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. ANSI B73.1: this is a standard that applies to the construction of horizontal end-suction centrifugal pumps. It is the intent of this standard that pumps of all sources of supply shall be dimensionally interchangeable with respect to mounting dimensions, size and location of suction and discharge nozzles, input shafts, base-plates, and foundation bolts.