Re: Pipe Fittings

Hello Balakrishnan,

Welcome to our Forum. As engineers we need to be precise with our responses and careful not to misdlead as there are many newcomers to the field of piping engineering who read what is said.

"Air pockets may form if concentric reducer is used at pump suction, which results in Cavitation, and cause damage to Pump."

Air pockets do not cause cavitation. Air pockets may reduce hydraulic capacity. Cavitation is caused by the liquid pressure being below the vapour pressure of the fluid. The NPSH may possibly be compromised by the reduced hydraulic capacity resulting from air trapped in the suction pipe. This in turn can result in the NPSHa being < NPSHr.

Refer to www.mcnallyinstitute.com for excellent papers on pumps from an experienced engineer in the field.

regards

Geoff Stone

• In PipingDesign@yahoogroups.com, "mail2rambal" <mail2rambal@...> wrote:
  >
  > Hie Friends
  >
  > This is Balakrishnan, i am a new member for this group and now i
  > working as a Material Engineer in Abu Dhabi, UAE, i really happy to
  > join this group so please add me as a friend in your list.
  >
  > And reg Mr. Mustafa clarification
  > Eccentric reducers for Pump suction to avoid Cavitation, to
  maintain
  > elevation (BOP) in rack.
  >
  > Concentric reducers for Pump discharge, vertical pipeline.
  > 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
  >
  > i hope my knowledge of Concentric and Eccentric reducers may be
  > useful for you
  >
  > Best Of regards
  > Balakrishnan R
  >
  > --- In PipingDesign@yahoogroups.com, mustafa rayees
  > <mustafa_nlg@> wrote:
  > >
  > >
  > > Dear Friends,
  > >
  > > Hi To everybody , This is mustafa ,Presently working
  > > for chilled water piping design. I am having
  > > difference of opinion to use concentric reducers.
  > >
  > > My argument is that we can use concentric reducers in
  > > horizontal & vertical pipes While my colleague is
  > > saying not to use concentric reducers in horizontal
  > > pipes.
  > >
  > > Please let me know any piping design recommend for
  > > above
  > >
  > > I will be thankfull if you give me correct information
  > >
  > >
  > > Thanks indeed.
  > >
  > > Mustafa
  > >
  > > Designing Eng.
  > >
  > >
  > >
  >
  

  ---

  
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