.

The Watson-Marlow Bredel range includes units capable of pumping micro litres up to 80,000 litres per hour, at pressures up to 16 bar.

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