The McGraw-Hill scientific dictionary [5] states that a volute is "a spiral casing for a centrifugal pump... designed so that speed will be converted to pressure."
Specific speed is a concept developed for water turbines1 in 1915, which was later applied to centrifugal pumps (Stepanoff, 1948). Specific speed is a way to “normalize” the performance of these hydraulic machines.
Tackling 4,000 years of pump technology and evolution in only eight pages of magazine space has been like trying to summarize War and Peace in one sentence.
Temperature changes can push pipe force beyond safe limits
Rotary pumps are positive displacement pumps that use rotational, rather than reciprocating, motion during their pumping cycle. They can be designed to pump liquids, solids, gases or mixtures of all three.
I received many comments and suggestions on proper installation practices, following my article “Grouting: Pumps and Telephone Poles,” Pumps & Systems, July 2010).
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 pump.
Executives Look Forward to Increased Business in 2011
For the past two years, Pumps & Systems has used this annual “State of the Industry” space to report market uncertainty within the process industries that we cover. The economic impact of a new U.S. administration combined with stimulus package updates and a struggling overall economy has plagued these pages—making it difficult to find industry optimism.
This year, however, there is a different tone.
Using pump system analysis, from simple to the complex
Multiple pumps operating in complex systems can be synchronized and controlled by a computer. In this column, I will discuss several simplified cases, to give an idea of how pump system interactions are handled and what is involved. This column will also discuss how friction, static, and combination system hydraulics affect the system's results.
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 downtime.
There are several ways to control two identical, parallel pumps operating under variable frequency control in pumping applications.
The frame sizes (physical dimensions) of AC motors have changed substantially through the years. Originally, they were considerably larger than those in use today. This increased size was the result of inefficiency and the need to dissipate heat.
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.
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 impeller eye.
This month we will quickly look at the load types that comprise a typical AC circuit.
When the motor amps are kicking a unit offline, the first question is whether the motor or the pump is the problem.
