Water & Wastewater Treatment Magazine
Issue link: https://fhpublishing.uberflip.com/i/741165
10 | NOVEMBER 2016 | WWT | www.wwtonline.co.uk Comment How much will your pump really cost you? But the expectations of some pump users can be unrealistic when it comes to the cost of pump ownership. In many cases they focus too much on initial outlay, opting for the least cost alternative, which is not always actually the best solution for the application. So what is the answer? The BPMA and many of its members are keen to emphasise the importance of lifecycle costing (LCC) as a vital part of any pump purchasing and ownership strategy. Lifecycle costing takes into account many factors, all of which impact on the total cost of owning and operating a pump, which includes much more than just the initial outlay. A pump's lifecycle cost encompasses the total overall costs that accumulate throughout the life of a pump, from installation, energy consumption, operation, maintenance and downtime, right through to the final decommissioning and disposal of the pump. By carrying out an analysis of the costs that are likely to be incurred throughout the operational life of the pump, it is possible to objectively compare all the potential options at the outset. Lifecycle costing can be useful not only for selecting new equipment but also for justifying the upgrade of existing systems. Throughout the lifetime of a pumping system, it is unlikely that the same operating conditions will continue to prevail. Factors such as the addition of new equipment upstream of the pump or changes in production techniques can all cause variations in pump duty away from the pumps 'Best Efficiency Point' (BEP). This is the point where pump capacity and head pressure combine to provide the maximum efficiency performance from the pump. If the pump is incorrectly sized and is operating too far from the BEP, wear and tear can occur which can shorten its operational life. An oversized pump, for example, will not only be inefficient, but will also cost more to maintain because operating too far to the le‰ of its performance curve puts an extra strain on pump bearings and seals. On the other hand, a pump which is undersized for the duty may end up running too quickly, which may potentially ruin the product being pumped and also prematurely wear out parts of the pump. Its efficiency will also be affected, resulting in excessive energy consumption. Although a pump should be sized to an application, achieving this is not always straightforward. Involvement of third parties and the need to meet possible changing future requirements can all affect the sizing of a pump. Over-design on parameters is very commonplace. If every party involved in specifying a pump adds on even a small percentage to their sizing estimate, the end result can be a highly inefficient pump. The extra cost, both in terms of running and maintaining the pump can be very high over the life of the plant. One survey of 4,000 installations showed that water pumps typically operate with a Steve Schofield DiREcTOR aND chiEf ExEcuTiVE BRiTish PuMP MaNufacTuRERs assOciaTiON (BPMa) When it comes to specifying pumping equipment, many companies under pressure to cut costs could actually be making decisions that will cost them more in the long run T he need to cut costs wherever possible is an increasingly familiar requirement for engineers charged with ensuring the continued smooth operation of plant on a limited budget. When it comes to pumping systems, although choosing the lowest cost option may seem like the best short term solution to achieving cost savings, it will almost always result in additional costs being incurred that could have been avoided by spending a little more time and money during the specification and design stage. Pumping systems can account for between 25 and 50% of the total energy consumed by certain industrial processes. Add to this the need for ongoing service, repairs and maintenance throughout a typical service life of 20 years and pumps quickly begin to represent a substantial area of expense. Too many users fail to take account of the full lifecycle costs of a pump