Draw Line Sumps

[TankDude]

API 650 provides recommended draw line/sump size combinations but doesn't really elaborate on how these were derived. I understand that the sump should be of adequate depth to prevent the suction line from pulling air out of the tank, however, can anyone tell me of a quick way to check this or point me toward a good reference? My client is wanting to increase the diameter of a sump and reduce the depth, however the volume is also being reduced in the process. Would a vortex breaker be sufficient to handle the decreased depth?

 

[IFRs]

It is common to use shallow sumps or sumps that do not correspond with the API guidelines. Many secondary bottom retrofit installations do not cut the lower bottom for a sump and the sump must fit in the space between the bottoms. For normal water draw off function it probably does not matter. My understanding is that sumps are not used for production withdrawal or high rates on an on-going basis. I do not know of published calculations but am interested in what folks come up with here. Keep us informed please!