Facility managers who rely on industrial pumps for the various liquid-transfer duties in their manufacturing processes can be excused if they occasionally think that once the pump has been purchased the majority of the heavy lifting has been completed. It is easy to see why this mindset might become prevalent. After all, identifying the right pump for the right process requires a lot of time and due diligence, from performance reviews to cost estimates, to even soliciting opinions from other manufacturers.
In reality, studies of different types of manufacturing operations have indicated that, when all is said and done, the purchase price of a pump will only be 10% to 15% of its total life-cycle cost, with “life-cycle cost” defined by The Hydraulic Institute as the “total lifetime cost to purchase, install, operate, maintain and dispose of the pump.”
Based on that definition, the reality is that cutting a check for the purchase price of the pump is only the first of many potential expenses that will be incurred over the pump’s operational lifetime, which – if the operator is fortunate – can be as long as 20 years or more. Hand in hand with that, pumps are said to account for between 20% and 25% of the energy usage in a manufacturing operation. Therefore, it is imperative that facility operators analyze their pre-buy research not only from an initial-cost perspective, but also from a total life-cycle cost viewpoint.
To do that, there are five cost factors to consider when attempting to arrive at a trustworthy figure for what a pump’s total life-cycle cost may be. Let’s take a closer look at all five:
- Capital Cost
As mentioned, capital expenditure – or CAPEX – in the amount of money paid to actually purchase the pump is the first and most obvious life-cycle cost. But identifying and optimizing that CAPEX cost involves much more than comparing and contrasting price tags.
The first consideration should be identifying the pumping technology that best suits the needs of your liquid-transfer processes. Usually, this comes down to a choice between positive displacement (PD) and centrifugal-style pumps, with the type of technology that is ultimately chosen having huge implications regarding the total life-cycle cost of the pump.
In many instances, final pump selection can come down to an either/or choice:
If a PD pump is chosen, will its operation require the use of a gear reducer or speed-reduction device? If it will, that is an added upfront cost that must be considered since centrifugal pumps do not need speed reducers.
There have been a number of significant advances recently in the development of leak-free or seal-less pumps. These types of pumps, however, are generally more expensive than sealed pumps, but on the other hand, an inventory of replacement seals will not need to be purchased, stocked and tracked.
Within the PD realm, air-operated double-diaphragm (AODD) pumps are a unique technology in that they do not need a traditional electric or fuel-powered motor to operate and have no couplings or seals that need to be maintained or replaced. The only daily operational cost is paying for a supply of air, but this means that the facility must be able to accommodate that capability. AODD pumps also do have a number of wear parts that will need to be monitored, including their diaphragms, balls and valve seats.Particular to the chemical-manufacturing industry, over the years centrifugal pumps have become the default liquid-transfer technology in many of the world’s chemical-processing systems. Because of this, many chemical processors will always choose a centrifugal pump because they know how they operate, are familiar with their benefits and are confident they will get the job done, no questions asked.
The problem with this mindset is that it means that many chemical-processing systems have been designed around the needs of the pump, rather than the needs of the system. For example, design engineers will design their systems so that raw materials can be blended or heated in a way that their viscosity is brought to a level that enables them to be handled by a centrifugal pump. In this case, they are reconditioning the material to fit the need of the pump, regardless of any potential life-cycle cost impact.
The operator, in addition to getting the viscosity to a centrifugal-friendly level, must also ensure that the pump continues to operate at its Best Efficiency Point (BEP), generally believed to be a window in which the pump operates at 80% to 110% efficiency levels. Any time spent operating outside the BEP can result in shaft deflection that will place higher loads on the pump’s bearings and mechanical seal, which can damage the pump’s casing, impeller and back plate. This domino effect will lead to higher maintenance and part-replacement costs that – teamed with the costs required to actually keep the pump operating at its BEP – will increase total life-cycle costs.