Sciencemadness Discussion Board

Using a pump as an aspirator driver

User - 25-5-2009 at 04:07

Well I could not find a topic about this so please tell me if this is already been treat.

Well my idea is to use a pump that is supposed to be used for artificial pools/pond's (or how ever it would be called in English :P).
These pumps pump dirty water or are used to spray up water.

I already use one for cooling of set-ups in combination with a 65 liter cement mix bucket.

I can imagine that when these pumps are let to a smaller tube there could be quite some power.
Which might be used for creating a vacuum.

The advantage would be that one is not flushing 100's of litres right down the drain (which is a shame).
Besides one could control the flow with a simple power regulator.

Anyone any ideas/experience with this ?

hissingnoise - 25-5-2009 at 06:36

IIRC, there was a thread on this some time ago. . .
In most ways it is superior to mains-driven aspirators.
If the set-up is used for vacuum distillation, the reservoir temp. can increase as the distillation continues and cooling may be necessary.
Tossing ice cubes in may be enough, and the bigger the tank reservoir the better.
A powerful pump will produce a high vacuum without worry of pressure fluctuations. . .
If you're distilling acids, a small amount of base in the tank will neutralise acid vapours.

chemrox - 25-5-2009 at 13:13

Did you do a search for "aspirator?" I did and limited it to the last six months. The result was about a page full of threads. Here's one: http://www.sciencemadness.org/talk/viewthread.php?tid=12030#...

The device you're trying to build exists as an "Aspirator Pump." I bought one on ebay for less than $50. It consists of a tank, pump and two aspirators. I recycle my condenser cooling water through the tank if I'm using it. Sometimes I add ice to the bath.

[Edited on 26-5-2009 by chemrox]

User - 25-5-2009 at 13:23

Yes did that search and could not really find answers.
Maybe I did not look carefully enough, in that case my apologies.
Can you tell me the speed of your pump?
So i might have an indication of what pumps i should look for.

hissingnoise - 25-5-2009 at 14:10

Chemrox, that link wasn't of any use to User.
User, use your existing pump to see how well it works and use the biggest tank you can get.
You'll need to devise a way of preventing air bubbles from the high-pressure stream from the pump-outlet getting into the inlet as this will severely affect pulling power.
Done right, the set-up will give a high, reliable vacuum without the worry of corrosive vapours attacking a dedicated vacuum-pump. . .

Jor - 25-5-2009 at 14:14

Very interesting. Soon I will buy an aspirator, but cannot attach it to the tap-water, as my tap is not suitbale for it.
So I am definately interested. How much water would have to pass through the aspirator per minute for a good vaccuum for filtering and sucking dry?
I gues sthis would be best expressed as amount of water per minute per cm2.

hissingnoise - 25-5-2009 at 14:37

Using a pump-driven aspirator for forced filtering would be overkill, IMO---it would be simpler/cheaper to adapt or replace your existing mains tap.
A pump-driven aspirator is ideal where a lot of vacuum distillation is intended. . .

DJF90 - 25-5-2009 at 14:51

hissingnoise: Vacuum filtration can be done using the same vacuum source as vacuum distillation, as this generally tends to be sufficient for both applications, being in the range of 100-500 torr. "Vacuum" distillations are rarely (in my experience) done in a vacuum, but rather under reduced pressure.

chemrox - 25-5-2009 at 21:50

You guys are demonstrating the danger of assumptions. I'm running my stills at 6 mm down to 0.3 mm for most operations. There are a few distillations that can be run at the water pump. Mostly I use the water pump for flash evaporation and filtration. I have no idea what rate my pump runs at. It uses about a third cubic foot of water. Trying to make one of these, I think you'll spend a lot, have a gawdawful big machine and one that doesn't work very well. The kind of pump you'd use for moving water through your condensers is different than the circulating type built in to the aspirator pump. The aspirator pump I bought occupies a volume a bit less than a small milk carton crate. In addition to the different pump sizes and configurations there are also different aspirator through puts. I have three sizes of them; on in plated brass and nickel, one in glass and a couple of Nalgene ones.

stoichiometric_steve - 27-5-2009 at 14:02

and it is generally a better idea to get a cheap diaphragm 2-stage pump on ebay, because it pulls reliable vacuum and uses much less electrical power.

