3 replies to this topic

[Zauberberg]

Good evening from Muscat,


After finding so many references related to the "flooded suction" term in process design literature, this particular subject is still not clear to me. Can somebody shed additional light in resolving this issue, regardless of the type of pump being employed in any service?

What does the term "flooded suction" mean, irrespectible of the pump type?

[Art Montemayor]

Good Evening Sylvester:

The attached workbook illustrates 3 different types of pump installations that I interpret as pumps with a "Flooded Suction". I've always dealt with the application as you see it and have never been corrected.

Stating it briefly, I would define a flooded suction as a suction pump chamber that is full of liquid due to the liquid level and pressure condition in the suction tank. Obviously, this is the best and most preferred type of pumping suction condition sought.

I hope this helps you.
 Flooded_Suction_Pumps.xls   23.5KB   303 downloads

[Zauberberg]

Thank you Mr Montemayor,

When thinking of "flooded suction" term, my first thought was - "the pump that is always primed", ie. that fluid will fill the pump casing as soon as suction gate valve is open.

By the way, which are the pumps that do not have "flooded suction"? I haven't seen such devices in downstream operations (petroleum refining) and the only thing I can remember, is one old hand-pump in my grandfather's garden which had to be "primed" with water from the top opening; otherwise there would be no water coming from the underground well, and flowers and cucumbers would probably dry off.

Thanks again,

[Art Montemayor]

Zauber:

Yes, you have hit on a very important, albeit romantic, point.

What has been done traditionally to alert all engineers - especially process design ones - is that the "flooded" pump is automatically primed and can be instrumented and controlled for automatic start/stop very easily. That is the key to it all - the elimination of the priming step. However, it does come with trade offs - such as a need to effectively block off the suction and supply efficient case drainage for inspection and maintenance.

Primining, flooded suction are important features to know about the pump application because the need/lack of priming is critical to controlling the pump and also from a safety point of view and design. For example, there can logically be no "non-flooded" Firewater Pump allowed in a process plant. To expect such a pump to be ready to pump instantaneously the moment it is required is ludicrous. Thus, such applications require fully flooded suctions.

Your grandfather had a vested advantage over my grandfather who had to rely on me to "pump" the crank on his water well winch in order to haul up buckets of water for the goats and the tomato crop. I would have given my right arm for a pump that only required priming. But then, those are memories that never go away and inspired me to seek out ways to move fluids in a more efficient manner.

Have a good day in Muscat.