Where can I get an.. aspirator?

[FadeToBlackened]

The things that use water to create suction..? Nothing is coming up on eBay so how much should I expect to pay for one?

[KidCurry]

Don't you have access to a tap with running water?
If not, then create an vacuum station using an pump that circulates water.
Check out this page for more details: http://www.rhodium.ws/chemistry/equipment/aspirator.html

Edit: I might have misunderstood your question, after all I'm god damn tired right now. I'll leave it anyway, since it's still unclear for me what you're after. :D

[xyz]

He's after the actual aspirator bit that uses the water to create the vacuum. He is not after a source of running water.:)

[Tuatara]

Why not make one? I did - just a few bits of copper pipe, a couple of coins for end plates, 15 minutes work with a soldering iron and you've got your very own DIY aspirator! Before you ask, the one I made works very well.

Alternately, if you're not going to put anything nasty through it, salvage the compressor from an old fridge. Mine does double duty as both vacuum pump for plasma experiments and compressor for my air-brush

[jfk]

BUY an aspirator are you CRAZY ?

ive never seen one being sold........ive made a few though

water-------------------------------------------------------------->
.................................................. ..|
.................................................. ..|
.................................................. ..|
.................................................. ..V
................................................FL ASK/FUNNEL


(ignore the ........ , the "|" is the pipe going to your flask, buchner funnel or what ever)

[xyz]

So an aspirator is just a T junction in the tubing? I always assumed that they had something special inside them to create the vacuum from the water flow. Then again, I have only seen them in pictures and have never used one.

[KidCurry]

Oh, now I see. :D
Well, you can buy one (they are cheap, and hook up to your normal watertap) or make one yourself like previous posters said.
Personally I would spend my money on one, instead of spending it on material to build one (but that of course depends if you already have the equipment needed...). :)

[Tuatara]

xyz, the 'special something' just a constriction to form a faster water jet. Helps the water entrain air bubbles.


water in

| |
| |
|---| |---|
| | | |
| \ / |
| -----
| ----- Vacuum
| |
\ /
\ /
\ /
\ /
\ /
| |
| |

water + air out



You could also make one from an irrigation T joint, they cost about a buck!

[FadeToBlackened]

interesting.. thanks for the info. I was wondering if it wasn't just a T thing. hehe

[xyz]

Thanks for explaining how they work Tuatara, I may make one soon.

[imported_reodor_felgen]

I've been wondering for quite some time now, what my best bet for a vacum source would be,
and after reading this thread I was really encouraged to make an aspirator by myself.
This is what I used:

-A 1/2 litre bottle (later cut in half)
-2 nails (ca. 8 cm)
-The end part of an old pen. Don't know how to describe this better. You could of course
use something similiar. The important thing is that you find something small that fits
in your tube, and is shaped like a cone. It's the blue part on my drawing.
-Lots of silicon and tape.

I even made a drawing of my construction, althoug I'm not sure how much that will help you,
'cause drawings has never been my strongest side. It's important to make all the seals air-tight. Mine are not, but it works anyway (would of course work better if the seals were
air-tight). Also, remember to put one of the tubes (the one at the bottom of my drawing)
into some water, or else it won't work. Tape the nails really tight to the tubes, and make
sure the "little-cone-thingy" has its nose a little bit down the next tube. Hope this helps
those who didn't already know this.

EDIT: Sorry, thought I could save the drawing as an attachment, but I was wrong. Since I don't have FTP access I can't upload it, but if you are really interested I can E-mail the drawing to you.

[10fingers]

You can buy an aspirator from any place that sells chem/lab supplies. They cost from $10.00 to $15.00. The one I have can pull about 22 in. of vacuum, but the vacuum you get will depend on your water pressure and how cold the water is. If you have a well pump for your household water supply then the water pressure will fluctuate as the pump turns on and off. This can cause problems with water being pulled into your distillation apparatus. You will need to install a one way valve in the vacuum line between the aspirator and your distillation apparatus. You can get these at pet stores, they're used for aquariums.
Aspirators are perfect for distilling acid.

[Unknown]

FadeToBlackened - In the military (U.S. atleast) they use very large aspirators called eductors that utilize the venturi principle. If you do a search on the venturi principle or eductors you could probably learn to make one yourself. Basically water is channeled through an opening that goes from large to small and there is a hole towards the smaller end on the sidewall which the water (or liquid) passes over and creates a vacuum. IIRC, the whole in which the vacuum is created is canted at a certain angle. On a side note, in the military, we had "perri-Jet" eductors. We used to tell the girls at the bars that we were pilots and we flew "perri-jets".

