VACUME CHAMBER

[Conway StevensParticipant]

Yes do use safety glasses. In fact I would have recommended to use even thicker material. I use 1/2 and 3/4 inch thick Lexan/acrylic when I vacuum process my propellants and even then I end up with more or close to 3/8 inch deflection in the surface. Im running at 28″ and with 5cfm down to 40 microns.. So it can be scary. Just be careful.

BTW each of the missile works stuff is all calibrated by vacuum chamber. In fact a very expensive highly accurate 100,000 ft + capable one.

DUDE, Way beond what im doing! Although I thought 1/2″ would have been better! Especially since we cant get that transparent aluminum from Star trek 4 yet. I dont even know what a micron is!

Scotte 🙂

For what I use it for its to pull as much as possible of the air that has been induced into the propellant when I mix it. Its done this way so I can achieve a better propellant with higher density and more uniform consistency throughout the propellant. A micron is as Bruce states 1,000,000th of a meter. Its a value for me thats important as it will tell me what the smallest particle i can pull out via the vacuum pumps capability. The smaller that number the better. My next pump will be able to pull down to 20 micron.

But what you have going for your project sounds pretty cool. Great way to see if your matches are working.

BTW Bruce I just about had to get up off the floor with that very small Moron bit. Thanks for the laugh.

[SCOTT EVANS]

Are you sure thats what a Micron is? That would mean every one in Battlestar Galactica was very very tiny. Even Lorne Greene! They would never get to earth, at the rate they would have been traveling! So when the cylons were 500,000 Microns away, and closing, they were only half a meter?

Conway
I would like to see one of your vacume chambers some time. I bet your pumps are alot more expensive than mine. 29 inches probly is 100,000 feet or so.

Scott e

[Warren B. MusselmanModerator]

Indeed, the micron is 1 millionth of a meter and was originally called the micrometer. (See millimeter, centimeter, decimeter, etc. etc.)

However, I think it popular culture making it a millionth of a moron at least is a helluva lot funnier. I almost choked on my coffee over that Bruce. Thanks for the chuckle.

Warren

[AdrianParticipant]

Yeah, where did you get your pump?

Santa brought me one for Christmas from Aircraft Spruce that I thought was going to suck out at least 80-90% of atmospheric pressure, but sadly it doesn’t suck that much…er… well, you get the idea. I did a test and it was only able to simulate an altitude of 12k ASL (6k AGL), which is better than 3k from a shop vac, but not worth $300, since it’s also rather slow. I’m a little skeptical about its ability to remove bubbles from vacuum layups at that rate, even though that’s what it’s supposed to be for. I’d really like something good to 30k or more.

[Warren B. MusselmanModerator]

My vacuum pump pulls to 25″ Hg… don’t know what that corresponds to altitude-wise or in millibars or whatever, but it sure can pull v-bagging down tight on a lay-up.

Warren

[AdrianParticipant]

Fun google tip: Type “25 inches of mercury in Pa” in Google search (or your Google toolbar) and it will tell you the answer. I use Google now for my calculator whenever I’m at a computer. BTW, 84.6 kPa corresponds to about 36 kft ASL.

[SCOTT EVANS]

My vacuum pump pulls to 25″ Hg… don’t know what that corresponds to altitude-wise or in millibars or whatever, but it sure can pull v-bagging down tight on a lay-up.

Warren

All other things being eqaul 1″ is about 1000 feet(at our altitude anyway), give or take. Climb into an airplane at Vance brand and you will see the manifold pressure gauge sitting at 24.5-25 depending on the weather of coarse. 29.9 – 24.5 = 5.4
5400 feet. Not perfect but close. The runway down there sits at 5050.

[James Russell]

[/quote]Scott, a micron is a very small moron, or a millionth of a meter.[/quote]

Never thought you were the name calling type 😀

[AdrianParticipant]

Well, my vacuum pump really sucks after all. In a good way. It turned out that one of its fittings was loose, so once I fixed that, it really pulled it down hard. It inverted the lid of the rubbermaid container I was playing with at about 36,000 feet equivalent which opened the edge seal. Then I tried it again with a spacer to keep the lid from getting too deformed, and it ended up shattering the rubber-edged, see-thru lid. Yikes! Just before it went, the mechanical pressure gage on the pump was reading 21″ of mercury, which (since we only have about 24″ of Hg to start with) means it had about 60kft equivalent.

The larger altitude chamber I’ve been using for the calibrations will clearly need to be beefed up. It’s about a foot on a side, with 3/4″ plywood walls and a see-through lid. But 10 psi * 144 sq inches = 1400 lbs. Hmmm.

[SCOTT EVANS]

Well, my vacuum pump really sucks after all. In a good way. It turned out that one of its fittings was loose, so once I fixed that, it really pulled it down hard. It inverted the lid of the rubbermaid container I was playing with at about 36,000 feet equivalent which opened the edge seal. Then I tried it again with a spacer to keep the lid from getting too deformed, and it ended up shattering the rubber-edged, see-thru lid. Yikes! Just before it went, the mechanical pressure gage on the pump was reading 21″ of mercury, which (since we only have about 24″ of Hg to start with) means it had about 60kft equivalent.

The larger altitude chamber I’ve been using for the calibrations will clearly need to be beefed up. It’s about a foot on a side, with 3/4″ plywood walls and a see-through lid. But 10 psi * 144 sq inches = 1400 lbs. Hmmm.

I think I might have vacume chamber ENVY!!!!!!!!!!!!
I might have to get some of that lexan and a new pump!!!
Adrian your vacume setup SUCKS! 😉

Scott e

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