3 Design and Operation of Pumps Available to Purchase

The most commonly used pumps for trunkline pipeline stations are either centrifugal or positive displacement (reciprocating and rotary pumps) (Fig. 3-1). As these pumps have the most prevalent application in pipeline transmission, their theory and application are detailed in the chapter. Pipelines handling liquids in excess of about 110 cS (centistoke) viscosity will normally use rotary, positive displacement pumps both for optimum efficiency and, frequently, lower initial cost.

Centrifugal pumps are generally high-speed, high-volume units connected through speed increasers to internal combustion engines or directly to electric motors.

Centrifugal pumps offer certain distinct advantages; chief among these is the fact that the flow of liquid from them is relatively even and smooth with very few pulsations. Properly installed and operated, little or no vibration results from their use. These pumps can be used outside or in small buildings, need only light foundations, and are easily kept clean. In addition, these pumps are of comparatively low cost (capital and operation), are simple to construct and flexible to operate, and require a comparatively small space.