| HAMILTON City Council produces and delivers A-grade water to its 130,000 residents and surrounding districts – which the plant operators are justifiably proud of. The Council is also proud that it strives to optimise the process for the effective and efficient use of ratepayer money. Hamilton’s drinking water is sourced from the Waikato River and goes through a typical treatment process. After the water is initially screened to remove large debris it enters a coagulation process where raw water settles in tanks allowing unwanted materials to be removed. Polymer is added to the raw water to aid this process at flow rates of 150-200L/hr, 24 hours a day, 365 days of the year. The plant previously had four diaphragm pumps that were more than 40 years old for this service. While these pumps were almost antique items, there was also a string of drawbacks. Maintenance required a skilled fitter-tuner which was timely and costly, and because spare parts were difficult to source, the Council had resorted to having replacement diaphragms made in-house. The pumps were fitted with several ancillary items that also needed servicing, along with more complex integration of stroke and speed management into the PLC. Sven Ericksen the council’s team leader asset maintenance, was looking for a logical replacement pump that met the needs of product delivery in the most cost effective manner, while simplifying asset complexity and ensuring maximum reliability. The Watson-Marlow 620DuN/RE peristaltic pump was put to the test for a month, and met all of their expectations. “There are numerous advantages of the Watson-Marlow pump” states Sven. “Seeing the rotating pumphead enables the operator to acknowledge that the pump is delivering the polymer at about the right flow-rate; the pump was seamless to integrate into our system; and, best of all, you just need two index fingers and a thumb to change out the tube, saving us time and money.” On the subject of the tube, during the trial back in October the Watson-Marlow 620DuN/RE was fitted with a 12mm Marprene Loadsure tubing element with cam and groove fittings that lock into the pumphead. This same tube is still occluding in the pump, having given seven-plus months of maintenance-free service. The peristaltic motion is also key to ensuring that the polymer is not altered during the pumping process. Polyelectolyte is a viscous long-chain molecule that can be prone to crystallization and/or gelling. Due to its composition, shear can easily break the molecular chains. The Watson-Marlow pump has an open flow path with no intrusions from check valves or other items which makes the design inherently capable of moving shear-sensitive, viscous or particulate fluids with no damage. Also because the pump is self-priming and can run dry, there is no concern for crystallization of the polymer. Hamilton City Council are currently in the process of replacing all of their polymer diaphragm pumps with Watson-Marlow pumps and are looking to optimise other areas of the plant with peristaltic technology. • Email: Olivia Kardos: Olivia.kardos@wmbpumps.co.nz |
|
