Is there anyway to get a hard vacuum using chemicals? / Chemistry / Forums

Forums

4hv.org :: Forums :: Chemistry

« Previous topic | Next topic »

Is there anyway to get a hard vacuum using chemicals?

1 2 3 next

Move Thread

LAN_403

Nah

Wed Sept 14 2011, 07:17PM

Registered Member #3567 Joined: Mon Jan 03 2011, 10:49PM
Location: USA, 1960s
Posts: 260

I am doing reasearch in a device I plan to use in places where power is not located. Because I can't run a vacuum pump, is there any mix of chemicals that would absorb air down to around 35 micron? If this is not possible using cheap chemicals (it won't be useful to poor people if it costs 1,000) is there another way? The vacuum does not have to last, a period of maybe 5-10 minutes would be good.

I'm kindof cheeting here, if I don't get an answer, I'll have to spend hours in books instead at the telly :)

Conundrum

Wed Sept 14 2011, 07:22PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4059

Does drilling a hole in an old TV tube anode cap (soft copper), attaching hose and connecting to the chamber count?

Not using power is a pain, what about a wind up pump?

-A

Ash Small

Wed Sept 14 2011, 08:39PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Have you considered zeolites?

There are various 'molecular sieve' systems in use that don't require a diffusion or turbo pump, but they still require some form of roughing pump.

I'll try and find some links later.

magnet18

Thu Sept 15 2011, 03:25AM

Registered Member #3766 Joined: Sun Mar 20 2011, 05:39AM
Location:

Posts: 624

Solar Panels or a wind powered pump?
or bike power?
I don't think there are any chemicals that can do that.

Bored Chemist

Sat Sept 17 2011, 01:09PM

Registered Member #193 Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022

Sort of.

Also, you could flush the air out with CO2 then connect the chamber to a container of Na2O.
I's not easy, but it's possible.
The trouble is, if they can afford that, they can afford a diesel driven pump.

Ash Small

Sun Sept 18 2011, 03:06AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

I found a link to zeolite molecular traps, as promised:

I'm not sure if it will be usable in your application, but it does demonstrate that you can achieve a hard vacuum using chemicals.

(A similar mechanism is also used in oxygen concentrators, where zeolites that specifically absorb nitrogen are used to increase the oxygen concentration in air. These have two chambers which are used and 'flushed' alternately (usually every 22 seconds))

Bored Chemist

Sun Sept 18 2011, 09:47AM

Registered Member #193 Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022

Zeolite traps are fine, if you have a vacuum pump to revive them and access to liquid nitrogen to cool them.
I suspect those criteria will not apply in this case.

Incidentally, since about 1% of the air is argon which can not be removed chemically, the simple answer to the OP is "no".

Ash Small

Sun Sept 18 2011, 10:22AM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Bored Chemist wrote ...

Zeolite traps are fine, if you have a vacuum pump to revive them and access to liquid nitrogen to cool them.
I suspect those criteria will not apply in this case.

There was no mention of these requirements in the several threads on other forums where people have put this into practice.

While a foreline pump of some description is required, the zeolites can apparently be revived by baking.

I'll try to find those old threads (it's a couple of years since I read them)

Bored Chemist wrote ...

Incidentally, since about 1% of the air is argon which can not be removed chemically, the simple answer to the OP is "no".

I've not seen this mentioned elsewhere, but I assume you are correct.

That would imply that the zeolite trap (molecular sieve) would still be able to significantly increase the vacuum over and above whatever 'crude foreline pump' could be fashioned 'in the field'.

Nah

Sun Sept 18 2011, 03:26PM

Registered Member #3567 Joined: Mon Jan 03 2011, 10:49PM
Location: USA, 1960s
Posts: 260

hmm....

I like the trap idea, and I think liquid nitro is around the cost of soda. I think it is good because the trap is disposible, after you bake it at 300 C, you put it in the socket, you use it for around 30 minutes, and you throw it away, right?

Ash, do you mind if you post those links?

Thanks!

Paul

Ash Small

Sun Sept 18 2011, 03:41PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

Nah wrote ...

I think it is good because the trap is disposible, after you bake it at 300 C, you put it in the socket, you use it for around 30 minutes, and you throw it away, right?

The idea is that it is re-usable, you bake it, use it, bake it, use it............

Nah wrote ...

Ash, do you mind if you post those links?

Thanks!

I'll see what I can do.....

1 2 3 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob