Help ( a vacuum thermos) for school

[LazyDave]

So for school I have to make Thermos that will not allow the temperature to drop more then 10 C. so I like to over do things so I want to make a vacuum. Since I don't have a heat stripper, (I am going to use plastic sheets of the body) I need to cut out every single panel. So I need a really good bonding material and something that will make an air tight seal that can resist a vacuum. Also I need to find some tubing, a one way valve, a release valve, a hand pump that will allow me to make a vacuum. I might be forgetting something, but I’m not sure.

 

[DarthRacer]

Use PVC pipe.

 

[LazyDave]

For what, what do you mean. Like a little one for the inner wall and the larger one for the outer? what about the top and under side. See think of a reall thermos. The inerer wall are floating in a vacuum. the only contact to the outer walls it the top. Porget the under side. (I'm a idiot, just use a cap) but still what about the top?

 

[fisherman]

hey i know what u could to you could go to walmart and buy one,lol :jk: . Sorry I'm no help and i was just messin around

 

[Rolex]

Go to Home Depot or Lowes, or whatever home supply is in your area. PVC pipe comes in many sizes, so I would suggest you get 2" for the inside chamber, and 4" for the outside. For the bottoms, you get 'end caps' and glue them in place using the pvc primer and glue. For the tops, you get the threaded adaptors, and glue them in place. Then you get the threaded caps that you can take off. Get teflon tape so you can get a good seal, and still be able to take them off.
One of my compressors works both ways, a compressor, or a vaccuum pump. Not all compressors will do that, but if you have a pipe going into it, remove the filter and get threaded adaptors that will take a 1/4" npt fitting. That's the size that you see on gas station air hoses.
Drill a hole in the outer PVC pipe, and thread and glue the 'spring lock' end in the pipe. Snap the nipple end into it, and connect the hose to the inlet of the air compressor. When both caps are on, you will create a vaccuum between the 2 chambers. You will need a valve between the 'spring lock piece and the PVC, so you can avoid losing the vaccuum when you disconnect the air line.
Kick that around for a while and let me know if you need more info.
Go to the store and take a good look at all the parts and adaptors that are available, since you now have a basic idea of what you need to do to make a thermos of sorts. Every thing you need will be in the same aisle.
Draw up roughly what you have in mind, or explain it to someone there who will be able to help you out with the parts you'll need.

 

[LazyDave]

my air compresor doesn't use spring lock conectors it screews in. In fact i tink that means i can conectit right to the valve.

is this the idea w have in both of our heads
http://nervalhi.net:8080/~dgoldber/therm.jpg

what about a sealent around the valve?

 

[Rolex]

Exactly.
Use the same sealer you used on your back plate.

 

[LazyDave]

cool. Thanx

 

[LazyDave]

sweet i got my parts. But i only have a one inch gap is that ok?

 

[Rolex]

Between the pipes? Not a problem. It's not how much vaccuum is there, just that you can keep it there. You might want to silicone a piece of foam to the bottom, then silicone the inside pipe to that to help stop the temp transfer from the outside pipe to the inside one. (Rather than directly gluing them surface to surface)

 

[LazyDave]

i don't need to do that much work.

 

[LazyDave]

so the valve has been installed and sealed. i tested the valve with the air compressor. It can hold 100 psi, but not sure if a vacuum will cause a diffrent effect. also i need a vacuum. sadly my air compresor doesn't have an air inlet. So i could use some help with that

 

[crzy-svg-usr]

r u trying to make a vacum former? if so i have made one not too hard

 

[LazyDave]

I'm trying to make a tempory vaccum, yes, in the thermos. it sould hold until valve is opend.

 

[Rolex]

Consider yourself lucky that it didn't explode with 100 psi. Air pressure is not something to mess with in a container that isn't rated for it.
I suggested earlier that you would probably need some adaptors to make an inlet for the compressor, in order to draw the vaccuum from your thermos.
Check with your teacher. If he suggested something like this, then I would think they have a vaccuum pump available. Every science class has one.
Do NOT pressurize your container again. The pressure could have blown the end caps off, or completely blown up the pipe. Vaccuum will draw them together, and you also have the advantage of 'curved surface' for strength.
If I'm correct, a vaccuum pump will only take you to a negative 32 Hg. (inches of mercury)

 

[JESSE G]

Sounds like you almost made a plastic hand gernade with that much pressure, between Rolex and your Ideas on this thermos you can start selling them and become millionares hehe, I bet you get and A++ good luck man

 

[LazyDave]

No i didn't make the container yet. No this was my idea. Also I'm not using endcaps anymore. A guty who graduated from Vt helped me. He works at ferguson. I'm not that dumb to pressureize it. I ment the valve can hold 100psi. i attached it directly to the air compresor. I will post pics as i make it.

 

[JESSE G]

Ok wasn't implying that you are dumb actually from what I have read it sound like you are very intelligent, from your post it just sounded like you had pressurized it just a misunderstanding I would like to see pics of it when your done it sounds intresting.

 

[Rolex]

Oh, okay.....Just the valve. I couldn't believe the container could hold 100 PSI, that's why I said you were lucky it didn't explode.
Anyway, go to a science room and check out a vaccuum pump to see what kind of fittings you will need to connect the pump to your thermos.

 

[LazyDave]

i don't beleave our scool has a vaccum pump. I guess i could e-mail the science and shop teachers.