Eccentric Reducer - Reciprocating Pump Suction

Flat side up, to prevent the accumulation of vapor pockets in the suction.

Thanks for your response Tornado. Is your above response taking into consideration that my question is strictly for Reciprocating Pump and NOT Centrifugal Pump?

That (recip vs centrif) doesn't matter. (And why should it?)

(In certain rather uncommon cases, a vertical down-flow suction may turn horizontal to enter a pump, with a flat-bottom eccentric reducer being the better choice.)

I would tend to stick with Tornado's recommendation of flat side up for general applications. We don't know the suction piping layout, whether it has an immediate vertical run down into an elbow just preceding the reducer or whether it is coming up from down below or whether there is a long straight horizontal run into the suction. We don't know the methanol's pumping temperature nor the NPSHA at that point. Since a PD pump can pull quite a vacuum could there be vaporization of the methanol at the suction? In that case the eccentric side up could create a vapor pocket just prior to the pump inlet. Although it would affect the NPSHA, consideration to moving the reducer upstream and using a straight run of the reduced pipe size could be looked into since the recip can generally pull a good lift.

Since methanol provides little lubricity due do its low viscosity you should consider the use of specifically designed pumps for methanol pumping along with a careful review of the sealing design. A gear pump probably should only be considered if it is of the external gear driven design so the internal gears do not rely on the methanol to provide lubrication of the pumping gears.

Why we need eccentric reducer at suction side of a pump?

See this CR4 Thread: http://cr4.globalspec.com/thread/26422/eccentric-reducer#comment278069