I know what you mean. The device you're referring to is a diaphragm. It usually has water on one side, and compressed air on the other. It's mostly designed to maintain a steady pressure at the faucet.
Also being an electronic guy, I agree, the cap would work, electrically.
I believe that the air pressure is important. What mostly concerns me is why you believe that this vibration comes from the pump's impeller.
I believe it to be more likely that the vibration comes from an unbalanced impeller. Did you modify it in any way? Is your rig very restrictive?
It's possible to balance an impeller, similar to RC (another hobby) airplane propellers: mount it on a shaft (perfectly perpendicular), and roll this shaft on parallel bars. See where the prop (impeller) is heavy, and shave it (sand it).
|