Re: Eccentric Reducers on Pump Suctions Redux - FOT/FOB

From: <VAIBHAV_DEVDHAR@ril.com>
Date: Fri Feb 25 2005 - 23:16:00 EST

In practice we have never seen a pump suction reducer as FOB though the suction line is coming from the top in most cases in a refinery/process plant. So as per your mail below if FOB is acceptable then we have to rethink about the pump suction routing philosophy. So can you please explain the reason why FOB is also recommended.

Also could you explain the 5D straight length requirement in the Pump suction line and the potential problems in case it is not followed.

Regards


Vaibhav Devdhar
#11058
FDC-PIPING
REAL, JAMNAGAR 
                       "Jacques
                       Chaurette"                To:      
<PipingDesign@yahoogroups.com>
                       <jchaurette@fluide        cc:       (bcc: VAIBHAV
DEVDHAR/JAMNAGAR/RIL)
                       design.com>               Subject:  Re: [PipingDesign]
Eccentric Reducers on Pump Suctions Redux -    FOT/FOB
                                           Importance: Normal  Sender's OU:
Reliance |------------------|
                       02/26/05 07:56 AM
| [ ] Confidential |
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                       PipingDesign

The Pump Handbook actually recommends both situations, depends on whether the fluid is coming horizontal or from the bottom (FOT) or if it is coming from the top (FOB).

Jacques
www.fluidedesign.com

   These two sites contradict each other; McNally Institute says FOT at    pump suction and The Pump Handbook (via Fluide Design) says it should be    FOB. Any comments out there? Could the Pump Handbook actually be wrong?

   http://www.mcnallyinstitute.com/CDweb/p-html/p015.htm

   "Make sure eccentric reducers are not installed upside down at the pump    suction. The top of the reducer should go straight into the suction flange."

   "Use eccentric reducers rather than concentric reducers at the pump    suction. Concentric reducers will trap air. Be sure the eccentric    reducer is not installed up side down."

   "Be careful to install the eccentric reducer with the straight side up    to prevent trapping air at the pump suction."

   http://www.fluidedesign.com/download-free/guidel_pump_syst-extract.pdf

   "Always use an eccentric reducer at the pump suction when a pipe size    transition is
   required. Put the flat on top when the fluid is coming from below or    straight (see
   Figure 1) and the flat on the bottom when the fluid is coming from the    top. This will
   avoid an air pocket at the pump suction and allow air to be evacuated."

   [This text is followed by a graphic showing a *flat-on-bottom* eccentric    reducer directly connected to a pump suction with suction line coming in    from the top (as if feeding the pump from a piperack). The image is    credited to "The Pump Handbook published by McGraw-Hill.]


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[Non-text portions of this message have been removed] Received on Fri Feb 25 23:16:00 2005

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