Pumps centrifugal Selection guide

Figure 5.6. Centrifugal pump selection guide. Single-stage >1750 rpm, multi-stage 1750 rpm...

Selection of pump for a given appHcation is not a trivial task. Often more than one pump type can accomplish the required job. Thus a final choice on a pump type is often a result of personal experience and usage history. As a rule of thumb, the choice of a kinetic, such as centrifugal, or a positive displacement pump is made on the basis of the specific speed. Whereas specific speed is appHcable primarily for centrifugal but not positive displacement pumps, the US value can be used as a guide. Generally, for calculated values of specific speed, eg, nS > 10 [NS > 500), kinetic-type pumps are usually selected. For nS < 10 [NS < 500), positive displacement pumps are typically appHed. 

Materials selection for centrifugal pumps is contained in API 3 610, Appendixes E and F. Another source of information is API s Guide for Inspection of Refinery Equipment, Chapter II. In addition, both NACE Group Committee T-8 on Refining Industry Corrosion and the API Corrosion Committee publish minutes of their semiannual meetings. An index of Group Committee T-8 s minutes has been produced so that information on any topic discussed can be located. 

Later in this chapter, we formally set out the tools used for sizing head losses. The elements used for selecting pumps are introduced in Chapter 5. Different types of pumps are presented (centrifugal pumps, axial pumps, positive displacement pumps), and the reasoning that guides the choice of a pump, based on the levels of flow rate and head to be delivered, is discussed. 

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