User - 27-5-2009 at 15:34

Yeah well although reliability is an important factor.
The thing is that it would be nice to have something that is able to pull vacuum build from scratch and the aspirator that is laying around anyway.
I don't expect super performance.

The main point would be if it is even possible to make this of practical use.
Not to pull super high vacuums, normal aspirators wouldn't anyway.
The reason would be that my lab is quite far away from the closest tap point, and even if I would stretch this using garden hose I still wont have a drain.

Btw the pump I am using right now for cooling does not seem to suck through air bubbles.
I believe this isn't happening because the suction and the return are both under liquid.

chemrox - 27-5-2009 at 22:18

http://cgi.ebay.com/Cole-Parmer-7049-00-VACUUM-Aspirator-Pum...

Make this guy an offer. I got one just like it for $75. It works better than anything you can make and takes up less space as well. Trying to build one would be pure vanity given the availability of these. I can even give you a copy of the manual..

User - 27-5-2009 at 23:44

Well maybe your right , its cheap.
Hehe thnx. :)
Where i live this stuff starts around 150 euro's.
And i would indeed have to let it ship from the USA.
The price differences are just huge.
But like around 100 dollars for just shipping is scary.

[Edited on 28-5-2009 by User]

User - 20-12-2009 at 06:29

Yeah well iam digging this up to give a update to what i tested.
I was rerouting my waterpump leads and happend to see some piece that exactly fitted my aspirator.
After some screwing around with hdpe tape the make the damn thing waterproof I turned on my pump.

Surprisingly it atcually pulled some sucktion , not much.
Still it would like to see to get some performance out.
The construction was very simple : pump went into the aspirator and the end connected to a hose went back to the bath.
I thought the hose going back to the bath could be the problem so i started fooling around.
I shortend the hose at the end to approx 10cm, this improved the pull significantly.
The aspirator even pulled more vacuum with a small piece of hose than without.
Quite surprising.

Well i have a single stage pump so this is not really of any importance to me but I am saying that it is quite possible to get some vacuum out of a setup like this.

Panache - 20-12-2009 at 17:54

Also the back pressure created by aspirators really reduces the lie of your pump, easily to use the tap!!

But seriously a good alternative to using your vac pump to strip solvents and filtering is to get a reasonably large cylinder from a scrap yard. Pull a vacuum on this using your vac pump, then use this vacuum 'reservoir' to strip solvents and filtrations, just be careful with leaks as it will get frustrating quickly otherwise.

User

DetaDude - 24-12-2009 at 17:29

I use a set (2) of pumps to drive six (6) aspirators, and can pull down a vacuum of 29.5 in.Hg. , B-4 this setup I used a 3 aspirator unit and could do the same number but now I can handle a greater volume.

My pumps came from Harbor Freight for approx. $30.00 ea. and I use two twenty gallon plastic tubs plumbed together,, one I fill with ice water the drain back side the other the suction side I fill with clear fresh tap water. The system works flawlessly and gives me the flexibility of however many pumps or aspirators I may need.

aonomus - 24-12-2009 at 18:54

Detadude: can you link the particular pump that you are using? I'm looking for a pump that would work for an aspirator, or at least for a reference point in terms of size...

DetaDude - 26-12-2009 at 22:18

aonomus:

Send me a U2U.

DD

User - 27-12-2009 at 05:40

DetaDude

Could you post a picture of your setup.
Iam quite interested .

Panache - 31-12-2009 at 09:46

Quote: Originally posted by DetaDude  
I use a set (2) of pumps to drive six (6) aspirators, and can pull down a vacuum of 29.5 in.Hg. , B-4 this setup I used a 3 aspirator unit and could do the same number but now I can handle a greater volume.

My pumps came from Harbor Freight for approx. $30.00 ea. and I use two twenty gallon plastic tubs plumbed together,, one I fill with ice water the drain back side the other the suction side I fill with clear fresh tap water. The system works flawlessly and gives me the flexibility of however many pumps or aspirators I may need.


Do you run the aspirators in parallel or in series, so to speak?