Ok, since I made that post, I had a brainstorm come through...
using the bulb, I think, is about half stupid. I can accomplish it better I think, with a diaphram. It will give me more flexibility in my design as I will be able to increase diameter and therefore reduce required throw, and still...
First, I realize that magnetism does not conform easily to simple, exact, equation-driven answers, but I only need a ball-park.
I have a design for something in my head, somewhat a kin to a human heart. It will need to pump air or liquid. Not much, and a little less pressure than a siphon or...