Public works officials who manage the nation's wastewater treatment plants (WWTPs) would universally agree that a "weak" link in any plant's process chain can cause big-and often expensive-problems....
VFDs and sensorless technologies are often the best solution for controlling and protecting a centrifugal pump system against failure.
Pump Challenge #1 - an impeller cut problem - is an application of the Affinity Laws to reduce the motor amps and solve a motor tripping problem. The full details of the challenge can be seen by...
Solutions to Common Centrifugal 
Pump Problems
The first step in troubleshooting involves examining the pump, the fluid and the system.
Specialty Materials Help Improve Pump Reliability and Save Energy
Efficiency degradation in pumps can be related to three areas. Worn clearances between the wear rings of the impeller and the casing can increase leakage and drop the volumetric efficiency of the...
For many of us, water is the only liquid that flows through our centrifugal pumps. Consequently, specific gravity (SG) and viscosity are not factors when sizing them. But, if you work with other...
Last month we learned that the power required by a centrifugal pump is directly proportional to the specific gravity (SG) of the pumped liquid. We also learned that as long as the liquid has a...
Stable and Unstable Pump Curves
A “stable” curve is important for pump operation, especially for pumps in parallel operation. The higher the energy level and the more critical an installation, the more the pump curve could...
There are many indications that end users should not use a valve for flow control—or at least not to extremes.
KSB's facility in Frankenthal, Germany produces 85,000 standard centrifugal pumps per year.
By lifting wastewater to a higher elevation, pump stations are installed either in the gravity system or at the headworks of the wastewater treatment plant. Areas not suitable for gravity systems may...
Success Story of the Year 2009
The International Paper plant in Courtland, Ala., had experienced problems with a white water pump on a paper machine since the plant installed the pump in the late 1970s. The problem pump experienced...
Fighting Falling Lake Levels with an On-Shore Centrifugal Pump Commerce, Texas, relies on nearby Lake Tawakoni for supplying water, but falling lake levels were creating problems for its vertical...
Suction Calculators
Last month I reviewed an Excel-based Radial Thrust Calculator and showed how it can predict the magnitude of unbalanced radial thrust when a centrifugal pump is operated to the left of BEP. This month...
Suction Specific Speed (Part One)
The Eighth in a SeriesNormalizing NPSHOur attempts to normalize or classify water turbine hydraulic performance culminated in 1915 with the development of the specific speed concept, which was later...
Suction Specific Speed (Part Three): Using Suction Specific Speed to Establish Adequate NPSHA, net positive suction head, NPSH
Tenth in a SeriesA number of technical papers (1, 4, 7, 8) have shown that the maximum damage rate to centrifugal pumps, at least in water services, typically occurs when the NPSHA is in the range of...
Suction Specific Speed (Part Two)
Graph of Minimum Continuous FlowsIn 1982, Richard Dubner of Chevron developed a graph for use in establishing minimum continuous flow rates for centrifugal pumps (see Figure 1). It allows a lower flow...
Recently, I received a call from a plant operator in Ohio. He said, “We have a big contract from a customer to supply multiple oil heating systems and have just completed the first unit. It is ready...
Suction-Side System Design; If You Do Not Have Enough NPSHA; Resistance of Materials to Cavitation Damage
Final Article in a 14-Part SeriesSuction-Side System DesignCentrifugal PumpsFigure 1 shows most of the features discussed below.  Straight Run Into Suction For satisfactory operation, a...
Testing Centrifugal Pumps in the Field
The performance curves generated by many pump manufacturers are based on results obtained in their test facilities under tightly controlled conditions. The testing techniques used in the field can...
The DEF Market
The diesel exhaust fluid market creates opportunities for pump manufacturers.Growth and innovation in industrial pump design and operation are often driven by outside forces. A common force is the...
The Function of the Volute
Misunderstood pump element serves to minimize mixing lossIt is a common misconception in the U.S. pump industry that the function of the volute is that of a diffuser: to convert velocity into...
The Impact of the Area Ratio
In March 1980, I attended the ASME symposium on Predicting the Performance of Centrifugal Pumps and Compressors in New Orleans. I was about three rows from the podium, sitting next to a fellow who...
Recently I was involved in a discussion with some folks from Chevron about the effects of viscosity on centrifugal pump performance. Here are some excerpts from our discussion: "The Hydraulic...
Editor's Note: This is the second article the year-long series, Understanding NPSH.  Definition of NPSHThe margin of pressure over vapor pressure, at the pump suction nozzle, is Net Positive...
Use Simple Pump Troubleshooting Methods Before Rushing to Fancy Analysis
When the motor amps are kicking a unit offline, the first question is whether the motor or the pump is the problem. Before any sophisticated troubleshooting methods are applied, most experienced...
This study establishes the relevant characteristics of sludge and how they affect the performance of pumps with a swept-back leading edge impeller and relief groove in the volute and head losses in...
Transporting large pre-fabricated modules to a remote, hostile and storm-ravaged environment is difficult and not without risk. For this reason, centrifugal pumps were chosen to play a key role in...
3-D laser scanning is a relatively new technology that yields a three dimensional virtual record of a real object. The concept is simple and similar to police radar, but requires the power of modern...
In the late 90s, I used Excel to develop a simple graphical system that showed the variable speed performance of a pump based upon its published 60-hz H/Q curve. I have modified it to model several...