This is a general explanation. Since pump suction pipes are usually one or more pipe sizes larger than the suction inlet of the pump a reducer is required. The eccentric reducer is used to help avoid the creation of a vapor space leading to cavitation and areas that are not as drainable as desired. In order to prevent a vapor pocket the positioning of the eccentric reducer is important. When the source of the pump’s suction fluid is above the pump then the eccentric reducer should be installed with the flat side on the bottom (FOB). When the source is lower (i.e. pit, etc.), then the flat side is installed on top (FOT). There are more considerations to be addressed on pump suction piping and a good source is Goulds Pumps manual.
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<a href="/group/PipingDesign/post?postID=VvRkCoYU43Z-7wbjEtKAxAzTeB_LszgDeeiZKPgmPCuuOBR6RH7eYwGAH4w5UmkuQWLs4irZnunlsM3sOHRchQ">dennied2003@yahoo.com</a>, can you clarify that statement? It seems to be at odds with conventional wisdom. Don't vapors tend to accumulate in higher spots?
Maybe you could talk to Jacques at www.fluidedesign.com , he knows a lot about pumps and NPSH.
Paul Received on Fri Mar 12 23:36:00 2004
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