by Joe Evans
November 29, 2012

Memorization and learning are two different things. As I look back on my own education—formal and real life—most of the facts and figures that I memorized are long gone. Even today, routine details seem to slip in and out of memory based on how often I use them.

In contrast, the majority of the things that I truly learned are still with me. They may need a bit of jogging here and there, but for the most part, they can be resurrected in amazing detail.

I am sure this is why I became interested in science and, particularly, physics. Physics is the basis for all the sciences and is at the core of engineering. It is not merely a collection of facts, but a method of learning.

Some degree of memorization is required, but most of what we memorize is used repeatedly as building blocks in the learning process. Like the random facts we deal with daily, important equations will sometimes slip away. However, their understanding remains vivid, and they seem satisfied to hide quietly until they are needed again.

The difference between memorization and learning is the difference between “what” and “why.” “What” tends to look for a quick and dirty fact to explain a process. “Why” tends to delve deeper, attempting to explore the basics surrounding the process.

Knowing that a process occurs is of limited value. Understanding why a process occurs explains it and provides us with a pathway toward understanding related processes.

The Puzzler

The paragraphs above comprise the introduction to the “Puzzler” series that I developed in the late 1980s for my weekly employee training sessions. It was patterned after the one presented by the Tappet brothers on the popular radio show Car Talk.

My weekly Puzzler posed a question about pumps, motors and controls, and my employees had a week to think about it and research it.

The following week, they presented their answers and the reasoning that gave rise to those answers. Its entire purpose was to promote learning rather than memorization.

Pump Training

Pump system training can be rewarding and frustrating. I wish I could say that most of my seminar audiences follow the 80/20 rule—80 percent are truly interested and the other 20 percent are just there for the education credits. It is more often 60/40, and I have done a few where 40/60 was the norm.

I find it frustrating that so many of us do not realize that a thorough understanding of subjects related to the tasks we perform can help us do our jobs better. Are we lazy, not very smart or do we just not care?
I believe that it is due in part to a different public school education system than the one I experienced back in the 1950s and 1960s. If you would like to see a comparison of my take on education then and now, download “Why Newton Invented Calculus” from

Even college students who major in mechanical and civil engineering receive little or no education on pump hydraulics. That is why I spend a lot of my time educating young engineers on this topic.
It is rewarding to have a student ask a seemingly unrelated question after a class. In reality, however, it was not unrelated. What the student learned in the class allowed him or her to apply it to different but related processes.

The Importance of Pump Theory

Some tell me that I present too much pump theory. However, I believe that a fundamental understanding of what goes on inside a pump is necessary if we are to:

  1. Select a pump
  2. Operate a pump
  3. Maintain that pump properly

Otherwise, we tend to follow Einstein’s definition of insanity and do the same thing over and over again while expecting different results. Unfortunately, some pump users and politicians have a lot in common.

Two examples of theory that are also practical are:

  1. Specific speed (Ns)
  2. Suction specific speed (S)

Many believe that Ns and S are the stuff of design engineers, but they are great indicators of potentially dangerous conditions. They are useful because:

  1. Specific speed can predict the radial forces that can cause premature shaft, seal and wear ring failure.
  2. Suction specific speed provides the safe operating window that can prevent the onset of suction recirculation and resulting cavitation.

Both theoretical values are critical to pump selection and allow operators and maintenance personnel to recognize potential problems in existing installations. There are many more.

The Goal of “Pump Ed 101”

A thorough understanding of pumping systems is the goal of “Pump Ed 101,” and I will continue to pound you with these theoretical but practical subjects.

I wish all my readers a happy holiday season and a prosperous New Year.