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nt
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Join Date: May 2014
Posts: 30

Why are the Reducers at Pump Inlet and Outlet Different?

12/22/2014 10:40 PM

Hello Dear!

Excuse me

The reducers installed at inlet and outlet of Pump set are not same. One side is CONCENTRIC reducer and another side is ECCENTRIC reducer. Why does using like that? Can't using as uniform equipment on both side? Please sharing for this knowledge.

Best regards

NT
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Noudge79
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#1

Re: why different reducers at pump in & pump out?

12/22/2014 10:50 PM

For centrifugal pumps it is usual and good practice that eccentric reducer will be at suction side. This is to assure no air is trapped on it. Now what happens when there is air on the suction line?

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Tornado
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#2

Re: Why are the Reducers at Pump Inlet and Outlet Different?

12/22/2014 11:15 PM

Note also that the eccentric reducer to the suction should be flat on the top side.

(There is a possible, but unusual, exception.)

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Noudge79
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#3
In reply to #2

Re: Why are the Reducers at Pump Inlet and Outlet Different?

12/22/2014 11:44 PM

Exactly, Tornado.

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lyn
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#4
In reply to #2

Re: Why are the Reducers at Pump Inlet and Outlet Different?

12/22/2014 11:45 PM

Supply above the pump?
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Tornado
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#5
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Re: Why are the Reducers at Pump Inlet and Outlet Different?

12/22/2014 11:51 PM

Yes, and if the horizontal run to the pump is short. Not really the best layout, but sometimes space restrictions prevail.

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phoenix911
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#8
In reply to #2

Re: Why are the Reducers at Pump Inlet and Outlet Different?

12/26/2014 8:45 AM

On sanitary operations we would put the eccentric flat side down on the inlet, for positive drain.

If the inlet is being reduced to/for the pump.

Also, any change in inlet/outlet on a pump there should be at least at a minimum 5 pipe diameters of straight length on the inlet and 3 pipe diameters of straight on the outlet of the pump.

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Anonymous Poster #1
#6

Re: Why are the Reducers at Pump Inlet and Outlet Different?

12/23/2014 3:49 AM

http://www.pumpfundamentals.com/centrifugal-pump-tips.htm

An interesting link:
http://cr4.globalspec.com/thread/77398
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dhayanandhan
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#7

Re: Why are the Reducers at Pump Inlet and Outlet Different?

12/23/2014 12:10 PM

Dear Mr. nt,

The Velocity for Suction Pipe and Delivery Pipe is defined in the Standards, depending upon the permissible loss of head, viscosity of the fluid to be pumped.

For example for pumping water - the Suction Side Velocity is taken as 1 M/Sec., and for Delivery Side, the Velocity is taken as 2 M/Sec. It is to be noted that, with in the pump the velocity of water and hence pressure is more and hence for a given flow rate, the area required will be less for the pump.

But the suction side and delivery side velocity is to be as per standards, and hence for the same flow the area and hence Pipe Diameter will be higher than that of the pump inlet and and pump outlet side. Therefor the reducers are necessary.

It is preferred to have eccentric reducers than the concentric reducers. In the eccentric reducer for the suction side, the horizontal portion should be on the top, for delivery side the horizontal portion should be at the bottom so as to avoid air lock.

DHAYANANDHAN.S
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Kevin LaPaire
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#9

Re: Why are the Reducers at Pump Inlet and Outlet Different?

12/27/2014 2:08 PM

Everyone seems to be thinking water type pumps. For hydraulic applications there are rules about flow rates in the system which I learned many eons ago. All lines are sized according to the following general rules for flow rates:

inlet to pump - max 5 FPM

pressure line - Max 20 FPM

return line - max 10 FPM

Lines are sized to reduce line losses(pressure), prevent cavitation(suction) and limit back pressure(return) in the overall system. I don't know where the numbers came from, but that is what I learned from my hydraulic system experts.

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Tornado
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#10
In reply to #9

Re: Why are the Reducers at Pump Inlet and Outlet Different?

12/27/2014 2:32 PM

Those should probably be fps rather than fpm.

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Anonymous Poster (1); dhayanandhan (1); Kevin LaPaire (1); lyn (1); Noudge79 (2); phoenix911 (1); Tornado (3)

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