Sciencemadness Discussion Board

Picking the right condenser?

smaerd - 9-3-2010 at 18:04

Hello again sci madness :).

Well I'm obviously quite a noob as I've stated in just about every post now. Being a noob I need some helpful suggestions, this time about condensers.

So from what I've gathered is there are Liebig condensers and Graham condensers. These come in a variance of lengths(200mm to 500mm).

I've only personally worked with a liebig condenser before in the lab at school. I used it for distillation, which was cool.

So I know a liebig can distill and a graham can reflux. Is it possible to use a liebig to reflux, or is that not safe? If not can a graham be used for simple distillation?

Ideally I'd like to have a condenser that can handle small volume liquid distillation(250ml rbf only filled to 125ml), and small volume reflux(250ml rbf limitation again).

Any suggestion on lengths(mm) or which type of condenser might suit these needs best? If I'm missing something here, feel free to let me know ;).

edit - Also what is the name for those sink faucet to tygon tubing adapters? :P

Thanks again!

[Edited on 10-3-2010 by smaerd]

DJF90 - 9-3-2010 at 18:49

There are in fact, many more condenser types than two. However I'll keep this brief as I'm sure you're capable of finding out about the others yourself.

The liebig condenser is your "all round" condenser. It can handle most tasks you can throw at it, whether it be reflux or distillation.

The graham condenser comes in two varieties itself; coolant around the coil, and coolant through the coil. Now I cant remember much about the former, do I'll discuss the latter. This condenser style typically has more surface area than the Liebig, per unit length. As far as I am aware, it is not bad at either mode of use, but with distillation you supposedly get "creep" around the cooling coil, leading to incomplete condensation. I'm not sure how severe this is, but it can't be that bad because Buchi use a similar style in their Rotovap condensers. And of course the graham condesner is perfectly at home in reflux mode.

Other flavours you might like to look at are:
Jacketed coil
Davies double surface
Double coil
Freidrichs
Air
Ether

Typical lengths will vary with joint size, but for a B24 joint you will typically find 360mm adequate for a Liebig. 200mm may be fine for some/most applications. For more extreme cooling 450mm and 530mm are generally available options.

For a graham, I've seen 200mm and 400mm available, and maybe one in between.

I hope this was helpful to some degree.

[Edited on 10-3-2010 by DJF90]

Skyjumper - 9-3-2010 at 18:58

I wish I had a condensor that could be used as a reflux :3 My lab only has this old, old condensor (rubber stoppers hold the center tube inside the water jacket!) and from the looks of it I can't seem to figure out how to set it up as a reflux (without having a lot of leaks around the rbf to reflux connection)

mr.crow - 9-3-2010 at 18:59

I would recommend a small condenser (150mm) with a built in distillation head. This is good for small volumes.

Then a 300mm Liebig or West for large distillation or reflux.

There are a variety of reflux condensers available with a coil inside. There are a lot more expensive. You can use them for volatile solvents like ether.

Everything can be 24/40 BTW

Skyjumper - 9-3-2010 at 19:04

http://unitednuclear.com/index.php?main_page=product_info&am... 40., good all around condenser.

Remember water goes in on the bottom inlet, out at the top!

rrkss - 9-3-2010 at 19:18

Personally I use a 200 mm West (Liebig with a smaller jacket) for most of my work whether that is distillation or reflux. Just get yourself one with standardized joints and you are good to go. I like 24/40 and 19/22 joints since I don't do too much larger scale work.

smaerd - 10-3-2010 at 11:26

Thanks for all the suggestions. SkyJumper I appreciate you looking into this for me however I think I'd want a ground glass condenser.

I'm going to be performing hydrodistillation primarily for aromatics/essential oils. So far here's some plants I will be distilling: rosemary, mint, limeonene, lavender, any other fun suggestions?

DJF90 - 10-3-2010 at 12:45

I didn't know there was a plant called limeonene; surely you mean you're steam distilling limonene from orange peel?

smaerd - 10-3-2010 at 12:54

Yes yes yes, sorry lol!

Orange terpenes, weeee. I guess it can be used a solvent, a supplement, a degreaser/cleaner, etc. Figure why let those orange peels rot? :)

bbartlog - 10-3-2010 at 13:08

Unless you have industrial quantities of orange peel (or lemon peel) you won't get enough limonene to use as a solvent or cleaner. It's a relatively abundant essential oil (1% of the peel) but you'll still be looking at quantities on the order of a gram, if you're just using surplus peels from household consumption.

agorot - 10-3-2010 at 19:19

I have a 500 mm graham condenser that I use a lot among others, but the only problem I have with that one is that sometimes it is difficult for the liquid to actually get through the system. What happens is that the liquid gets pushed through the condenser until eventually the pressure on the boiling flask side cannot be increased farther by use of temperature and that pressure equals the pressure on the coolant side of the system so basically condensed fluid flow comes to a standstill. Even with a vacuum pump on the system a point is reached where I have to let air into the boiling flask side of the system. It can be quite frustrating, so I can only distill small quantities of things at a time with that particular condenser.

bbartlog - 10-3-2010 at 20:02

Yes, that's a good point. Sometimes you really want a short path condenser just because the heat losses are too hard to overcome otherwise. I have a 300mm Hempel column and even though it has no active cooling (no circulating liquid) it can still be hard to drive things through it with an oil bath (and direct flame can scorch stuff). Still if he's mainly doing steam distillation I don't know that that is such a concern.

DJF90 - 10-3-2010 at 23:10

I did a steam distillation of a quinoline the other day, and that was difficult with just the drysyn mantle (T=170*C by thermostat); I needed to use a heat gun to drive the vapour through the stillhead and into the condenser.

smaerd - 11-3-2010 at 11:25

So would a 300mm liebig be okay for steam distillation in a 250ml flask(250 limit because of my glas-col)? Would this also be sufficient for a 250ml flask for reflux?

rrkss - 12-3-2010 at 03:59

300 mm liebeg is more than enough for those tasks as long as you have a constant source of cool water circulating through it. In fact I use a 200 mm for most of the things you mention so 300 mm will be more than enough for everything except for maybe ether synthesis.

HammerOfLight - 13-3-2010 at 22:32

I have the following;
Graham Condenser
Liebig Condenser
Packed Collumn
Vigreux Column
Allihn Condenser
riedrichs condenser
I like to have all my basses covered. The other item I have involves small hollow glass balls between a reverse version of the allihn design, the act like a bubeller cap system only simpler.


DJF90 - 14-3-2010 at 11:13

For someone who likes all their bases covered, I'm suprised by the lack of an air condenser... Nice collection though!

1281371269 - 14-3-2010 at 11:36

Yes I like to have my bases covered too, I never leave the lid off the sodium hydroxide.

smaerd - 14-3-2010 at 14:09

How do you get it out then :P?