Reducer at pump suction

From: <BANI>
Date: Thu Feb 21 2008 - 21:53:00 EST

Piping Handbook, Second edition (Igor J. Karassik, and Others) in Chapter 12, Installation, Operation and Maintenance suggests that if the source of water is from the top, the flat side of the eccentric reducer will be at the bottom. But if water flows up, from below, the flat side shall be located on the top.

   The same reference also suggests that if the change in diameter is more than 4 inches, rather the concentric reducer should be used with proper venting arrangements. In such cases eccentric reducer may lead to flow disturbances.

   This practice is generally followed in my company.

   Regards,

   Bani K. Mitra
   02/21/2008

"Noakes, Kevin (Calgary)" <kevin.noakes@worleyparsonsmeg.com> wrote:

           Kevin Noakes,

Process Piping Consultant,

Lead Piping Designer for Worley Parsons MEG

The Mustafa Rayees question addressed:

Reduction in line size at a pump with horizontal suction connections is made with a flat top eccentric reducer when the suction line comes from below the pump centerline and a concentric reducer when the suction line comes from above the pump centerline. The reasons for this have been expressed already. As such pump suction piping should be arranged to minimize unnecessary pressure drop and vapor pockets.

Damage to a pump impeller, its balancing and the casing et. al. (performance) will also be influenced by the flow pattern of the fluid into it. The more stable and less turbulent and laminar the flow into the pump the lest impact it will have on the physical structure of a pump impeller and its rotational balanced and unbalanced forces. The length of straight suction pipe before the pump and downstream of horizontal plane elbows is usually mandated by pump manufacturer requirements or by engineered design standard, which ever is greater. The range of length of straight suction pipe before the pump requirement can vary from 2 to 10 times the pump suction diameter.

Cheers,

Kevin

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[Non-text portions of this message have been removed] Received on Thu Feb 21 21:53:00 2008