from The McNally Institute
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.
If you live in the United States, it is probably the only pump standard you will ever use. Among the standardized dimensions you will find:
- The location of the pump holds down bolts.
- The distance between the suction and discharge nozzle centerlines.
- The height of the pump coupling.
There are currently three overall standard pump lengths:
- 17.5 inches
- 23.5 inches
- 33.875 inches.
The European equivalent of this standard would be the ISO (International Standards Organization) standard. Germany has their own standard called the DIN (Deutsche Industrial Norm).
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. My paper 12-5 describes these problems in detail
The main problem with this and similar standards is that they were written for packed pumps and are only now changing to reflect the increasing usage of mechanical seals. The most obvious change has been the acceptance of oversize stuffing boxes, but these standards still have a very long way to go. Ultimately the ANSI committee is going to have to accept the fact that short pumps with very low shaft L3/D4 numbers is the logical approach if American pumps are going to stay competitive.
In the following paragraphs you will find all the dimensions of the ANSI standard, end suction centrifugal pump:
The next diagram shows the detail of a typical ANSI pump and names the individual parts