Hey guys and or gals, I had thought of using steam but the air was more easily available. May do it yet if I can talk my boss around to putting in the connections. The original idea came from the PM Shopnotes 1921 pg 3491,probably find it on Google. Another thing I can try is high pressure water,available at about 1000 psi. Of course with air I know when I'm done pumping out.  I'm  well aware of eductors used for bilge pumping, spent a few decades at sea. Found out the hard way to leave the hatch open when sucking out the bilge in an enclosed space. A new,properly designed one is not in the cards, hmmm maybe if I could get a hold of an old Pemberton.   As for air lifts, yes not particularly efficient, depends on free air and height of surface above air nozzle. Best I've heard of is around 65% efficiency. However they do work well enough to help. Anyhoo, thanks for the comments and ideas. 
 

The tricky part in design is matching the size and divergence of the exit nozzle with the divergence of the jet. If the exit nozzle is too large you get backflow around the Suber-water pump jet. If too small you get back pressure from the restriction. A converging/diverging nozzle is more accommodating of changes it jet shape. The jet shape will change with the amount of fluid it entrains. Entrainment flow rate will depend on inlet and outlet restrictions as well as nozzle shape. I've used water hose nozzles to make some very effective eductors. Straight pipe will not make an efficient jet pump.

2011-08-22

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