[blindreeper]

Unless I'm missing somthing here what it stopping the water going into your flask?

[KidCurry]

There's really no risk, but to be extra careful use an watertrap and ALWAYS disconnect the hose BEFORE turning of the water.

[blindreeper]

Again, excuse my ignorence but what is a water trap?
From my understanding a aspirator is just this:


-------------------------------------------------
---------------water goes here------>
--------------------| |---------------
************* | |
************* | ^ |
************* | | |
|
|
Vacuum is created here

Sorry for the bad pic it's my first ever attempt but I hope you can understand my concept. I know this is 99% chance of being wrong but anyways.

EDIT: Ignore the *'s they are just there so the pic works

[Arthis]

your system should be like that: image ! (http://membres.lycos.fr/arthis00000/vacuum system.GIF)

The water can't get in the tube, and it makes vacuum as the molec. of air are aspired by the flush of water. This system cannot makes much vacuum, but it still can be useful.

[FadeToBlackened]

I forget whose it is (Bernoulli maybe?), but theres some principle that says higher velocity fluids exert less pressure outward, so when the water is forced through a smaller area, it pushes forward more and outward less, that's probably why water doesn't just go through the tube. But a water trap does make sense.. in case something does go awry.

Edit: just a thought, making one of these out of a power washer could prove interesting :)

[blindreeper]

Ahhhh now I get it, thanks Arthis. These could be improvised very well indeed, and with that light bulb distillation setup you may be on your way to some very high conc. nitric in no time. Oh the possibilities...

[Arthis]

Yu must take care of the fact that the vacuum made with such a system is not very high. But this should lower the boiling point of NA (for example) enough to make the distillation easy.

The vacuum is provoqued by the flush of water and as a consequence the faster the flush the lower the pressure. Make the calculus: you have the difference of pressure that acts up, the flush of water that make a force down, and the kinetic energy is square of the speed, at a given flow. So the force is easily got by derivating that energy. But to rapid flush may be hard to handle, increases risks, etc.

[VX]

The main use of the water trap is to stop water being sucked into the receiving flask after the distillation has finished.

When you turn off the water supply to the aspirator, it still has water in the pipes, but no fast flow so the vacuum is not being produced anymore, however, their is still a vacuum in the distillation apparatus (or whatever) and this vacuum sucks the water out of the aspirator pipes and into the distillation setup. This is why a water trap is used.

Their is ways around the problem, like disconnecting the distillation setup from the aspirator before turning off the water, or by turning off the water slowly etc, but it is standard practice in a lab to fit a water trap.

[Arthis]

A trap should be used anyway, imagine some water getting into your freshly vacuum distilled NA ! You can deal with the problem without a trap if you connect a bulb between the pomp and the distillation setup, as it exists on pipets (? right name ?) to avoid you to get some chemicals in the mouth or in the squeezer.

[Tuatara]

Ahh, yes. I made that mistake once (and only once!) - filled the jar I had a nice arc going in. End of fun for that day. Vacuum limit relates to the vapour pressure of the water you use, so colder is better. Otherwise all that happens is the water boils at the low pressure point and no more gas gets sucked out of your aparatus.

Bernoulli's equation: pressure energy + kinetic energy + potential (height) energy = constant
(for an incompressible frictionless fluid, along a single streamline, under steady flow conditions)

Too bloody hard to type the actual equation here.

[Chade]

The simplest aspirator in the world:
http://sciguy.com/Experiments/AtHome/HomeExperiment.asp?Experiment=8
Warning, only to be attempted by those aged 5 and above. :)

Place a drinking straw in a liquid and blow at right angles across the top. You can also use a second straw to direct your air stream across the exact opening of the straw. The liquid gets sucked up, and then blown all over the place in a fine mist.

Any set up that has fast flowing fluid over a T-junction will work. Everything else is just tweaking the design. A narrower internal diameter T-junction increases the flow velocity across the opening, and so increases the suction. The fluid used for suction does not flow back into your system, as it'd have to make a sudden change in direction to do so and that'd only happen with wider diameters of pipe, slower flowing water, or suction from that tube. Minimise these to increase your aspirator suction pressure.

Some of the other designs, particularly Tuataras, are improvements on this, that are still just as easy to make with everyday materials.