Understanding this complex topic can help end users avoid common pitfalls.
  Pumps & Systems, January 2008 Critical IssuesSERO PumpSystems GmbH is a well recognized manufacturer of side channel pumps that has been in operation for more than 100 years, but SERO...
I have a pump that was used to pump natural gas condensate with a specific gravity of 0.7599 and now is used to pump water with a specific gravity of 1.005. I would be very happy if you helped me...
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...
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...
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...
The Hydraulic Institute’s New Test Standard
ANSI/HI 14.6 gives the pump community a globally accepted test standard 
for rotodynamic pumps.
The Power of Wear Rings Part Two: Efficiency
With a 50 percent decrease in clearance, efficiency is increased by 2 to 4 percent.Part One of this series discussed how wear rings impact pump reliability by increasing rotor stability—reducing...
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...
Pumps & Systems, March 2008It is common practice for the designer of a new centrifugal pump to model the new pump from an existing pump. Each dimension of the existing pump (except the shaft...
What is a Safe NPSH Margin for a Centrifugal Pump? Can You Provide Too Much NPSH?
What is a Safe NPSH Margin for a Centrifugal Pump?The Hydraulic Institute NPSHA Margin Work Group (1) recommended NPSH margins ranging from zero to four times the NPSHR (NPSHA÷NPSHR = 1 to 5). The...
What is a Safe NPSH Margin for a Centrifugal Pump? Can You Provide Too Much NPSH?
Editor's Note: This is the fifth article in the year-long series, Understanding NPSH. To read the previous article, click here. To read the next article, click here.What is a Safe NPSH Margin for a...
One of the supposed advantages of centrifugal pumps when compared to positive displacement pumps is their ability to operate across a wide flow range. Because a centrifugal pump operates at the...
Will Running Pumps Slower Help NPSH Problems?
Pumps & Systems, January 2009If your immediate answer was yes, think again-you might be surprised. Sometimes running pumps faster can actually help avoid cavitation. How so? We need to first...