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...
Last year, “Reduce Thrust and Extend Bearing Life” (Pumps & Systems, December 2013) discussed the benefits and some potential pitfalls of adjusting the axial clearance of American National...
My last two columns (Pumps & Systems, April and May 2014) explained how pump suction behavior depends on how suction pressure is reduced. The original video, which showed two suction pressure tests,...
I received a lot of feedback on my column “How Much Energy Do Pipes Remove?” in the September issue of Pumps & Systems. This column described the use of two computer programs that evaluate the...
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...
Who determines where pressure gauges are located in a pump system? How close to the pump should they be, and what happens if these rules are not followed? For a small pump system, the impact on the...
Editor's Note: While running a pump at its best efficiency point saves money, reduces downtime and improves performance, many plant managers are unaware of how their equipment is actually...
While running a pump at its best efficiency point saves money, reduces downtime and improves performance, many plant managers are unaware of how their equipment is actually performing. This series,...
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...
Lev Nelik answers a reader's question on thermodynamic sub-processes that are highly time dependent
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...
In past “Pumping Prescriptions” columns this year, I have discussed the procedure of piping size selection when given the process flow requirement and how this affects the pump’s power...
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...
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...
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...
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,...
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’...
Pump System Design
Last of Two Parts
Pump System Design
First of Two Parts
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...
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...
Resonant Frequencies
Last of Two Parts
Resonant Frequencies
From vertical pump rotors to bacteria, resonance has similar effects.
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...
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,...
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....
When the pump selection process starts, the required flow of the is often the only known variable for an application. For example, a system must move 2,000 gallons per minute (gpm) from a holding tank...
Specialty Materials Help Improve Pump Reliability and Save Energy
Efficiency degradation in pumps can be related to three areas. Worn clearances between the wear rings of the impeller and the casing can increase leakage and drop the volumetric efficiency of the...