Centrifugal Pump Rotation
Because suction and discharge nozzle locations are affected by pump rotation, it is important to understand how the direction of rotation is defined. According to Hydraulic Institute standards, rotation is defined as clockwise or counterclockwise by looking at the driven end of a horizontal pump or looking down on a vertical pump. To avoid misunderstanding, clockwise or counterclockwise rotation should always be qualified by including the direction from which one looks at the pump.
The terms inboard end or drive end (the end of the pump closest to the driver) and outboard end or nondrive end (the end of the pump farthest from the driver) are used only with horizontal pumps. The terms lose their significance with dual-driven pumps. Any centrifugal pump casing pattern can be arranged for either clockwise or counterclockwise rotation, except for end-suction pumps, which have integral heads on one side. These require separate directional patterns.