Will a Sprengel Pump Work?

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Rich Feldman
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Re: Will a Sprengel Pump Work?

Post by Rich Feldman » Fri Nov 17, 2017 12:22 am

Yes, and Sprengel pumps were superseded by diffusion pumps driven by boiling mercury.

In the 1960's, Scientific American's classic Amateur Scientist columns had several projects for skilled, well-equipped amateur glassblowers.
Including a Hg-vapor diffusion pump.

I couldn't immediately find a picture of that, but here's a contemporary glass diffusion pump you can buy from svpneon.com.
StandardDP.jpg

Here's one homebrew Sprengel pump running on youtube.
https://youtu.be/viJ3T-1KZqY?t=641
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Re: Will a Sprengel Pump Work?

Post by Silviu Tamasdan » Fri Nov 17, 2017 3:26 am

That's the same video I linked to earlier in the thread. Cody has several other interesting videos, including running a mercury still. Somehow he manages to do it safely without exposing himself too much to mercury (another video has his own toxicology test results for heavy metals in the body including mercury and lead).
There _is_ madness to my method.

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Re: Will a Sprengel Pump Work?

Post by Rich Feldman » Sat Nov 18, 2017 6:17 pm

Silviu did post that video link first, and I'm sorry not to have noticed sooner.

Here's my account of cleaning "dirty" mercury, obtained through craigslist from a local resident about 5 years ago. Since then the street price has gone way up. I think after a USA-and-Europe export ban, to discourage unhealthy and wasteful use by very poor people extracting gold in far-away countries.

Looks like some previous owner had been collecting Hg metal from various sources. Floor sweepings? Came to me in a factory-printed "Mercury, 10 lbs" bottle (about the size of a 12 oz soda can), mostly full. I bet the shrink seal on its cap was put on to discourage friends or children from playing with it.

It looked too scummy to behave well in glass capillary tubes, such as McLeod gauges. I found online links to many references, dating back more than a century, about cleaning and purifying mercury. Bet it still deserves the title "the purest metal" in commerce.

I cleaned about a pound of mercury by shaking, in a thick plastic bottle with corrugated sides and stoutly-threaded screw cap. Starting with soapy water or ammonia, then vinegar, maybe even dilute HCl, till the wash water was clear. The metal looked mirror-clean after that, and "pinholing" (look it up). I never made it fall in fine drops through a tall column of dilute nitric acid, nor distilled any under vacuum. (Hulett's method mitigates the problem of dissolved zinc coming over with the Hg.) Nor, yet, has any of my mercury entered a McLeod gauge, or even a thick-walled glass capillary tube procured for resistivity measurement.

Mercury is traded and priced by the 76-pound iron flask (since 19th century) and by the metric ton.
flasks.jpg
Who wants to compute the size of a metric ton, in a cylinder whose height and diameter are the same?
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Silviu Tamasdan
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Re: Will a Sprengel Pump Work?

Post by Silviu Tamasdan » Sat Nov 18, 2017 9:04 pm

1t=1000000g; divided by 13.53g/cm3 makes 73909.83cm3. V=pi*r^2*h; if h=d=2r, then V=pi*r^2*r/2=(pi*r^3)/2
r^3=2*V/pi, solve for V=73909.53, r=36.1cm or d=h=72.2cm.
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Re: Will a Sprengel Pump Work?

Post by Rex Allers » Sun Nov 19, 2017 2:05 am

I think you made a mistake. You said
h=d=2r
but then you substituted r/2 for h
seems correct formula should be
r^3=V/(2*pi)
giving
d=h=45.5 cm
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Rich Feldman
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Re: Will a Sprengel Pump Work?

Post by Rich Feldman » Sun Nov 19, 2017 2:05 am

Silviu Tamasdan wrote:
Sat Nov 18, 2017 9:04 pm
1t=1000000g; divided by 13.53g/cm3 makes 73909.83cm3. V=pi*r^2*h; if h=d=2r, then V=pi*r^2*r/2=(pi*r^3)/2
r^3=2*V/pi, solve for V=73909.53, r=36.1cm or d=h=72.2cm.
Is that your final answer? :-)
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Re: Will a Sprengel Pump Work?

Post by Rex Allers » Sun Nov 19, 2017 9:11 am

Rich,

Dang, even knowing what I was looking for, it took several tries on searches to find that container diagram. Nice work to find that.

Did you choose to ignore the correction I made for Silviu's simple mistake? His calculation seems right except for when he ignored his own value for h when he substituted.

From container dimensions: 508 - 2*10 = 488 mm = 48.8 cm
My corrected value was 45.5

If you are building a container, better to spec it a little big.

Hg ton contain.png
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Dennis P Brown
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Re: Will a Sprengel Pump Work?

Post by Dennis P Brown » Sun Nov 19, 2017 1:43 pm

Yes, a long detailed series of posts on this thread relative to Hg and its distillation and or/availability and weight/volume; uh, why again, one asks? Are we getting to be a Hg forum? ;)

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Re: Will a Sprengel Pump Work?

Post by Silviu Tamasdan » Sun Nov 19, 2017 2:54 pm

LOL that is why I usually triple-check my calculations. I didn't for this one. :)

And I feel that discussions of Hg in a vacuum subforum are A-OK. Hg is a useful metal if used wisely. Unfortunately I don't have any.
There _is_ madness to my method.

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Re: Will a Sprengel Pump Work?

Post by Rich Feldman » Sun Nov 19, 2017 6:28 pm

Rex, I think we both hit Send at about the same time. I wasn't responding to your answer. Didn't figure it out myself, or find that dimensioned diagram, until seeing the first answer (which is correct size for 4 metric tons).

The most recent round is doubly relevant at fusor.net. The big boys at Oak Ridge N. L. investigated mercury storage in preparation for their Spallation Neutron Source. Most productive in the world, excluding nuclear fission reactors. A search for ornl spallation will do. My initial search was metric ton mercury container.

The 76-pound "flask" unit of measurement probably dates to long before the 19th century. I bet it's connected to an early Spanish or even Roman unit for commerce, used long ago around the Almaden mines in Spain.
https://minerals.usgs.gov/mineralofthemonth/mercury.pdf
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