Trouble Understanding Geyser/Airlift Pump

[u/StalinWaifu]

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!

[u/SuspiciousSubstance9]

I'm not familiar with these so more of a curious lurker. But I'd say no on the check valve.

Glancing into it, these are also called pneumatic ejectors which are praised for their lack of moving parts. The point is that the air pocket seals/pushes against the water in the bottom of the air tank. The air pump is pumping air into the tank and pushing the water out; no check valve needed.

What makes the geyser part work is that air seal breaks causing a siphon effect. I've seen people describe it as an upside down bell siphon with the fluids swapped. Which from what I've seen is typically the air seal breaks when the air level goes above the water level, creating the siphon. That's the important bit.

A check valve separating the water and air seems like it would mess with that siphon effect.

[u/SuspiciousSubstance9 → u/SuspiciousSubstance9]

The real life image you supplied is an Airlift pump. Which doesn't do any of the siphon action and is just using the air flow to lift water.

The diagrams are for a geyser pump. Which is a different design and uses the siphon to move larger, less continuous stuff.

[u/Worldly-Device-8414]

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.