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Now why did the term "static pressure" slip my mind? Thank you.
I think, instead of just saying "It ain't so!", just doing a little experiment would be enlightening.
Start your ShopVac and cover the exhaust hole. Harder to hold back the pressure than you might think. The motor slows. It's trying to force more air out the volute, is compressing denser air, but slipping.
Now cover the intake. Sucks your hand tight, and, no air to move, motor spins faster, as it's no longer doing any more work than trying to build vacuum in the tank. Again, not efficient, due to slip from clearances and impellor design.
Have to revise a post on another board, same subject but different application. Posted results there with 1 1/4 hose attached. Corrugations in the hose change things tremendously from open port.
Cheers,
George
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