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 ```I am looking for fundamental fluid mechanics equations + associated sketches to help me understand and design a subsea venturi lift eductor pump.``` Request for Question Clarification by redhoss-ga on 06 Mar 2006 05:25 PST `From what depth do you plan to pump.`
 ```Hello pierre16, I beleive that I know what you are looking for. A venturi pump uses atmospheric pressure to lift fluids and is limited to about 20 feet of lift. Here is some info to back up that statement: http://www.nciweb.net/eductors.htm What I think you need is called "air lift": http://www.globalsecurity.org/military/library/policy/army/fm/5-484/Ch4.htm Principle. Water can be readily pumped from a well (or the sea floor) using an air-lift pump. There are no air-lift pumps in the Army supply system; however, in the field, you can improvise and make a pump using compressed air and the proper piping arrangement. The assembly consists of a vertical discharge (eductor) pipe and a smaller air pipe. Both pipes are submerged in the well (or sea water) below the pumping level for about two-thirds of the pump's length. The compressed air goes through the air pipe to within a few feet of the bottom of the eductor pipe and is then released inside the eductor pipe. A mixture of air bubbles and water forms inside the eductor pipe. This mixture flows up and out the top of the eductor pipe. The pumping action that causes water to rise as long as compressed air is supplied is the difference in hydrostatic pressure inside and outside the pipe resulting from the lowered specific gravity of the mixed column of water and air bubbles. The energy operating the air lift is contained in the compressed air and released in the form of bubbles in the water. Figure 4-9 shows the operating air-lift principle. All of the formulas and charts showing submergence, air pressure/volume required, and gallons of water pumped per cubic feet of air are shown. Scroll down to the bottom of the page to find the info. This should be all that you need to size a compressor to move the volume of water you want to pump. If you have any questions, please ask for a clarification and I will help you further. Redhoss```