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Hi Everybody,

I've been working on converting an air compressor tank into a bell
chamber. I had and idea to set up the chamber horizontally because I
couldn't find a thick plate for the base. I thought I would use the
end of the tank for a door and use two angle flanges to stiffen the
cut ends of the tank and to form a sealing surface for an O-ring.
The base flange will mount to the supporting frame of the system.

As I got into working with the tank and flanges it occurred to me
that I could use the end of the tank for my base just as well in a
vertical configuration. I think I would like that better anyway as
it allows easier access to the goodies inside the chamber. The tank-
end base allows for plenty of room for mounting feedthroughs too.

If you would like to check my progress I have added a file in the
Photos section titled Homebrew High Vacuum System Roy M. I included
a cross-section sketch of the mating surfaces of my angle flange seal
idea and a photo of some of the pumps and other things collected so
far.

Comments are welcome.

Roy M.

this kind of thank are test for about 300 lb of pressure I think

bwaht a vaccum at 14 lb per inch put on
waht is the calculation of the limit

I have the same kind of project but whit pool filter thank
about 26 inch in diameter

jack 47'N 71'W

Hello Jack,

I found a formula for cylinders under external pressure in an 1947
edition of Kent's Mechanical Engineers' Handbook. It states the
collapsing pressure for thin wall steel lap-welded cylinders is:

P =1000(1-square root of 1-1600(t2/d2))

P= external collapsing pressure in pounds per square inch
t= wall thickness of chamber or cylinder
d= outer diameter of chamber or cylinder

So for my .120" wall 16" o.d. chamber we get

.120 X .120/16 X 16 = .0000562

1600 X .0000562 = .08992

1 - .08992 = .91008

square root of .91008 = .95398

1000 X (1 - .95398) = 46.02 pounds per square inch

Also, this formula is for cylinders longer than 6 tube diameters.
So for my short cylinder with a domed end and a steel flange on the
other end only 17 inches apart I think the collapsing pressure is
even higher than 46 psi. 46 psi is more than a 3X safety factor at
sea level air pressure in any case.

Try the formula on your pool filter tank and see what you get!

Good luck and thanks for the reply,

Roy M.




--- In VacuumX@..., jacques savard <jacquessavard@...>
wrote:

this kind of thank are test for about 300 lb of pressure I think

bwaht a vaccum at 14 lb per inch put on
waht is the calculation of the limit

I have the same kind of project but whit pool filter thank
about 26 inch in diameter

jack 47'N 71'W

Hi Everybody,

I've been working on converting an air compressor tank into a

bell

chamber. I had and idea to set up the chamber horizontally

because I

couldn't find a thick plate for the base. I thought I would use

the

end of the tank for a door and use two angle flanges to stiffen

the

cut ends of the tank and to form a sealing surface for an O-

ring.

The base flange will mount to the supporting frame of the system.

As I got into working with the tank and flanges it occurred to

me

that I could use the end of the tank for my base just as well in

a

vertical configuration. I think I would like that better anyway

as

it allows easier access to the goodies inside the chamber. The

tank-

end base allows for plenty of room for mounting feedthroughs too.

If you would like to check my progress I have added a file in

the

Photos section titled Homebrew High Vacuum System Roy M. I

included

a cross-section sketch of the mating surfaces of my angle flange

seal

idea and a photo of some of the pumps and other things collected

so

far.

Comments are welcome.

Roy M.


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