Sciencemadness Discussion Board

Aspirator/Water outlet for home

dumbsnake - 20-4-2007 at 17:10

Hey all,

I have lurked a bit and I really like this forum. I finally gave in and bought a bunch of glassware. Unfortunately I don't have one of those chem lab water spigots. I'd like to get something so that I can hook up my distillation setup. Also, I need to get an aspirator. I've been searching around and everywhere I find they are selling products that I can't hook up to my faucet at home. I spent about an hour at the hardware store trying to figure out a possibliity here. What have you all done? Thanks for any help.

Magpie - 20-4-2007 at 17:17

Are you trying to connect to a standard US kitchen sink with aerator?

dumbsnake - 20-4-2007 at 17:27

That is what I have, but I took off the aerator and measured it and everything. I'm open to any ideas that could work. My sink head is 13/16" with 27 thread.

[Edited on 20-4-2007 by dumbsnake]

The_Davster - 20-4-2007 at 17:31

I have one that looks like the one on wikipedia, or at least in terms of connections.

It does not fit to standard faucet screw threads, so I brought the aspirator to home depot and asked the guy in home depot's plumbing section to help me get all the connectors to connect it to my tap. He found all necessary connectors within 40s or so.

Magpie - 20-4-2007 at 17:32

This is from an earlier post of mine:


I use a kitchen sink tap with internal (female) threads. I bought a chrome plated brass aereator with the same thread size (only male), gutted it, and soldered my brass aspirator to it.

The soldering is a little tricky, but it worked.

bio2 - 20-4-2007 at 17:44

If you can't readily find the adapter parts just use a
piece of plastic tubing secured with 2 hose clamps.

Magpie - 20-4-2007 at 18:56

Here's a photo of the adaptor I made using an aereator and a brass 1/2" x 3/8" coupling, pipe threads. As you can see the soldering job is crude. But it is watertight and worked just fine. Aspirators come with 3/8" male pipe threads in my experience.

adaptor.jpg - 73kB

kaviaari - 20-4-2007 at 23:10

The easiest way of dealing with this is to take a rubber stopper and some glass tubing. Fit the stopper with about 5cm of glasss tubing snugly to the faucet and that's it. When using aspirator I fit the in-end of the aspirator to another stopper and secure it to the faucet with clamp.

Barbed Connector

MadHatter - 21-4-2007 at 17:48

Magpie soldered his own pieces together and made a connector. I found a combination
of parts and Home Depot that ends up at a barbed connector off my faucet. It just
took some searching and some Teflon tape to make a working arrangement.

chemrox - 21-4-2007 at 20:22

you can go over the faucet with plastic tubing and a hose clamp. Then over the aspirator with tubing and another hose clamp. You can get a lab type faucet .. ie one with a high curve at home depot for under $60. And while you're there you could shop for connecting hardware to go to the inside female threads in the faucet. Finally, I had an apsirator that was designed for emptying water beds and was made to hook to an outside faucet. This worked well on laundy sinks and may still be available.


visitation123 - 26-4-2007 at 11:05

water aspirators using faucets as you call them in your part of the world is a waste of water, forgetting the hassles required to connect it.

Why don't you focus your efforts on building an aspirator station? All your missing is a pond pump.

See here:

chemrox - 27-4-2007 at 02:05

or buy a vacuum pump on ebay of labx for less than the cost of one of these time and space consuming projects

Vacuum Pump

MadHatter - 27-4-2007 at 20:04

I have a vacuum pump but there's no way in hell I'm going to use it for nitric acid vacuum
distillation. My glass aspirator is used for that purpose.

visitation123 - 29-4-2007 at 07:31

Exactly, without modification the aspirator passes distillates directly into solution.

uchiacon - 27-8-2009 at 21:17

However a vacuum pump can go far below an aspirator, and if you can get one cheaply (under $100) it might be best to use that with a vapour trap yes? 10torr or less for nitric distilatin would mean that it'd boil at a very low temp.

kclo4 - 27-8-2009 at 23:33

The aspirator I've acquired I got to hook directly to my hose outside. I've then attached a long tube into my work place.

I have a several aspirators that are stuck onto the faucets they've been connected to for probably 50 years. I also have one other set up that can also connect to the hose. As for the sinks I don't know if they are standard sinks, and the aspirators are attached in a weird way but if that is of any interest to you we could make a trade or something. PM if you want I guess.

Phosphor-ing - 28-8-2009 at 05:39

In the US this is a quite affordable option.

uchiacon - 31-8-2009 at 23:06

I think I might try to design my own aspirator, although my limited means may cause some problems. I found a good book named "organic chem lab survival guide" by James Zubrick. It has some good diagrams in it for the aspirator, vapour traps etc.

So, lets say I have a slightly smaller inlet tube flowing into a slightly large T joint with the adjecent part with a hose barb for a vacuum tube. So theres still a tiny gap between the water flowing through the T joint and the T joint itself. So I'd assume that the tiny gap would allow the venturi effect and it would work. And is it best to have the outlet tapering in or out? I will probably find it hard to make a tapered outlet, but just in case, which is better?

