Glossary A


  • Connects and aligns the power end of an ANSI pump to the wet end.

A.N.S.I. Standard

  • American National Standards Institute. A set of specifications (envelope dimensions) for centrifugal pumps manufactured in the United States

A.P.I. gland

  • A seal gland that incorporates a non sparking disaster bushing along with a vent and drain connection (quench), and a flushing connection.

A.P.I. Specifications

  • American Petroleum Institute Specifications. Usually adopted by oil refineries for petroleum applications. Includes seal gland and piping recommendations.

Absolute pressure

  • Atmospheric pressure added to gauge pressure.

Active metal

  • A corrosion resistant metal that has not been passivated. The protective oxide layer has not formed.

Affinity laws

  • They predict how capacity, head and horsepower are affected by changes in the centrifugal pump impeller diameter or shaft speed.

Air ingestion

  • Air is coming into the stuffing box because of a negative suction pressure.


  • The center line of the pump is perfectly aligned with the centerline of the driver (usually an electric motor).

Alpha sintered

  • A type of silicone carbide that does not contain silica.

Ambient heat/pressure

  • The heat or pressure in the area where the equipment is located.


  • To soften the metal by heating it to a predetermined temperature somewhere below its melting point.


  • A treatment used on aluminum to put a heavy stable film of oxide on the metal surface.

Anti-friction bearing

  • Usually referring to a ball or roller bearing


  • A description of the fluid and operating conditions that we are trying to pump or seal.

Atmospheric pressure

  • At sea level, atmospheric pressure is 14.7 psi.

AVS Standard

  • An old, obsolete standard that has been replaced by the A.N.S.I. standard.