Critical Pump Selection Webinar – Video

critical pump selection three major issues webinar video

After the success of my webinar, I am making a recording of it available for everyone who was not able to attend, and those who wanted more time to go over the material and illustrations. Thanks again to everyone who attended the live webinar! If you want to hear about future webinars, subscribe now for […]

Should pump users care about axial thrust?

Impeller-Axial-Thrust-Diagram

Normally the user shouldn’t have to care about axial thrust.  Pump failure from an axial thrust-related problem is relatively uncommon.   But very few, if any, pumps are entirely immune to this class of problem. Why is this?   First of all, a rotating single-entry impeller wants to move in an axial direction and usually with lots […]

What is the Purpose of Minimum Flow?

Chart of pump phenomena and minimum flows

Over the years use of the term “minimum flow” has evolved.   Decades ago industrial centrifugal pump manufacturers quoted a single, relatively low value for minimum flow intended to prevent users from running their pumps to destruction.  The term “minimum flow” generally meant the lowest continuous flow the pump was permitted to operate, without reference to […]

Hydrodynamics of Pumps (2011 edition) – A Book Review

Hydrodynamics of Pumps, 2011

Hydrodynamics of Pumps by Christopher E. Brennen was first published in 1994.  Aside from my long-time professional acquaintance with the author, what caught my attention in this book are the various technical passages related to rocket propulsion turbomachines, including the Space Shuttle Main Engine.  Over the years I would hear about the technical issues with these […]

Diffuser versus volute

Diffuser

The stator section of a centrifugal pump, after flow exits the impeller, is usually either a ‘diffuser’ or a ‘volute’. The purpose of each of these two stator types is to efficiently diffuse velocity energy into pressure. Diffusers are characterized by a plurality of radially symmetric diffusing passageways surrounding the impeller. Either a volute-shaped or […]

Pump Handbook Fourth Edition – A Book Review

Turbine-Driven Mainline Pump: by Randal Ferman, Ekwestrel Corp

Years ago I owned a copy of Pump Handbook 1st Edition, by Karassik, Krutzsch, Fraser, and Messina.  While it was a book to have on the shelf, it was not my primary source of pump engineering reference material.  I obtained most of my pump technical information from other books and publications.  Eventually someone “borrowed” my […]

Downsizing the pool pump

pool-pump

About four weeks ago our swimming pool pump quit.  I don’t know the exact date, but our pool guy, Randy, left us a note.  We didn’t see the note, so a week later on his weekly visit I was home and he let me know about the pump.  The motor was frozen and couldn’t be […]

Horizontal or Vertical?

Horizontal-rotor-orientation

In selecting a pump for a given application there is sometimes the option of choosing either a vertical or a horizontal shaft pump arrangement. For instance, in a process plant certain product transfer applications might be performed by a can-type vertical pump, or a vertical in-line pump, or a horizontal process pump. Large capacity cooling […]

My first WEFTEC

Glossy-Industrial-Pump

This week I had my first WEFTEC experience.  I live in LA and WEFTEC was held at the LA Convention Center, so I drove on over to see the exhibits.  I thought I’d walk through and see everything in one day.  Wrong.  A person could physically walk through every aisle in each of the three […]

Specific Speed – Does it Matter?

specific-speed-equation

To the pump engineer or pump manufacturer specific speed is terrifically important.  To the specifying engineer or user – maybe, maybe not. The term specific speed comes up frequently in pump literature, in technical papers and is always covered in pump text books.  It is frequently heard in pump technical banter and if one doesn’t […]

Is there any confusion about NPSH?

double suction pump profile

Net Positive Suction Head (NPSH) is perhaps the most misunderstood concept in pumping technology.  The main source of confusion stems from multiple uses of the term in different but related contexts. One usage of the term NPSH is to denote the suction performance characteristic of the pump itself, independent of the system into which it […]

Multi-stage pump in-line (tandem) versus opposed impeller arrangements

inline-impellers

Common to early twentieth century multi-stage rotodynamic (centrifugal) pumps were design features for minimizing axial thrust.  At that time the thrust bearings available had limited load carrying capability.  Design solutions evolved in two principal directions. One design approach was to hydraulically balance the thrust for each stage or for the entire series of in-line (tandem) […]

The ideal pump

Turbine Driven Mainline Pump - photo credit Randal Ferman

Consider a pump that functions reliably under all possible operating conditions, no matter how abusive, including complete loss of prime or dead heading. Imagine this pump converts all of its mechanical work input into useful liquid energy output. Next, the seal or seals are zero leakage and require no flush, quench, or support system. The […]

Storm drain – what happens when the power goes out

Storm Drain

During heavy rains earlier this week a City of Long Beach storm water drainage pump was temporarily inoperable due to a power outage. This occurred during a peak storm period and is at least partly to blame for flooding in the area. A similar event at the same location is said to have occurred before. […]