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Life cycle 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 life cycle cost encompasses the total overall costs that accumulate throughout the life of a pump, from installation, energy consumption, operation, maintenance and down time, even environmental and 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 left 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. Also its efficiency will 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 4000 installations showed that water pumps typically operate with a shortfall in efficiency of between 12.5 and 20% because they are incorrectly specified. The situation is worse for pumps that handle more unusual or complex media, such as chemicals or pharmaceuticals.

To help with changes in duty and assist with energy reduction many pump manufacturers are now promoting the use of Variable Speed Driven pump systems, frequency drive being the most prominent system used.

By using VSD’s you in effect combine electrical and mechanical principles.

The addition of the latest controls or ancillary equipment can often help boost efficiency and enable pumps to meet changes in demand at a fraction of the cost of building a new system from scratch. In some cases, simply upgrading a pumping system can result in energy savings of up to 50%.

The importance of good design

Maintenance and energy consumption represent by far the two most significant costs throughout the life of a pump. The answer to minimising these costs lies in ensuring a well-designed pumping system, where the pump is specified as correctly as possible to the demands of the application. The energy consumption and efficiency of a pump is closely linked to the way that a pumping system is designed and operate