By Mark Redit
For many years, Life Cycle Cost calculation has been used to evaluate selected pumps to determine which provides the user with the most cost effective solutions. In recent years, this type of calculation has been further developed, but in most cases end users continue to use the LCC calculation in its most basic form.
This basic calculation, which includes initial cost, new energy and maintenance costs, when used for sewage application, drives manufacturers, equipment suppliers and specifiers towards selecting equipment that does not give the best value for the customer. In many cases, the calculation steers the end users towards choosing equipment that has high efficiency when new, but results in significant on-site support costs to fix blockages and very high efficiency losses caused by wear.
It also penalises many design features that have been proved to significantly reduce operator support costs and efficiency losses as a result of wear, such as:
• Designs that have good solids handling capabilities and, therefore, less on-site support costs are penalised when compared to high efficiency designs that block on a regular basis.
• Increasing the number of impeller vanes improves efficiency in many cases; however this greatly reduces solids handling capability.
• Designs with adjustment features that increase efficiency on site without replacing parts help lower energy costs over the life of the unit. These designs are penalised against low-cost simple designs without this feature.