Newsletter Archives

Each issue of our Newsletter RUN TIMES is directed towards subjects dealing with centrifugal pump selection, operation, and reliability.

Current issue

Self-Priming Pumps- description, operation, and limitations of self-priming centrifugal pumps

May 2008 Axial Flow Pumps- A brief history and overview of axail flow pumps and thier design

April 2008 Impeller Axial Thrust Characteristics- A comparison of the relative thrust characteristics of different impeller styles, and other trade-offs when making an impeller selection.

February 2008 Lubrication of cantilever pumps- Increase service life through proper lubrication of rolling element bearings in vertical cantilever pumps

January 2008 Diagnose Low Discharge Pressure- Investigating and identifying causes of low discharge pressure

December 2007 Gas Entrainment- How gas entrainment differs from cavitation and the challenges posed by handling multi phase gas/liquid mixtures

November 2007 Specific Speed v Suction Specific Speed- A discussion of the relationship between specific and suction specific speed

October 2007 Priming Problems - Case Study- Part two of a two-part series that presents the solution for pump priming problems experienced after a pump has been out for maintenance

September 2007 Priming Problems - Case Study- Part one of a two-part series that presents the facts surrounding a plant's difficulties with placing a pump back on line after it has been out for maintenance.

August 2007 Increasing Pump Capacity- De-bottlenecking projects often call for increased pump flow rates. This issue outlines options and considerations for obtaining increased capacity from an existing pump.

July 2007 Operating Unmatched Pumps in Parallel- Parallel operation of dissimilar pumps, whether due to wear or by design, is risky business. This issue explains how the interaction of pump and system effects parallel operation

Jun 2007 Piping Alignment & Nozzle Loads- Piping induced misalignment is a frequent cause of misalignment, rubbing, and long term reliability problems. Piping stress is discussed and guidelines are provided for proper centrifugal pump nozzle alignment

May 2007 Pump Specification Considerations - Specification of a centrifugal pump for long term reliable operation benefits from collaboration between the specifier and the pump designer to ensure that the most important attributes are given priority. This issue covers topics such as planned operating range, desired efficiency, NPSHR, and cost

Apr 2007 Discharge Recirculation and Cavitation - An overview of cavitation and recirculation damage in the high pressure zones of an impeller

March 2007 How Pump Speed and Impeller Diameter Affect NPSHR - A discussion on the effects of speed and impeller diameter changes on cavitation

February 2007 Viscosity and Pump Performance - An explanation of viscosity and how increased viscosity of Newtonian fluids affects centrifugal pump performance

January 2007 Reduce the Cost of Pump Erosion- The impact that off-design operation, component design, and pump specific speed have on pump wear and replacement part cost

December 2006 Applying Variable Frequency Drives- Applying Variable Frequency Drives - This issue covers some of the economic and equipment considerations that a user should make when applying variable frequency drives to centrifugal pumps

November 2006 Obtaining Reliable Bolted Joints- Our November issue discusses the importance of the proper selection, verification, lubrication, and tensioning of metal fasteners.

October 2006 Volutes & Diffusers- covers functionality and factors influencing the selection of some of the more common volute and diffuser configurations.

September 2006 NPSHR & Impeller Trim -What effect impeller cuts have on NPSHR. A discussion of the hydraulic influences that impeller trims may have on NPSHR and the conditions under which they occur.

August 2006 Determining NPSHA- This issue describes how to calculate NPSHA and provides examples of NPSHA calculations

July 2006 Determining Total Pump Head- Pump gages readings are in units of pressure, but pump curves are drawn in terms of Total Head. This issue explains Total Head, how to calculate it from field measurements and interpret the results

June 2006Cantilever Pumps- Vertical pump applications present the user with a broad range of pump styles and prices. The most cost effective choice often changes with the design conditions. This issue covers the cantilever pump design and application

May 2006Lubricant Management & Bearing Life- 20% of all bearing failures are related to lube oil contamination and deterioration. This issue addresses the major causes of lubricant related problems and presents guidelines for improving MBTR of plant equipment

Apr 2006Angular Contact Bearing Installation- 30% of all bearing problems come from improper installation and contamination. This procedure presents the proper method for the installation of angular contact thrust bearings, as well methods for verifying correct bearing installation

Mar 2006Preventing Reverse Rotation covers reverse operation of centrifugal pumps and presents methods of inspection, prevention and troubleshooting

Feb 2006Minimum Stable Flow is the minimum flow that a pump can operate without hydraulically induced vibration. This issue discusses the three major causes of low flow instability; cavitation, recirculation and hydraulic stall.

Jan 2006Minimum Thermal Flow covers minimum thermal flow limitations of centrifugal pumps, including how to calculate temperature rise for a given flow condition

Dec 2005Operating Pumps in Parallel discusses single vs. parallel operation with different system types, and load sharing problems that may arise from poor selection or worn pumps.

Nov 2005Pump Basics Part II - System Curves shows the relationship between centrifugal pump curves and system curves. Together they are a useful tool in evaluating and troubleshooting process operation.

Oct 2005 Centrifugal Pump Basics Part I presents the basics of centrifugal pump operation. This is a very general discussion of some of the common hydraulic principles and terms used. Topics include how the pump provides energy to the liquid, the relationship between head and pressure, how flow rate is determined, and pump efficiency

Sep 2005 Shaft and Seal Misalignment Part II This issues continues last month's discussion by exploring dynamic causes for shaft and seal misalignment. Cavitation, gas entrainment, impeller imbalance and radial shaft loads are covered.

Aug 2005 Shaft and Seal Misalignment Part I Shaft and Seal Alignment greatly effects mechanical seal life. There are many factors that contribute to misalignment. This issue covers causes and corrective action for static misalignment shaft and seal misalignment.

July 2005 Do you know what's in your seal reservoir? Contaminants & seal wear materials that collect in seal reservoirs shorten seal life. This issue describes a field experience that makes a solid case for flanges seal reservoirs and regular maintenance inspections.

June 2005 Improving Mechanical Seal Life Improve mechanical seal life by eliminating misalignment and by providing proper lubrication and temperature control.

May 2005 Troubleshooting Flow Problems. Field methodologies for estimating flow in the absence of a flow meter and how to determine the cause of flow problems.

April 2005 Regenerative Turbine & Pitot Tube Pumps The final installment of this 4 part series covers two additional low-flow high-head pump styles. These lesser known pump types offer some unique advantages when handling clean liquids.

Mar 2005 Partial emission pumps are a unique design for low flow high head pump applications. This issues discusses the partial emission design and its application advantages and disadvantages

Feb 2005 Special purpose impellers and their application. Recessed impellers, screw centrifugal impellers and disc impellers are discussed. Part 2 of a 4 part series.

Jan 2005 Impeller Styles and how they play a role in proper pump selection. Part 1 of a 4 part series discusses open, semi-open, and enclosed impellers.

Dec 2004 Vertical Line-shaft pumps can be expensive to maintain. Here are some preventive measures to help improve vertical pump reliability

Nov 2004 API plan 32 Flush Systems. Avoiding seal failures because of insufficient flush flow

Oct 2004NPSHR vs. NPSHA. Understanding and avoiding cavitation

Sept 2004 discusses some of the key factors that affect centrifugal pump efficiency. Also: What is the maximum efficiency that should you expect from your pump?

August 2004: What is Specific Speed? How can specific speed be used to help specify the right pump for your application?

July 2004:Inducers:How they can help you, or hurt you, depends largely on how the pump will be operated.

June 2004: Handling abrasive solids. What causes pump wear? Choices made regarding pump style and operating speed can dramatically impact future maintenance costs.