Actual NPSH Test - Reciprocating Pump and What is a Safe NPSH Margin for a Reciprocating Pump?
Actual NPSH Test-Reciprocating PumpPower pump NPSH tests are performed by holding pump speed and discharge pressure constant and varying the NPSH available in the system. Capacity remains constant for...
For the non-expert in pump technology, selecting the most appropriate pump technology for a specific application or process system can be challenging because many of today's pumps are so...
Acceleration Head
The Thirteenth in a SeriesIf a centrifugal pump is started with the discharge valve open too far and with a low discharge pressure, the liquid in the suction line may accelerate at a rate that causes...
Do Pumps Require Less NPSH on Hydrocarbons? Stepping NPSHR to Different Speeds
Do Pumps Require Less NPSH on Hydrocarbons?Yes.The extensive application of pumps to hydrocarbon services in the first half of the 20th century produced numerous observations that centrifugal pumps...
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 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...
A refinery's vertical pump passes the test, verifying its performance before installation.The rotating equipment engineers at BP's Whiting Refinery in Indiana approached the support team at a pump...
Packaged Pump Systems and Variable Flow Pressure Boosting
Packaged pump systems are gaining popularity due to their space saving design, simplified installation, single source responsibility and advanced control options with communication ability.Packaged...
April-Wise Pump Quiz: NPSH and Developed Head
In this installment of “Pumping Prescriptions,” I have a quiz for our readers. A typical pump system is shown in Figure 1. A centrifugal pump delivers 200 gallons per minute of water from an open...
How Poor Repairs on Boiler Feed Pumps Affect Performance and Reliability
Analyzing the poor repairs on a boiler feed pumps and how they affect the pump's performance and reliability.It is often said that a picture is worth a thousand words. This old adage could not have...
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...
Hydraulic Pump FAQs April 2011
Q.  When monitoring power consumption by a pump, what measurement methods are normally used and for what purpose?A.  Monitoring the power consumed by a pump can give advanced indication of...
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...
Performance Curves and NPSH Tests
Editor's Note: This is the fourth article the year-long series, Understanding NPSH. To read the previous article, click here. To read the next article, click here.NPSHR Shown as a Single...
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...
Hydraulic Institute Pump FAQs January 2007
Q. I have been told that centrifugal pump impellers may still cavitate when operating with NPSH Available greater than NPSH Required. Is this true? If so, why do pump suppliers show NPSHR values when...
Hydraulic Institute Pump FAQs March 2011
Q. I am aware that there are requirements for the inlet piping of rotodynamic pumps. What are the requirements for the discharge piping of a pump?A. The maximum velocity at any point in the outlet...
Hydraulic Institute Pump FAQs September 2011
Q. What are bearing isolators and how are they used?A. Bearing isolators are composed of both a stationary and a rotating component that act in concert to retain lubricant and exclude contaminants...
HI Pump FAQS
Q. How carefully must pump impellers be balanced to avoid unacceptable vibration levels when the pump is running?A. Pump impellers are typically balanced in accordance with ISO 1940 balance quality...
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...
Hydraulic Institute Pump FAQs June 2011
Q. When purchasing rotodynamic (centrifugal or vertical) pumps, how can we estimate if the efficiency of the proposed design is the best to be expected for our application?A. The Hydraulic Institute...
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...
Pumps & Systems, July and August 2007  A review of traditional metering pump designs, along with a look at some of the new technologies that are being introduced. The metering pump is a...
Pumps & Systems, July 2008Plastic is one of the most widely used materials in the manufacturing of everyday products, including food containers, toys, computers, medical equipment, building...
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...
As energy costs rise and energy efficiency becomes more important in operating pumping systems, equipment suppliers, system designers and operators will maximize the efficiency of system components to...
Pump Curve Accuracy
Digitization methods are critical when using pump selection software.First of Two PartsMore than 150 pump manufacturers present their pump performance data electronically. These digital pump catalogs...
Pumps & Systems, October 2008Q.What is a free standing baseplate and when should it be used? Are there any special design requirements?A.A free standing baseplate is designed to properly support a...
Hydraulic Institute Pump FAQs March 2009
Q. How can we tell if a pumping system is designed and operated properly? Some problems such as leaking seals are obvious, but should we watch for any other symptoms?A. A few symptoms in pumping...
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...