Today’s piece of engineering excitement: progressive cavity pumps!

Progressive cavity pumps have a helical rotor and a stator with a helical cavity. The phases of the helices are different, and that somehow makes geometric magic happen such that little pockets are created in the pump and get pushed from one end to the other. The geometry also works out such that there’s a line seal from one end of the pump to the other, so there’s (theoretically) no possibility of back-flow.

Seepex, one of a handful of progressive cavity pump manufacturers, has an animation that explains roughly how these pumps operate.

Progressive cavity pumps are really handy when you need to pump really viscous stuff at very controlled rates. I gather that they’re used a lot in the food service industry for things like pumping dough and in the chemical industry for pumping adhesives and urethanes. It seems that they’re also becoming increasingly common for bioethanol sorts of things in the renewable energy world, too.

It’s cool stuff. Bear these in mind the next time you need to pump ultra-viscous liquids/slurries in a highly controlled sort of way, as I’m sure everybody does every few nevers.