The American National Standards Institute (ANSI) sets standards for manufacturers, producers, engineers and technicians for several products. One such standard is the B73.1 for centrifugal pumps, which covers 27 pump sizes and sets key dimensions for each of the sizes. The B73.1 standard enables interchangeable pieces or products among manufacturers and brands, so the customer has more options.

The B73.1 standard centrifugal pump is commonly referred to as the ANSI pump. By adhering to the ANSI standard centrifugal pumps, the end user is guaranteed a quality product that meets specific industry requirements.

Some ANSI History

ANSI’s history dates back over a century. In 1916, four prestigious engineering organizations got together with the intention of establishing a group that could coordinate the development of standards at a national level. The U.S. War, Commerce and Navy Departments joined the non-profit group also, adding to its legitimacy.

In the 1920s, the newly formed group hosted an international conference that resulted in the creation of the International Standards Organization.

Eventually, after several name changes and years of being on the leading edge of standards development, ANSI became the generally accepted standard.

ANSI Pump Terminology

ANSI centrifugal pumps are horizontal, end-suction, single-stage, with a back pull out and an overhung impeller. But, what makes the ANSI pump special is its interchangeable abilities which allow it to interface across brands.

The shaft of the pump is oriented horizontally to the ground, whereas a vertical pump is perpendicular or vertical to the ground. Popular industrial vertical pumps are in-line or multi-stage.

The ANSI pump uses centrifugal force to push the liquid. This force is usually achieved through a rotating impeller.

ANSI Centrifugal Process Pumps

End-suction describes the fluid path as it is processed through the pump. The fluid enters directly onto the impeller and leaves from the top at a right angle (90 degrees) from the suction entry.

Single-stage indicates it has a single impeller.

The back-pull pump feature is designed so the casing can stay in the piping system whereas the rest of the pump may be pulled away.

The impeller configuration is where the bearings are at one end of the pump while the impeller is at the opposite end.

Applications and Uses

The ANSI centrifugal pumps are heavily used in the chemical industry along with food processing, refineries, ethanol production facilities and typical process plants. Because of the end-suction design and the centrifugal nature of these pumps, their applications revolve around transferring thinner liquids like alcohols and water.

Always use a centrifugal pump constructed in materials appropriate for your specific industry. For example, when manufacturing chemicals, ensure your pump seal and impeller can withstand the chemical exposure in your plant. The properties of the materials used in your pump are critical to the manufacturing process.

Centrifugal pump type driving by electric motor to transfer liquid condensate to floating storage and offloading boat

The ANSI pumps are rated at 300-psig at 300-degrees Fahrenheit and have flow rates between 10 to 5,000 gallons per minute. The head pressure ranges from about 50 to 750 feet with the horsepower going from 1.0 to a whopping 250.

ANSI pumps are most often used in transferring of the thinner liquids. Recently there has been discussion on how ANSI pumps can find their applications in the oil and natural gas market. In order to be used in these applications, they must meet additional standards and conditions including reliability in extreme temperature and humidity, the ability to withstand line shocks and compatibility with sharp bends.

The Interchangeability of ANSI Pumps

By adhering to the ANSI standard, the customer or end-user has a much better selection to choose from when buying parts. If a brand sells an ANSI pump, there is a good chance that many of the piping systems and pump parts are interchangeable.

There are some exceptions.

For example, the Gould’s 3196 ANSI pumps do not have parts interchangeable with the Flowserve’s Durco Mark 3 style. However, if you need to use a Gould’s 3106 part in the Durco Mark 3, chances are you will not have to make significant changes to the motor attachment, coupling, piping location or the piping system when installing the part.


Always check with the manufacturer or a quality online expert before purchasing the part. The pump manual may also contain information on part interchangeability.


Through collaborations with engineers and engineering organizations like IEEE and ASME, the ANSI set the B73.1 standard for the ANSI centrifugal pumps. These pumps are designed for the transport of thinner liquids and offer an interchangeability feature. This diversity gives the end user freedom to interchange the pump and some pump parts to different brands without making large changes to the piping or processing system.