Columns and Blogs

Specific speed is a concept developed for water turbines1 in 1915, which was later applied to centrifugal pumps (Stepanoff, 1948). Specific speed is a way to “normalize” the performance of these hydraulic machines.
Tackling 4,000 years of pump technology and evolution in only eight pages of magazine space has been like trying to summarize War and Peace in one sentence.
Temperature changes can push pipe force beyond safe limits
Keeping a close eye on pump efficiency can lead to energy savings.

It's a New Year, time to make those New Year's resolutions.

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.

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

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.

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

When selecting a pump for variable speed operation, a number of conditions must be evaluated.

Using pump system analysis, from simple to the complex

Starting can have a significant effect on the life of the winding insulation of an AC motor.

Energy efficiency and reduced consumption are important issues in the pump and motor marketplace.

The radial forces that form about the periphery of a single volute pump's impeller are proportional to total pump head, impeller diameter and vane width. They are seldom balanced, but they reach their lowest intensity between 80 and 100 percent of BEP flow.

About 900 years before Newton formulated his universal gravitational theory, the Greek philosopher Aristotle espoused something different.

In Pumps & Systems January 2007, I wrote an article about cavitation and how a collapsing water vapor bubble can damage an impeller. Since then, I have received a number of requests to address Net Positive Suction Head (NPSH) and its relationship to cavitation. Here it is in a very simple, Pump Ed 101 perspective.

A number of choices are available when connecting pumps, fans and other rotating equipment to an electric motor. There are numerous mechanical and fluid coupling designs and, in some cases, a belt drive option is available.

The frame sizes (physical dimensions) of AC motors have changed substantially through the years. Originally, they were considerably larger than those in use today. This increased size was the result of inefficiency and the need to dissipate heat.


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