Pump design with loosest tolerance?

[Jaepheth]

If I were going to build a small pump out of clear acrylic or other plastic, perhaps using non lubricated ball bearings only. What design has the fewest parts and loosest tolerances?

This is for a thought experiment. This pump would be sealed away where it would be unserviceable and pumping elemental mercury at low speed to feed a self-contained desktop fountain. (pump would be driven by a flywheel that is powered magnetically from outside the container by hand crank, like a jack-in-the-box)

I may attempt to actually build this fountain someday, but only if I'm convinced I can do so safely.

 

[Rubycon]

Mercury has a very high specific gravity of 13.546.
A peristaltic pump can handle this but its torque is going to be difficult to drive magnetically unless you use a cylinder and plug method with neodymium magnets.

Even so its output will be very pulsated and with mercury that would be as fun as it is dangerous!

 

[Jaepheth]

I wanted to use a magnetically driven flywheel so the whole fountain could be permanently sealed inside a jar without any compromising holes in the container.

 

[Rubycon]

How big is this supposed to be?

A flywheel to work with this kind of pump would be quite large. (well to work as a flywheel is supposed to work! )

 

[sjwaste]

Couldn't you just use gallium? It's more expensive, but not known to be particularly toxic, and it has about half the density as mercury.

You'd have to keep the fountain heated to close to 90F to keep the gallium liquid, but that's really not a big deal. You could just use a light bulb.

 

[Tim]

I am convinced that upon the day of humanities greatest peril, Rubycon can save us.

Anyone else with me?

 

[Jaepheth]

I was imagining something like a brass wheel about 5" in diameter and maybe 1" thick.
The whole fountain wouldn't be much larger than a peanut butter jar.



I had not considered gallium.

 

[Rubycon]

I don't think that will work as planned.

How about a more avant-garde solution using a variable pitched auger made of kynar?

 

[BarkingGhostar]

No one mentioned the reactor. Where is the reactor in this problem?

 

[Jaepheth]

I don't think that will work as planned.

How about a more avant-garde solution using a variable pitched auger made of kynar?

So.... Archimedean screw?

 

[sdifox]

Electro-Magnetic induction pump?

 

[Rubycon]

Variable pitch and larger flutes sort of like a pseudo Congreve oscillator. The surfaces need to be very slippery and absolutely inert to Hg. The Hg must be absolutely pure as if it leaves "tails" the action gets spoiled in fairly short order.

So.... Archimedean screw?