Sciencemadness Discussion Board

Condenser pump

Copper - 12-12-2015 at 01:43

People have said that they use pond pumps to power the condenser water-jacket, however I don't know how the tube would attach to the pump (the pump hole seems way too large for the tube).

See picture at


j_sum1 - 12-12-2015 at 02:25

That one might be a bit small. I had to buy a larger one because the el-cheapo I bought just didn't raise enough pressure.

Attaching a hose? Maybe a hose clamp? Or cable ties. Teflon tape if needed.

Oolong - 12-12-2015 at 04:17

I bought one that looks very similar to the one in your picture and it came with interchangeable attachments for different size tubing. The place I bought it from specified what sizes of tubing could be used with it. I use an 8mm attachment with a little bit a padding/tape to get a tight fit. I have not tested this one with my condenser yet though.

[Edited on 12-12-2015 by Oolong]

CIMG2386.JPG - 1.9MB

ave369 - 12-12-2015 at 04:25

I have a one-pump-fits-all. I've bought a garden sprinkler with a hand pump, reversed the polarity on it so it would create negative pressure, and use it to suck water through my Liebig. The same pump is used for Buchner and Schott funnels.

[Edited on 12-12-2015 by ave369]

szuko03 - 12-12-2015 at 07:05

I used a pump like that and the opening happened to be an 1in so i got a PVC reducing pipe from lowes/home depot and that just so happened to be the exact size to tape an elmer's glue bottle cap with a small opening for the glue to come out of. So I effectively lowered the opening on my pump from 1in to 6mm, small enough for the rubber tubing.

Someday i will post a picture lol its actually quite the master piece and it functions perfectly and at the time when i bough the aquarium pump i thought i would never figure it out. Get creative and you can do it.

subsecret - 12-12-2015 at 15:13

You can use a small pump as long as you get the condenser/tubing filled with water. This way, the pump really won't be raising water to any height at all; it'll just be pushing it through the tubing.

chemrox - 12-12-2015 at 16:45

Quote: Originally posted by Copper  
People have said that they use pond pumps to power the condenser water-jacket, however I don't know how the tube would attach to the pump (the pump hole seems way too large for the tube).

See picture at


Think-word: adapter

Chemist_Cup_Noodles - 14-12-2015 at 10:29

I'm not too sure you need a pump at all. I've seen people attach an adapter to a faucet so that they can connect their inlet hose to it and get water flowing through. I'm not sure how good the flow rate would be compared to a pump, and it would push water through instead of pulling it out, but it should still work. I'm not an expert on condensers so if I am wrong please correct me.

Detonationology - 14-12-2015 at 11:43

You are correct, and this method is quite common, yet also painfully wasteful for most distillations. Generally speaking, most distillations can last between 1-3 hours, which would be an absurdly long time to leave the faucet running for (my parents bitch even if I leave it for longer than a minute). For most situations, a pond rescirculator is the best bet, especially for distillations of highly volatile solvents (i.e. DCM) because the temperature of the condenser can be made very cold to maximize yield using ice cubes in the pump bucket.

[Edited on 12-14-2015 by Detonationology]

zenosx - 21-12-2015 at 21:15

My pump also seemed to be too large, however, the pump I purchased for whatever reason came with an attachment that easily fit into my 1/4" tubing, and with some zip ties it has lasted about 3 years so far...

Even without the attachments, it doesn't take much effort to make one for 1/4" tubing.

[Edited on 22-12-2015 by zenosx]

User123 - 21-12-2015 at 23:15

A nice makeshift way of having a running water source is to use two aspirator bottles:
Connect the bottom outlet of each to the attachments on your condenser, then fill one of them up with enough cold water so that it does not overflow.
To get the water 'running', you simply have to raise the full bottle higher than the empty one (i.e. to a shelf above your apparatus), and the action of gravity will cause the water to run through your condenser, and fill up the lower one.
To continue the flow, you simply have to swap the positions of the bottles, and the water flows in the opposite direction.
I used this setup for many years when I did experiments in my shed, with no access to running water.
You can add a Hoffmann clamp to the tubing to adjust the flow rate.
If the water heats up too much, you can simply pour it out of the bottom one whilst in use, and replace it with fresh cold water from a plastic bottle.
It costs nothing, saves water, and is efficient enough even for prolonged distillations over the course of hours.
Now that I have a better lab I still use the same setup, only now I use 25 litre Jerrycans instead of aspirator bottles, so that I have to swap them over less often.

Go with a pump if you prefer, I just wanted to mention an efficient and free alternative.

[Edited on 22-12-2015 by User123]

ParadoxChem126 - 22-12-2015 at 02:13

For years I've used an 80 GPH fountain pump submersed in a styrofoam cooler filled with ice water. The pump pushes water up the condenser and the water flows back to the cooler via another tube. This works fairly well for most purposes.

For extreme cases, a magnetically coupled pump can be used to pump much colder coolants (e.g. dry ice in alcohol).