There are many indications that end users should not use a valve for flow control—or at least not to extremes.
Recently, I received a call from a plant operator in Ohio. He said, “We have a big contract from a customer to supply multiple oil heating systems and have just completed the first unit. It is ready...
This article was written in response to the following question from a reader: Could you explain how an ANSI pump impeller’s clearance setting (both an open-vane impeller with back pump-out vane...
Pump designers know that designing a complex pump is easier than designing a simple one. Having my own roots in design, I know how tempting it is to add another feature and a tweak to a pump design....
Resonant Frequencies
Last of Two Parts
Summer Pump Quiz—Solutions
Last of Two Parts
Summer Pump Quiz—Cavitation
Let’s start with the basics: boiling is the vaporization of liquid. In a kitchen, water boils at high temperature—100 C (212 F). These temperatures are at atmospheric pressure, however.Liquid can...
Resonant Frequencies
From vertical pump rotors to bacteria, resonance has similar effects.
Do Vibration Measurements Depend on Probe Placement and Probe Type?
Typically, vibration measurements are taken with a handheld accelerometer probe in four places:Pump outboard bearing housingPump inboard bearing housingMotor inboard bearing housingMotor outboard...
Shaft & Bearing Material Selection
How important is the hardfacing requirement below the sleeve bearings in the 416 stainless steel (ss) shaft of a vertical turbine pump used to move condensate? Consider an example with a condensate...
Pump System Design
Last of Two Parts
Pump System Design
First of Two Parts
This article will discuss a case of how measuring vibration can help detect cavitation issues. It will also show how this can relate to a bigger problem at the plant. Sometimes a proposed change of...
Positive displacement (PD) pumps do not function well if the discharge is blocked. Unlike centrifugal pumps, they have little tolerance for flow restriction. A piston pump will try to continue...
Part 1 (Pumps & Systems, August 2012) discussed an example in which neglecting corrections for velocity head and gauge elevation did not introduce significant errors in the calculations. Part 2...
How Important Is Accounting for Velocity Head and Gauge Elevation? (Part 1 of 2)
For a quick estimate of pump head in the field, the discharge pressure gauge is read. This number is multiplied by 2.31, and operators can get a rough value of the pump head. If the gauge reading is...
10 Steps for Proper Pump-Pipe Alignment
The initial version of this procedure was published several years ago by me. Since then, a large amount of feedback has been accumulated. The most recent reflection appeared in the March 2012 issue of...
Wastewater Debris Disposal Options
Strange things can enter municipal wastewater processing plants. While the bulk of the volume is water, the main challenge is what is carried along with it. As the influent enters the plant, the first...
The standards for repair will begin with a standard for vertical turbine pumps.The pump industry is undergoing renewed interest in the technical aspects and quality of repairs. Pump users’...
On-Line Vibration Analysis Versus Vibration Trending
Vibration monitoring can be an early warning of problems developing inside rotating machinery. As companies migrate from a passive run-to-failure approach to a proactive/preventive maintenance method,...
Repair Standard for Vertical Pumps
Since the original publication of this draft standard in the January 2008 issue of Pumps & Systems, I have received feedback, encouragement, numerous questions and criticism. The draft listed...
Thermal Stress Affects Pipe Forces on Pumps
Temperature changes can push pipe force beyond safe limitsTo view all of the articles in the Thermal Stress Affects Pipe Forces on Pump series, click here.Two major headaches for pump plant...
Handling Downtime
While scheduled downtime is different from unscheduled, both can take away from a company. An effective reliability program, however, will minimize unplanned downtime and maximize scheduled...
How to Size Shims
I received many comments and suggestions on proper installation practices, following my article “Grouting: Pumps and Telephone Poles,” Pumps & Systems, July 2010). My long-time friend and...
This column presents a discussion between myself and pump users regarding some of their questions, concerns and preferences about materials of construction that they consider for their applications....
Newtonian and Non-Newtonian Fluids
How viscosity affects centrifugal pumpsThe Hydraulic Institute published a standard to account for the effects of viscosity of centrifugal pump performance. Effects of Liquid Viscosity on Rotodynamic...
Parallel--Not So Parallel--Operation
Using pump system analysis, from simple to the complexMultiple pumps operating in complex systems can be synchronized and controlled by a computer. In this column, I will discuss several simplified...
Shaft Straightening Methods and Procedures
First of Two PartsStrengthening of bent shafts is a tricky and controversial process. A bent shaft can cause many pump problems—including wear of supporting bushings, leaky seals, high vibrations,...