Pump maintenance: keeping it pumping
Maintaining pumps in top condition is a vital consideration in the totex equation for pumping assets, and water utilities can benefit in this area from the help on offer from the supply chain
When it comes to calculating the cost of a pump, maintenance costs are often the hardest to pin down and predict. Unlike upfront capital expenditure, which is usually front of mind for procurement teams, or energy use, which dominates the thinking when it comes to operating expenditure, the cost of maintaining pumps is frequently underestimated and the subject of dubious assumptions. Not only are maintenance costs dependent upon system reliability, design and operating conditions, but they can also vary widely according to how effective the asset owner is at monitoring its own pumps and nipping any problems in the bud.
Water utilities, which are obliged by their regulators to consider the impact of their decisions on total expenditure, can find that wastewater pumps in particular can rack up spiralling maintenance costs if they are poorly specified, face unexpectedly challenging effluents or suffer from frequent blockages. In such cases, the way the maintenance regime is arranged, and the knowledge and ability of the operations team to respond to issues, can be as important as choosing the right pump in the first place.
However, the good news is that there is much that operators can do to raise their game in this area, and even more that can be achieved if they are willing to engage expertise and services from pump manufacturers and the supply chain.
So what are the keys to improvement?
With a host of technologies now available for monitoring the performance of a pump and for accessing and analysing the performance data remotely (including the Internet of Things and the Cloud), there is no reason why maintenance must take the form of formulaic, regular, scheduled visits. Instead, condition-based maintenance – where effort is focused on the assets most likely to need attention based on performance data – is considered by many to be best practice. Anglian Water is a leading example of a utility that has concentrated on monitoring the performance of its pumps through its Energy Efficiency Management System, which identifies where a piece of equipment is performing inefficiently and can help to focus operator attention.
Manufacturers are well positioned to help with performance monitoring and optimal maintenance. For example, Grundfos offers iSolutions, a service to optimise the efficiency of the entire pumping system, and service agreements where regular reports are given on pump performance and visiting maintenance engineers ensure pumps continue to run at the optimal place on the energy curve.
Given that even the best-performing pumps will occasionally need to be repaired and eventually replaced, it makes sense to design pumping installations so there is ease of access for personnel carrying out this work. Preferably, the pumps should not have to be physically removed from their location, which is what maintenance-in-place design is all about.
“When there is conclusive proof that, for example, one design of pump may require just one hour of maintenance, compared with say, four hours’ work on a more cumbersome design, there are massive savings to made – savings that you’d think would put a very big tick in any water company’s asset delivery box,” says David Brown, UK managing director at pump manufacturer Börger.
“Maintenance-in-place doesn’t require special tools, and can mean the difference between just one person carrying out the work, or two. Likewise, with a bigger, more difficult pump to fix, it could mean having to send out just one van, rather than two. These savings are so substantial that they should not be ignored,” adds Brown.
It might seem obvious, but the best way to ensure that potential problems are spotted early and do not develop into a costly maintenance headache is for operators to be fully trained in the workings of the pumping systems deployed; while maintenance work itself can be outsourced, there is no substitute for a knowledgeable and skilled operator. Many pump suppliers offer operation and maintenance training: Sulzer, for example, offers courses that can be delivered at its manufacturing facilities or on the customer’s site.
“Training from Sulzer specialists delivers more than the skills to dismantle, repair and rebuild a pump,” says the company. “With a foundation in the principles of pump operation and related systems, trained staff can quickly and accurately identify poor installations and take appropriate corrective action to avoid premature failures.”
When running a large number of assets of a similar type, it is important to analyse the specific cause of individual failures so that operators can identify any weak points that might need closer monitoring across the asset base.
For example, 98 per cent of mechanical seals on pumps fail before their optimum design life, and seal failure is the leading cause of pump and mixer downtime, according to Flowserve SIHI. The manufacturer has developed a simple web-based tool – the Flowserve Seal Failure Analysis App – which enables users to identify visually and diagnose the root cause of seal failure.
“This new way of supporting our customers, on a 24/7/365 basis, provides engineers with more than 100 years of acquired knowledge at their fingertips,” explains Shaun Hampson, Flowserve SIHI’s general manager. “When a seal fails, it is often a critical breakdown situation and companies don’t have the time to wait for an engineering expert to visit the site to provide a diagnosis. The app is incredibly easy to use and can lead to extended mechanical seal life.”
At every stage of the pump life cycle, maintenance and smart operation can ensure that the equipment provides value to the operator and as well as continuing to perform as desired – with no nasty surprises.
-This article appeared in WWT's Pump and Valve Supplement, distributed with the April 2018 issues of WWT and WET News.
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