Alternatively, a T joint with an icing nozzle in it( I think this was discussed somewhere) which would be similiar to this diagram.
The icing nozzle would be better than just a smaller tube going into a larger one I presume? More pressure = bigger vacuum?

Oh, and a last thing, lab aspirators will always outperform home made ones right? I might be able to get a metal one from the uni, but I'll try and make this one anyway.

air_tech_drawing_big.gif - 27kB

kclo4 - 1-9-2009 at 05:19

I remember frogfot's website had a nice DIY aspirator, does anyone happen to have his pages saved? His site has unfortunately gone under, I've been looking for an archive of it for a while, I haven't search to hard, but I haven't had much luck.

Klute - 1-9-2009 at 07:24

I really don't think it worth the hassle of buikding your own aspirator.. it's the kind of thing you are better off just buying, they are cheap and relatively availble.. Very precise measure are required to get a decent vacuum, not just any T shaped plumbing will do the trick..

Once you have that piece, construction a aspirator station is pretty simple and cheap, and saves alot of water, and able sone to neutralize any fumes that are trapped int he water. Just add some Na2CO3 to the water and a smalll amount of TCCA or similar to avoid rusting and molding/rotting of the wtaer (thanks to Bio for this tip). Always worked wonders for me, get routine 25mmHg with cold water with a teflon aspiratoir that cost me 20e..

uchiacon - 1-9-2009 at 19:42

What did visitation say about a pond pump?
My pump is rated for 30 PSI at 46L/min, I guess I just have to sell it and buy a less powerful one then.

Any suggestions for a low L/min pump with high PSI?

I saw somebody had a 120PSI pump with a 5L/min flow rate on trademe...

Would a beverage pump work? or would it cough out after a bit? Coz all these pond pumps seem to be A. submersible and B. not high enough pressure.

[Edited on 04-07-09 by uchiacon]

[Edited on 04-07-09 by uchiacon]

Contrabasso - 6-9-2009 at 02:41

There is a UK lab supplier doing a polypropylene filter pump for about £12 and a couple of other filter pumps in different materials for lots more money. Does anyone have a UK supplier for a glass filter pump?

I too do not want to pull 99% nitric through a mechanical pump with pump oil!

I wondered whether the V2O5 process for H2S04 could be driven by a filter pump pulling the SO3 into recirculating dilute acid.

Inoxia - 6-9-2009 at 04:01

To recirculate the dilute (and eventually conc) acid you would need a completly corrosion proof pump because otherwise it would get attacked by the acid.

watson.fawkes - 6-9-2009 at 05:58

Quote: Originally posted by Contrabasso  
I wondered whether the V2O5 process for H2S04 could be driven by a filter pump pulling the SO3 into recirculating dilute acid.
You don't want to be dissolving SO3 directly in anything like a dilute solution. That reaction is violently exothermic, which is why in a commercial plant they dissolve it in concentrated acid. The now-even-more concentrated acid is diluted (again exothermic) elsewhere, again where they can manage the heat release.

not_important - 6-9-2009 at 18:59

It's not just the exothermic nature, it's that the SO3 tends to form fine droplets of H2SO4 that are difficult to collect or absorb into dilute acid or water, but concentrated H2SO4 absorbs the SO3 without the formation of droplets. With diluted acid the SO3 is in part reacting with the water vapour, that's the source of the fine droplets; acid of a high enough concentration has very little water vapour over it.

watson.fawkes - 7-9-2009 at 04:38

Quote: Originally posted by not_important  
It's not just the exothermic nature, it's that the SO3 tends to form fine droplets of H2SO4 that are difficult to collect or absorb into dilute acid or water[...]
Yes. There are any number of reasons not to use dilute water. My immediate concern in explanation was to point out that absorption in dilute water would likely melt a small filter pump.

james1956 - 1-10-2009 at 11:31

i took a brass firehose nozzle [ about 6''] that fits on a garden hose, drilled a 1/4" dia. hole at a 45 degree angle. inserted a slightly curved piece of 1/4" copper, soldered it in. put a 3' piece of galv. steel pipe with a 90 and a valve , put in a tote filled with water. works great.

entropy51 - 1-10-2009 at 12:11

Welcome james 1956. That was a good year (I can sort of remember it.)

You made an aspirator and it worked on the first try? Impressive. I tried to make one a time or two, gave up and bought one.

elementcollector1 - 6-10-2013 at 20:00

I can't seem to get my aspirator to work. I've plugged it in the right way, with a garden-hose brass barb connector (same as you'd find on the average condenser), but no matter how high I turn the water up, the filter doesn't run any faster. Does anyone know why this is? My guess is that I need a larger diameter input of water (i.e. not using the barb, but rather connecting to the hose directly somehow).

bfesser - 7-10-2013 at 08:24

In my experience, a filter will only run so fast, no matter how hard a vacuum you apply. What make/model of aspirator are you using? Have you taken a pressure reading on your water supply?

MichiganMadScientist - 7-10-2013 at 15:44

My following suggestions are very half-assed, but in the absence of other options, they work:

If you need vacuum, you can purchase a hand pump vacuum brake bleeder system from your local auto parts store. It will produce enough vacuum for vacuum filtration, and even for Some vacuum distillation applications.

