Maritime Discussion: FRESH WATER GENERATOR
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deba prasad saha
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Location: w.bengal
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Quote deba prasad saha Replybullet Topic: FRESH WATER GENERATOR
    Posted: 28 Sep 2006 at 8:16am
AS DISTILATE WATER PUMP  IN FRESH WATER GENERATOR IS CENTRIFUGAL PUMP ,REQUIRES POSITIVE SUCKTION.HOW IS IT DONE IN FRESH WATER GANERATOR,WHERE WE MAINTAIN VACUUM.
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Alok Govil
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Quote Alok Govil Replybullet Posted: 23 Oct 2006 at 6:03am
Distillate pump is usually placed in  a position where the suction has a 'head' - difference in height between condenser lowest point and the pump - this neutralizes the vacuum effect. This is the reason for drop in distillate pump efficiency if the seal is no good.
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PERI AVADHANI
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Quote PERI AVADHANI Replybullet Posted: 12 Nov 2006 at 10:49pm
Hi,
  Centrifugal pumps are inhrently not self priming, but are able to take suction.  Consider the pumps like ballast, bilge etc which are placed much above the ballast tanks but are able to take suction.
  Here the only problem with the centrifugal pumps is that they are not self priming. SO in FWG the distillate pump is placed below the datum of the condensate  collection level. Hence no problem with priming.
 
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chandrashekar krishna reddy
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Quote chandrashekar krishna reddy Replybullet Posted: 10 Dec 2006 at 10:53pm

Hello Mr. Saha,

FWG distillate pump always has some NPSH, since it is placed below the condensate water level. Problem would occur only if there is atmospheric pressure at the eye of the pump and the condensate is under vacuum. But here pressure (ie vacuum inside the shell) is same on condenste and up to pump suction (considering that the seal is in good condition). So, the pressure at the suction side of the pump is more than that of the condensate by an amount equal to its head. hense there is no problem.

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SRINIVAS ANGA
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Quote SRINIVAS ANGA Replybullet Posted: 22 Feb 2007 at 4:44am
IN FWG DISTILLATE PUMP IF THERE  A SMALL LEAK IN MECHANICAL SEAL OR GLAND PACKING IT CAN BE DEALT WITH BY DIRECTING WATER DIRECTLY WHILE STARTING, ONCE PUMP TAKES SUCTION IT CAN RUN QUITE WELL.  
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bhavik padaria
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Quote bhavik padaria Replybullet Posted: 13 Apr 2007 at 10:39pm
the centrifugal paump does not require positive suction ..
but if positive suction is provided is it is easy to overcome the force or pressure required to  deliver the  liquid.also the positive suction head  ensures that p/p is always primed ..
 
the vacuum in FWG is in the shell ...
 
the p/p is of the capacity to produce sufficient vacuum in the suction side
 
 
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