Columns and Blogs

Letter from a Reader

The following comments relate to scenarios described in Parts 1 and 2 of “Can Deaerators Create Pump Trips?” (Pumps & Systems, March and April 2015), which discuss handling power plant transients.

I received many comments from Pumps & Systems readers on "How to Calculate Pump Specific Speed" (Pumps & Systems, January 2015) and "How Efficien

Part 1 of this series (Pumps & Systems, March 2015) discussed what happens to a boiler feedwater (BFW) pump during plant transients.

In this two-part series, how transient events in process equipment affect other system components will be discussed. Part 1 covers how deaerators (DAs) may be affected by generator trips and how these deaerator transients may also affect system pumps.

Increased efficiency means more money saved on energy. When competitive bids are evaluated, efficiency is an important factor, especially for high-energy pumps.

Last year, “Reduce Thrust and Extend Bearing Life” (Pumps & Systems, December 2013) discussed the benefits and some potential pitfalls of adjusting the axial clearance of American National Standards Ins

For those of you old enough to remember Lawrence Welk, you’ll notice that the title of this brief column is the final quote from his show’s closing song. I am still a loyal fan of his reruns today.

In my last column (Pumps & Systems, October 2014), I explained that a capacitor’s current is totally out of phase with that of a motor’s magnetizing current.

I received a lot of feedback on my column “How Much Energy Do Pipes Remove?” in the September issue of Pumps & Systems.

Who determines where pressure gauges are located in a pump system? How close to the pump should they be, and what happens if these rules are not followed?

I hope that my last column (Pumps & Systems, September 2014) provided a clearer definition of power factor and how it can be calculated.

In past “Pumping Prescriptions” columns this year, I have discussed the procedure of piping size selection when given the process flow requirement and how this affects the pump’s power consumption. In this column, two computer calculation tools will be detailed.

Power factor (PF) is an important component of an alternating current (AC) circuit, but understanding its actual effect can be difficult. Why is PF mysterious to many of us? It has to do with the way it is explained.

In my July 2014 column, I demonstrated that three-phase voltage variation can significantly affect several alternating current (AC) motor characteristics. If that variation is large, it can also reduce motor life.

When the pump selection process starts, the required flow of the is often the only known variable for an application. For example, a system must move 2,000 gallons per minute (gpm) from a holding tank to another tank or process.

In my June column on pump and motor testing, I said that three-phase voltage variation and unbalance can have a significant effect on motor insulation life. Voltage variation is defined as the difference between the motor nameplate voltage and the incoming source voltage.

One of the supposed advantages of centrifugal pumps when compared to positive displacement pumps is their ability to operate across a wide flow range.


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