Columns and Blogs

Dr. Lev Nelik answers pump user questions.

Based on several of my previous Pumps & Systems articles, you probably know that I have major concerns about the off best efficiency point (BEP) operation of wastewater pumps.

Efficiency degradation in pumps can be related to three areas.

One of the major impacts on motor life is common sense—or maybe the lack thereof!

When the motor amps are kicking a unit offline, the first question is whether the motor or the pump is the problem.

There are several ways to control two identical, parallel pumps operating under variable frequency control in pumping applications.

This is a follow-up to my column on predicting centrifugal pump performance (Pump & Systems, May 2011), and offers equations that will enable the engineer to perform a partial analysis of the impeller eye.

While scheduled downtime is different from unscheduled, both can take away from a company.

This month we will quickly look at the load types that comprise a typical AC circuit.

Strengthening of bent shafts is a tricky and controversial process.

As a follow up on my AC Motors series, I thought it would be a good idea to provide a short overview of work, power and torque as it applies to the AC motor.

These days, the importance of a fresh water supply and safely-treated wastewater return to the river cannot be overemphasized. No matter how hard we try, we are still a long way from the most efficient, economic and reliable ways to ensure that our cities are properly equipped and ready for the clean water challenge.

I received many comments and suggestions on proper installation practices, following my article “Grouting: Pumps and Telephone Poles,” Pumps & Systems, July 2010).

Last month, we studied the properties and effects of resistive, inductive and capacitive loads in an AC circuit.

Several million gallons of wastewater flow through a typical wastewater treatment plant daily. Some statistics show this can amount to 50 to 100 gallons for every person using the system.
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I expect damage on this scale with a large hurricane…but one tornado? It doesn't seem possible, but it happened.
The Fluid Sealing Association (FSA) has come a long way since its inception in 1933. With today's membership representing more than 85 percent of the manufacturing capacity for fluid sealing devices in North America, the association also has an international scope.
With damages estimated at $196 billion, the disaster in Japan is certain to impact the international economy.


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