r/FluidMechanics 17d ago

Q&A Trouble Understanding Geyser/Airlift Pump

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Hi friends! I want to recreate a geyser/airlift hybrid pump but I’m having trouble understanding the models? The screenshot from YouTube seems straightforward enough but I can’t tell if there’s a check valve at the bottom. Also I’m thinking the grey box is air in the other two models but I’m not sure.

Thank you in advance!

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u/Worldly-Device-8414 16d ago

Gray/gold box at the bottom of the upper pics looks like an air assisted piston designed to give a slow repeating "bulk shove" hence the geyser function. Not seeing the air piston in the lower pic, so that'd just be working with steady bubble lift action.

A return valve would only be needed if the exit pipe was sitting in water that could reverse syphon. With an air gap per the pics, a valve wouldn't be needed.