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Why concentric reducers are not used in pump discharge lines?

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Question added by PRANABESH CHAKRABORTY , Lead Manager , H.A.O. Solar
Date Posted: 2014/10/28

Concetric reducers are used in pump discharge lines not suction lines.

azhar ansari
by azhar ansari , Piping Designer , Denfab Consulting Engineers Pvt. Ltd

Air pockets may form if concentric reducer is used at pump suction, which 

results in Cavitation, and cause damage to Pump. To avoid this problem, 

Eccentric Reducer with Flat Side Up (FSU) is used in Pump Suction.

magdy abd al nour
by magdy abd al nour , HVAC Site manger , First United Co.

eccentric reducer in suction and concentric in pump discharge

Patrick Bou Chedid
by Patrick Bou Chedid , Resident Mechanical Engineer, QA QC(LEED AP BD+C) , S.E.G SOCIETE D'ENTREPRISE ET DE GESTION

In the past the theory was that pump suction reducer should be eccentric flat on top.

But the expert Igor Karassik after his several tests up to1995 before his death at84 years old he agreed that if the supply source was from above the pump, the eccentric reducer should be installed with the flat (horizontal) surface at the bottom. Entrained vapor bubbles could then migrate back into the source instead of staying near the pump suction. If the pump suction piping entered after a long horizontal run or from below the pump, the flat of the eccentric reducer should be at the top.

Sasa Stavric
by Sasa Stavric , Engineer Techinician , Kombinat

Pump suction needs to be an eccentric reducer that always flat on top.Eccentric reducer on the pump suction reduces pump cavatation catching air.

the pressure with which the fluid discharges from the pump will be reduced up to certain extent. even though pump does not increase the pressure.

its because expansion at the reducers should be taken at the gradually . in order to prevent the cavities or air bubbles .

 

The pump discharge reducer doesn't matter if it's concentric or eccentric. It's the pump SUCTION that needs to be an eccentric reducer that is always flat on top (F.O.T.) The eccentric reducer on the pump suction reduces pump cavatation (pump catching air).

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