Industry Outlook: Making The Next Logical Move

EP Editorial Staff | August 1, 2009

david_orlowskiInpro/Seal has been helping customers in both good and not-so-good times for 32 years—ever since our invention of the bearing isolator. From day one, we have strongly emphasized customer service. As a result, “Same-day,” NOT “Some-day” shipments of even custom products are a way of life for us. In fact, we encourage our customers NOT to inventory Inpro products, as we provide same-day shipments at no extra charge. We’ve been doing these things for a long time, and we’ll continue doing them!

The need for new technologies
More recently, however, we have become particularly concerned about energy conservation, believing that reduction of electrical usage is crucial to the building of a sustainable future. We’re now working hard to develop the very types of technologies that will help our customers do just that.

Most end-users are well aware of the energy-intensive, short-lived characteristics of contact seals in bearing protection—that’s why countless operations have now turned to non-contact bearing isolators. Everyone, however, is not as knowledgeable as they should be with the use of Variable Frequency Drives (VFDs) for powering centrifugal pumps and fans.

Alternating current (AC) motors normally run at a constant speed, according to the frequency of the line supply and motor architecture. Only direct current (DC) motors inherently run at variable speed, according to demand. To control the quantity of flow and the system pressure of a centrifugal pump or fan, valves downstream would open or shut. That’s tantamount to constantly driving your car at 100 mph and trying to control it with the brake—it’s both inefficient and destructive.

Protecting your VFDs
Now, consider the VFD, something that has been drastically modified and improved over the past few years. It lets the common 3-phase AC induction motor run at variable speed according to system demands and do it with very significant savings in energy consumption.

For example, if a motor is adjusted back to 90% speed, flow will be reduced by 10% and the pressure that is produced will be around 80%. On the other hand, the power requirement will be reduced to 73% of what would have been required at full speed. That’s a power savings of almost 30%!

The demand for VFDs is increasing exponentially. According to industry sources, 40% of the motors being produced and installed throughout the process industries are already equipped with these types of drives. Soon, according to those same industry sources, that number is expected to increase to 80%.

Centrifugal pump selections are usually made with the maximum flow rate and pressure head performance in mind. Only rarely does a pump operate at that point of the system-head curve. The drive motor is capable of handling the pump at the maximum performance rating.

If a pump operates at the best efficiency point (BEP) at the maximum impeller trim, it is easily cut back in speed so as to follow the affinity laws downward as they intersect the reduction of impeller velocity. That’s like trimming the impeller on the fly, while reducing flow, head pressure and energy requirement according to system demand—all without an energy-wasting control valve in the pipeline.

Only easily mitigated stray shaft currents generated by the VFD and normally routed through the bearings to ground could contribute to early maintenance costs. A current diverter ring (CDR) can solve that problem. That’s why we’re now producing these products.

As we at Inpro/Seal see it, entering into the arena of bearing protection from stray electrical currents is only a logical move—and another great way to help our customers. MT

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