11.1 CENTRIFUGAL PUMPS
A centrifugal pump is a kinetic machine converting mechanical energy into hydraulic energy through centrifugal activity. A centrifugal pump is one of the simplest pieces of equipment. Its purpose is to convert energy of an electric motor or engine into velocity or kinetic energy and then into pressure of a fluid that is being pumped. The energy changes occur into two main parts of the pump, the impeller and the volute. The impeller is the rotating part that converts driver energy into the kinetic energy. The volute is the stationary part that converts the kinetic energy into pressure.
Liquid enters the pump suction and then the eye of the impeller. When the impeller rotates, it spins the liquid sitting in the cavities between the vanes outward and imparts centrifugal acceleration. As the liquid leaves the eye of the impeller a low pressure area is created at the eye allowing more liquid to enter the pump inlet.
11.2 ANSI END SUCTION PUMP
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| Figure 11-1: (Courtesy Flowserve) | Figure 11-2: Section of ANSI Pump |
ANSI is an acronym used to describe the American National Institute Pump Standard. The standard evolved from the American Voluntary Standard (AVS) that was first proposed by the Manufacturing Chemists Association in the nineteen fifties. It is a set of inch dimensional standards that describe the envelope dimensions of a back pull out, centrifugal pump. The ANSI standard has gone through several revisions since it was originally adopted and there is lots of talk about combining it with the present API (American Petroleum Institute) standard to create a single standard for centrifugal pumps in the United States. The result of this merger is going to be a combination of the problems inherent in both these standards.
