Ecc Reducer On Pump Suction Piping

[TBP]

Is there ever a set of circumstances in which it desirable to install an eccentric reducer in a horizontal suction line to any pump (an ammonia pump, in this case) with the flat side down instead of up? In any installations I've seen, been involved with, or read about - for any pump - the flat side of the reducer is on the top, to eliminate the possibility of an air or vapour pocket. Does anybody know of any exceptions to this rule?

 

[quark]

I am not quite sure but I did(1" x 2 1/2") it for one purified circulation pump (totally looped even at end points) with same suction and discharge static heads. I had a debate with the piping guy but I went with my gut feeling. I thought that there will be flow separation if we keep the flat side up in this case. That didn't give me any problems but I never checked for the advantage either.

 

[katmar]

Standard practice is to put the flat side down if there may be small solid particles present.

 

[shahyar]

As Katmar, we put "Flat on top" reducers in slurries. Iudgement is important when you have dissolved gases plus solid particles in the liquid.

 

[abcmex]

Dear TBP,
I read in one piping book that it is recommended for melted materials where you may use heat tracing.

I had exactly the same discussion not long ago about liquified ammonia; it was requested an excentrical reducer flat botom. the reason was to allow the gas to go back. I am not convinced.

rgs