If you need a water aspirator to circulate water through a condenser, a simple siphon getup should work.

Again, these are desperate measures, but they work if your lab happens to be located in a room with no plumbing..

elementcollector1 - 7-10-2013 at 15:52

I guess I'll go to the hardware store and see if they can get me a brass fitting that connects to the aspirator itself.
Hand pumps, as I've been told, are faulty and unreliable. Not sure why.
My lab is located in the garage, and it's easy to run a hose around through the garage door. Where's yours, MMS?

bfesser - 7-10-2013 at 15:54

Quote: Originally posted by bfesser  
What make/model of aspirator are you using? Have you taken a pressure reading on your water supply?
No answers?

elementcollector1 - 7-10-2013 at 16:06

Quote: Originally posted by bfesser  
Quote: Originally posted by bfesser  
What make/model of aspirator are you using? Have you taken a pressure reading on your water supply?
No answers?

My mistake, forgot about that part. Model is, as I can tell, Bel-Art Scienceware #329470000 (bought here:

Now, the next thing I should do is figure out the hose size and tank pressure, to determine the maximum pressure this is capable of putting out.
(What I should really do is buy a strong water pump...)

bfesser - 7-10-2013 at 16:11

Do you have a gauge to test your household water pressure? (0 – 40 psi / 275.8 kPa)

elementcollector1 - 7-10-2013 at 19:07

Parents claim 60 psi, which doesn't seem right. Is there a standard for American households?

elementcollector1 - 16-4-2014 at 16:55

Heh. Evidently, I am an idiot when it comes to vacuum testing. I had recently bought an aquarium pump which claimed 110 GPH, and for all I know lives up to the claim. However, upon attaching to the aspirator, it failed to do anything. My setup for testing vacuum was simple: A pear-shaped flask with one 14/20 joint and one glass tube (for hose connections). The tube was connected by vinyl tubing to the aspirator outlet. The 14/20 joint was connected to a vacuum gauge I had bought in the same order (which is strangely stuck at ~5 in. Hg). The fit between the gauge and the ground glass joint was a little loose, so I used tape (such scientific apparatus!) to fix that. The apparatus was for all intents and purposes air- and water-tight. Worked perfectly. Upon testing with the aquarium pump, the needle never even moved.

Upon testing with the garden hose outlet (which I had earlier discarded as being 'too weak', due to the fact that my finger wasn't being sucked inside when I blocked the outlet), the vacuum pulled was at least 25 in. Hg! I was hesitant to try further, as I might either break the gauge or the glassware (it's ChemLab brand, if I recall, bought from Dr. Bob a while back). The gauge was maxed out at 25 in. Hg due to the +5 reading mentioned earlier, so I'm not sure what it would do. If about 30 in. Hg is absolute vacuum, I might actually fix the gauge by pulling it past maximum, as when the vacuum was broken the gauge would just drop back down accordingly.

Sorry for the confused jumble of thoughts, I just wanted to report the success with the garden hose to those of us who are interested in home vacuum.

Dr.Bob - 16-4-2014 at 18:12

Just a note, most water aspirators have a built in ball check valve, that tries to prevents water from being sucked into the vacuum line, but they are notorious for getting stuck, so often just shaking the thing until you hear the ball rattling inside is all that it takes. Or, if you have clogged the poor things with sludge, some of them can be taken apart and the valve space cleaned with a q-tip or cotton swab or needle. PS, I recently found a brand new plastic aspirator from Nalgene that looks just like the one in element collector1's post, they are decent, but maybe not the best ones ever made, I personally prefer the metal ones, but they corrode easily. It would be $5 plus postage if anyone wants one.

And normal water pressures in the USA range from 40 (very low side) to over 100 psi (quite high, but ideal for showers) so the 60-80 would be pretty normal. Many new houses have pressure regulators built in, along with one way check valves, which can lower the pressure, too much in some cases.

[Edited on 17-4-2014 by Dr.Bob]

elementcollector1 - 16-4-2014 at 21:25

Incidentally, what vacuum does yours pull? The product specifications on mine state a maximum of 27.4 in. Hg (found here).

Dr.Bob - 17-4-2014 at 06:16

I don;t know what this one pulls, as it is new, so I have not used it. I use them at work, and they routinely pull down to something in that range, but giving a maximum of 27.4 seems overly precise, since the vacuum will depend on water pressure, flow, and temp, as well as the tubing used. I almost never use a water aspirator for anything that requires any precision, as they cannot provide a steady vacuum. I use them for filtering and evacuating larger flasks to purge with N2, but for anything critical, even the rotovap, I use a diaphragm pump or rotary pump, as they provide a steady rate, those can get down to 15-30 mtorr or so for rotary, the diapharm one gets in the 100 mtorr range, but the gauge is not very accurate.

Few vacuum pump gauges are very good, other than very nice ones. I have tested many against each other, and rarely get similar readings that are within the specs given in the manual. As soon as they are used once, they start getting dirty, corroded, and less accurate. But they work for most purposes, and most are precise enough for the job.