VHS-4 Diffusion Pump

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Taylor_Romain
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Real name: Taylor Romain

VHS-4 Diffusion Pump

Post by Taylor_Romain »

Hello Good Morning,

"The fusioneer need never purchase a diff pump of more than 4" in diameter with 2 or 3 inches diameter being ideal." [1]

For a diffusion pump the recommended diameter is 2in-4in as stated above however I've purchased a Varian VHS-4 that has a 8in inlet that will be reduced to 2.75in by a reducer. Will this be overkill working with a 2.75in 6way chamber?


[1]
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Taylor_Romain
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Re: VHS-4 Diffusion Pump

Post by Taylor_Romain »

Images:
pump2.png
pumpp.png
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Emma Black
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Re: VHS-4 Diffusion Pump

Post by Emma Black »

This is the same size pump as the one I'm using and got for free. Its very much more than you need for the size of chamber. It will work but need lots of oil, a very big backing pump and lots electricity and cooling.

For operating mine I run it at 240v to first bring the chamber down to pressure but while operating I switch it over to 110v which reduces the heating power, you could also use a dimmer.
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Richard Hull
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Re: VHS-4 Diffusion Pump

Post by Richard Hull »

When doing that original FAQ info, I was thinking about what Emma just noted. Giant pumps will mean giant oil bills. As you will learn, this oil ain't motor oil, but a special oil that is not cheap! So far as I am concerned, if you have the money to blow on oil and the adapter needed to shrink the giant throat down to a more normal 2.75 conflat, by all means, go ahead. Emma's pump was free.....I hope your pump was free, too. That way all the money saved on such a large pump will need to be used to buy oil and suitable adaptation to a small fusor system.

On a small fusor system, a 3" throat diff pump will do as well as a 15 inch throat pump. The general rule is the pump throat should scale with the chamber size/volume. Especially if you are buying everything new in box. However, deals and freebies of bigger stuff can break such rules as long as the cost of breaking the rules doesn't break your bank in extra expenses.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
John Futter
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Re: VHS-4 Diffusion Pump

Post by John Futter »

taylor
check out aliexpress / alibaba
there is dow corning 704 , 705 variants /clones that the chinese make that are about US100 a quart

https://www.alibaba.com/product-detail/ ... 728aHSzJnw

is an example
and another but spend is US$1000 approx for 25 litres
https://www.alibaba.com/product-detail/ ... 2d69cmROgN
but you will buy a lifetime supply or you could supply other members on this site
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Dennis P Brown
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Re: VHS-4 Diffusion Pump

Post by Dennis P Brown »

Do realise a throttling valve for the diffusion pump is required to prevent massive deuterium gas flow for large diffusion pumps. One needs to hold the deuterium pressure in the chamber from 5 to 25 microns (chamber size dependent.)
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