THE PUZZLER - Joe Evans, Ph.D

Have you ever wondered why the pressure of a fluid flowing in a pipe decreases as its velocity increases? Could it have something to do with why airplane's fly? Why does 115 volts plus 115 volts equal 230 volts in some cases, but only 208 volts in others? Doesn't the pressure that a liquid exerts have anything to do with its volume? When is a watt not a volt-amp?  Is centrifugal force really a farce?   How come liquid friction, but not solid friction, is affected by velocity and surface area?

If you find these and other questions relating to pumps, motors, and electricity especially titillating, you are going to love the Puzzler. The Puzzler poses a pointed question, but that question is just the tip of the iceberg! The discussion that follows explores not only the question but also the physics surrounding it.

The current Puzzler Series consists of more than thirty brain teasers designed to expand your knowledge of mechanics, hydraulics, and electricity.

Download The Complete Puzzler Series (912 K Acrobat Document)

Download A Sample Puzzler ( 32 K Acrobat Document)

Download The New Franklin Electric Puzzler "Nikola Tesla Meets Isaac Newton" (32 K Acrobat Document)

PHYSICS FOR THE OTHERWISE, REASONABLY WELL INFORMED - Joe Evans, Ph.D

The physics course designed for those of you who believe that math is just another four letter word.  This brief review of mechanics will include motion & gravity, energy & work, the properties of matter, and vibration & waves.  It takes an almost amathematical look at these very important topics.  The first chapter, Motion & Gravity, is available now.

A BRIEF INTRODUCTION TO CENTRIFUGAL PUMPS - Joe Evans, Ph.D

This short course is intended for the new comer to the centrifugal pump environment. It is also a good review for those who are a bit rusty. Topics covered include the performance curve, centrifugal force & peripheral velocity, series operation, parallel operation, the affinity laws, friction, specific gravity & viscosity, suction lift, and NPSH. It also references several "Puzzlers" for further study of specific topics.

THE SELF PRIMING PUMP

This brief overview discusses the advantages and limitations of self priming centrifugal pumps.  It also references a "Puzzler" for a more detailed understanding of centrifugal pump priming.

THE THREE PHASE INDUCTION MOTOR - Joe Evans, Ph.D

This introduction is intended for those with little or no background in electric motors. It begins with the very basics including magnetism, direct current, and the operation of a simple DC motor. From there it moves on to alternating current, induction, and the operation of a simple AC motor. It concludes with a discussion of work, torque, and horsepower. It is an excellent primer for some of the electrical "Puzzlers".

PRESSURE SEWER SYSTEMS:  CENTRIFUGAL VS POSITIVE DISPLACEMENT

Joe Evans, Ph.D

During the past twenty years, low pressure sewer systems have become a popular alternative to traditional gravity systems. The two basic pump designs, centrifugal and positive displacement, used in these systems are as different as night and day. This short article discusses the operating characteristics of centrifugal and positive displacement grinder pumps when installed in a pressure sewer system.  Topics covered include pipeline velocity, unvarying vs dynamic flow, self limiting system pressure, operating power, and impeller / cutter design.

SEWAGE PUMP IMPELLER SELECTION - Joe Evans, Ph.D

This overview discusses the various impeller designs used in raw sewage pumping applications.  Designs covered include the major members of the radial vane family, the vortex impeller, and the centrifugal screw.   Topics include centrifugal impeller basics, design pros & cons, operational characteristics, and application selection criteria.

AIR VS OIL FILLED SEWAGE PUMP MOTORS - Joe Evans, Ph.D

Some manufacturers believe that filling a motor with oil is the only way to go while others think air to be a better solution. This paper takes an honest look at these two popular submersible sewage pump motor designs and compares the advantages and disadvantages of each. Topics covered include motor efficiency, heat transfer, bearing lubrication, maintenance, and environmental concerns.

ENERGY CONSCIOUS AC DOMESTIC BOOSTER SYSTEMS - Joe Evans, Ph.D

If you are fortunate enough (or unfortunate, depending upon one's perspective) to live off the electrical grid, efficient energy usage becomes paramount. The water pressure booster can be one of the largest loads on an inverter and, the fact that small pressure pumps and motors are quite inefficient doesn't help the situation. This paper takes a look at the various types of inverter powered pressure boosters, discusses their power requirements, and offers suggestions for reducing inverter loading and inrush current.

SUMP PUMP SAVVY

Are you a little confused by the number of different sump pumps available today? This brief review takes a look at the various designs and offers some help on where each should be used.

SIZING RESIDENTIAL BOOSTER PUMPS AND TANKS

As the title suggests, this primer is designed for the person responsible for sizing a residential water system. That person may be a salesperson, contractor, or homeowner. It discusses pressure versus flow and offers help in determining the proper amount of each.