ANSI is the American National Institute Pump Standard. It is a set of inch dimensional standards that describe the envelope dimensions of a back pull out, centrifugal pump. The American National Standards Institute (ANSI) established manufacturing criteria for centrifugal pumps to ensure that dimensional, material composition and safety specifications meet the demanding needs of the chemical processing industry.The centrifugal pump standard known as ASME B73.1 can trace its origins as early as 1955, when efforts to develop chemical pump standards began. This later evolved into the American Voluntary Standard in 1962 and, in conjunction with a similar Hydraulic Institute standard, became ANSI B73.1 in 1974.
The equivalent of this standard would be the ISO (International Standards Organization) standard. In the ISO community, standard 2858 were first published in 1973 and contained dimensional (bare pumps only) and nominal duty points, but free of technical requirements. It wasn’t until 1986 that construction standards were published for ISO pumps as “Technical specifications for centrifugal pumps – Class II”. The current version (second edition) was issued for publication in 2002. 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(API 610) to create a single standard for centrifugal pumps. The result of this merger is going to be a combination of the problems inherent in both these standards.
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.
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