Net Positive Suction Head: NPSHR and NPSHA
Addressing Net Positive Suction Head (NPSH) and its relationship to cavitation
Understanding this complex topic can help end users avoid common pitfalls.
Q. What methods are recommended for measuring a controlled-volume metering pump's flow rate, and what should be taken into account to ensure an accurate measurement? A. The following methods can be...
Pressure gauges are inexpensive components that can predict the causes of poor reliability in centrifugal pumps and prevent costly repairs and downtime.
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...
This is the first article in a four-part series. Four part 2, click here. Second only to electric motors, centrifugal pumps are usually the simplest machines in a typical process plant. Pumps...
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...
Q. What are the best materials to use in pump construction to minimize part corrosion? A. Factors to consider in the selection of materials for wetted pump components include user's experience,...
Lev Nelik answers a reader's question on thermodynamic sub-processes that are highly time dependent
Correct equipment selection and application saved an aluminum producer $36,000.
Q. Can rotary type pumps be used to pump slurries? If so, should users be aware of any special precautions? A. Rotary pumps may be used to transfer slurries when the application dictates....
Reconstruction and infrastructure upgrades require pumps made from durable materials.
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...
Q.We have recently installed several double suction between bearing pumps and would like to verify that their vibration levels are within acceptable limits. How should this be done, and what is an...
An OEM and an end user had installed a number of large, double-suction pumps for a water pumping station project (Figure 1). Soon after, they began to suspect that the pumps were a significant...
Many options are available to meet industry and application requirements.
Q. What is NPSH3, and how does it relate to the NPSHR for a rotodynamic pump? A. The Hydraulic Institute defines the required net positive suction head (NPSHR) of a pump as the net positive suction...
After reading two of my articles on power pump valves, valve springs and net positive suction head required (NPSHR), Brazilian engineer Ricardo Martuscelli emailed me to suggest that I create graphs...
NPSH: A Characteristic of All Pumps
Note from Terry Henshaw:This is the first in a year‑long series of articles called Understanding NPSH. These articles were originally prepared as class notes for the all‑day seminar on NPSH...
Pumps & Systems, May 2008 While complete packaged gas and dry chemical feed systems have been in the water treatment industry for many years, liquid metering pump packaged systems are relatively...
PumpCalcs: Be the Pump Designer
I have seen, and I am sure you have too, countless examples of installed pumps that are poor hydraulic fits. These selection mistakes are called off-design pump selections, bad actors, misapplied...
Q. What are some adverse effects that can occur from mechanical processes during pumping operations? A. Numerous mechanical processes during pumping operations are not typically duplicated in...
Pumps & Systems, May 2007If pump cavitation is not detected and quickly eliminated, significant damage can occur to the impeller and other internal components. Since cavitation (the formation and...
Magnetic Couplings, NPSH Margin &  Reverse Runaway Speed
Q. What are the effects of increasing temperature on the magnetic couplings in a rotary sealless pump?A. Eddy currents in the containment shell are one source of heat in a sealless pump. Heat is also...
The Hydraulic Institute’s New Test Standard
ANSI/HI 14.6 gives the pump community a globally accepted test standard 
for rotodynamic pumps.
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...
Centrifugal Pump Axial Thrust
The late Charlie Jackson, vibration expert at Monsanto, once told me that he was unaware of any centrifugal pump manufacturer that knew how to calculate the hydraulic axial thrust produced within the...
Due to high specific gravity, viscosity and particle size of mining materials, centrifugal pumps are continuously challenged in mining applications. New pump technology was created to efficiently move...
The Eleventh in a SeriesThe Injection of Air to Reduce Noise and DamageAs stated in an earlier article, most pumps are not suitable for handling any significant quantity of free gas. (They are just...