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,...
The concept of “suction energy” was developed to enhance the evaluation of the NPSH characteristics of centrifugal pumps, but I fear that it misses the mark. Suction energy is defined as the...
Answers to the industry's pressing technical and management questionsQ. When purchasing new rotodynamic pumps, what type of acceptance testing is recommended?A. Purchasers of rotodynamic...
1) Only select pumps with suction specific speeds less than 11,000-less than 9,000 is even better.2) Select your pump so it never operates below 70 percent to 80 percent of its best...
In the August 2009 issue, we considered the following challenge: From the available data tables, the vapor pressure of 150 deg F water is about 4 psia, or (x 2.31) = 9 psia.Initially, when the...
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...
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...
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...
This is a follow-up to my column on predicting centrifugal pump performance (Pump & Systems, May 2011), and offers equations that will enable the engineer to perform a partial analysis of the...
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...
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...
There are two largely accepted facts about mining: 1) A mine's landscape is dynamic, and 2) Within that landscape, water is a mine's worst enemy. Navigating a mine's landscape with pumps designed to...
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...
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...
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...
Pumps & Systems, March 2007Q.What are the key requirements for good suction piping design for rotodynamic pumps?A. Good suction piping design must eliminate air entrainment in the liquid,...
One of the advantages of centrifugal pumps over positive displacement pumps is an ability to operate with a wide flow range. Since a centrifugal pump operates at the intersection of a pump curve and a...
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...
Q. I have heard that the rate of flow through centrifugal pumps can be regulated by submergence control instead of by throttling the pump discharge. How does this work, and does it damage the pump?A....
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...
Q. What is the maximum pumped liquid temperature that an end suction centrifugal pump can handle, and what must be done to a pump for it to operate successfully at that temperature?A. Limits are...
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...
Q. I see that many pumps for pumping slurries are made of either hard metals or elastomers. Why is this and which is better?A. A large variety of metals and elastomers are used for slurry pumps...
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...
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...
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...
Q. Is it true that centrifugal pumps should be built with ball bearings that have greater than normal internal clearance?A. It depends on the pump type and the conditions of service for the...
Q. What are the most probable causes of insufficient discharge flow or pressure in centrifugal pumps?A. Before looking at the pump, check the measurement of total head and rate of flow. The proper...
