Interesting. I was thinking that the pressure drop at the nozzle exit would be higher with higher pressure upstream of the nozzle. I guess I'll have to dig out some of my old texts. Here we go, O'Rourke, "General Engineering Handbook" 1940 pg 813. To paraphrase, ejector usually uses a small quantity of the working medium at high pressure, to pump a large quantity at low pressure. Efficiencies between 15 and 30%, capacities to 700gpm. Well I don't expect I'll get anywhere near that. I'd be satisfied if I could get another 10 or 20 gpm, and stunned if I got 100gpm.
Yup, had one for years,some years back. Aaah, the memories, best dang bed I've ever had. Mine took somewhere around 1 to 2 hours to empty, probably because I had to run about 20 ft of 1/2" hose both ways to the bathroom. Size that eductor up 3 or 4 times Screw pump would probably be perfect for the sewer.  A few years back I did use a homemade jet to clean out the last inch or so of oil out of a compressor crank case, gravity drain was a bit higher than it should have been. Worked pretty well, though I did have to drape a rag over the discharge bucket, oil came out more as a mist than a stream. Took most of the sludge out too.

2011-08-22

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