Following the installation of three Bredel 100mm high-pressure hose pumps in a ring main casting system at Caradon Plumbing Solutions, pinholes in the finished product have been virtually eliminated, scrap has been reduced to a minimum, and maintenance has been slashed.
The Bredel pumps replaced one hydraulic ram pump and two rotary lobe pumps which caused scrap problems due to entrained air and pinholes. With the Watson-Marlow Bredel pumps, maintenance is confined to a six-monthly hose change, and problems with entrained air and metallic contaminants entering the slip simply no longer occur.
The pumping system consists of one pump for each main, a control panel, pressure transducers, pulsation dampers, and flow switches for detecting blocked suction or discharge lines. The required pressure between 0 and 10 bar is maintained in the 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 motor continues to run and provide full torque. As soon as draw off points are opened, the pump speeds up to maintain the required pressure. With all discharge points open, the pump accelerates to maximum, slowing down progressively as discharge points are closed.