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gsuhas
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Eccentric Reducer as Compared to Concentric Reducer

09/07/2019 4:11 AM

Does pressure drop across eccentric and concentric reducers of same size is different with water as service liquid?
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Tornado
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#1

Re: Eccentric Reducer as Compared to Concentric Reducer

09/07/2019 2:27 PM

Yes, but only slightly.

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PWSlack
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#10
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Re: Eccentric Reducer as Compared to Concentric Reducer

09/09/2019 8:41 AM

...because the effect is usually swamped by other factors.

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lyn
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#2

Re: Eccentric Reducer as Compared to Concentric Reducer

09/07/2019 5:06 PM

Eccentric reducer - Wikipedia

Concentric reducer - Wikipedia

I agree with Tornado, negligible difference, but each has its own place.
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SolarEagle
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#3

Re: Eccentric Reducer as Compared to Concentric Reducer

09/07/2019 7:19 PM

The pressure drops because the pipe is expanding...

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SolarEagle
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#4
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Re: Eccentric Reducer as Compared to Concentric Reducer

09/07/2019 8:52 PM

...at least this is true if the velocity remains the same....

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Relativity PL
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#5

Re: Eccentric Reducer as Compared to Concentric Reducer

09/07/2019 11:02 PM

This article
http://www.scielo.org.za/pdf/jsaice/v56n3/08.pdf
explains how the pressure drop in eccentric reducers is rotationally related to the reducer geometry, while the pressure drop in concentric reducers is independent of the rotational position.

In an eccentric reducer, there can be quite a large difference between the measured straight-line pressure drop, and the measured eccentric-side pressure drop, sometimes causing separation, cavitation and other flow-asymmetry troubles that interfere with downstream equipment like pumps.

Rough surface finish of the reducer's internal surface can magnify that difference, so it's wise to be aware of the initial surface finish, watching out for roughening due to reducer corrosion, or related build-up of solid impurities from the flow.

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The Prof
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#6
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Re: Eccentric Reducer as Compared to Concentric Reducer

09/08/2019 7:44 AM

Good answer. If the question does relate to pumps then I would always consider eccentric reducers. For end suction pumps flat on top and for vertical inline pumps flat on bottom.

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#7
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Re: Eccentric Reducer as Compared to Concentric Reducer

09/08/2019 8:02 AM

Superlative article; thanks.

For some time I have figured that gradual-taper reducers would be better than the usual choices. I have heard of them being called "trumpet" reducers, but I don't how readily available they are.

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Relativity PL
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#8
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Re: Eccentric Reducer as Compared to Concentric Reducer

09/08/2019 6:17 PM

The concrete pumping industry uses trumpet reducers, often elastomer lined. The bouncy lining layer returns aggressive particle energy to the particle, instead of suffering abrasive wear of the liner.

You will also find trumpet reducers throughout the paper industry, where they offer longer life despite the abrasive pulp medium.
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SolarEagle
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#9

Re: Eccentric Reducer as Compared to Concentric Reducer

09/08/2019 9:02 PM

The length of the fitting is a critical factor....

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lyn (1); PWSlack (1); Relativity PL (2); SolarEagle (3); The Prof (1); Tornado (2)

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