Laboratory glass condensers. Friedrich

Trueblue · Post by **Trueblue** » Sun Feb 05, 2006 11:17 pm

Anyone here ever use a borosilicate (Pyrex) Friedrich condenser and have any comments on it? I'm a 100% novice and really like the looks of this thing. Am I barking up the wrong tree completely or on to better separation and efficiency? I'm pretty sure that I would want to incorporate some copper into this thing which looks quite possible, and digital thermometer placement seems like it should be easy enough when combined with a collection tube through a rubber bung in the collection outlet.

I have not seen one first hand. Only pictures.

Anyone know of any better lab glass condensers for ethanol production? Looking at this one is just my first night's bit of side research into these things.

Allen

linw · Post by **linw** » Mon Feb 06, 2006 12:58 am

Why would you want to spend over $US150 for something that was delicate and not as efficient as a $10 coper job? Nah, go for a copper coil in a copper jacket like 99% of the rest of us.

junkyard dawg · Post by **junkyard dawg** » Mon Feb 06, 2006 7:04 am

Like linw said, Copper is more suited to what we're doing here... most glass condensors are small. They are fine for small lab setups but not for adding to the end of your prized whiskey still. Besides, making copper coils is fun

Trueblue · Post by **Trueblue** » Mon Feb 06, 2006 9:17 am

I hadn't considered spending anywhere near $150.00 for one. They first caught my eye because you can find them pretty easily for under $20.00. Check eBay for instance. I live near several large universities so I've got other sources too. I'm also not looking to make a large unit but a small stove top one instead. Purity of a single run is more important to me than speed. I also just like glass. I understand the need for copper in the vapor trail and that appears to be possible to add in.

Purity with these looks easy enough. If it would be way too slow however I won't bother trying one. I'm not dead set on one. Only interested.

Anyone know approx ml/hour that could be expected?

Thanks,

Allen.

The Chemist · Post by **The Chemist** » Mon Feb 06, 2006 11:36 am

Friedrich's condensers are quite efficient, but it sounds to me like your trying to use it for something it's not designed for. The type of condenser you use has nothing to do with the purity you will get, or the efficiency of separation. This happens in the reflux portion of the column. Better to stick with the easy copper condenser. (They DO look cool, though!!)

Trueblue · Post by **Trueblue** » Mon Feb 06, 2006 12:00 pm

The type of condenser you use has nothing to do with the purity you will get, or the efficiency of separation.

The Friedrich condenser is a refluxing condenser. How would it not effect purity and efficiency of separation? It has a smaller surface area but much more efficient cooling than most refluxing still columns that I have seen. It appears to me that cooling flow could be adjusted to allow almost any reflux ratio that is desired up to a certain point of heat input.

The Chemist · Post by **The Chemist** » Mon Feb 06, 2006 12:41 pm

The Friedrich's condenser IS a reflux condenser, but you're going to run into a world of trouble trying to use it to control reflux for distillation. It's a type of what is known as a "cold-finger" condenser, and is used primarily for closed system (vacuum, inert atmosphere) applications. I would be very suspicious of it's efficiency for a reflux seperation.

Mon Feb 06, 2006 12:41 pm

"A reflux condensor can be anything which represents no or almost no resistance to the gases"
I found this on a lab equipment forum. From what I gathered, a reflux condenser has nothing to do with the amount of reflux taking place, just the ability to cool the vapor without creating pressure in the column.

It is pretty cool looking, though.

Are you making a small pot still, or are you going for something with a reflux coumn? Either way, it might work, as long as you aren't trying to push large amount of vapor through it too fast. I don't know enough about it to say for sure, though.

Trueblue · Post by **Trueblue** » Mon Feb 06, 2006 1:23 pm

Perhaps I'm looking at this device bass ackwards.

My thinking was to pack the open area with copper mesh or chips held in by mesh plugs. Hooking up water lines with a valve control for flow rate of ice water. Plugging the top side opening with a rubber stopper fitted with a thermometer and line to a final condenser. Fitting the bottom vertical opening to the lid of a stock pot or similar and allowing the vapor to enter the condenser from the bottom and hopefully reflux before passing on to a final condenser through the rubber stopper at the top.

Maybe that will clarify my intentions a bit though futile they may very well be for all I know.

Here is a good example of the exact style that I'm thinking of. It's a coil type instead of a bulb type.

http://cgi.ebay.com/Reflux-condenser-Fr ... dZViewItem

The Chemist · Post by **The Chemist** » Mon Feb 06, 2006 1:40 pm

Who knows, it may work. Seems like a lot of fuss to have a cool looking reflux column (basically what it would be in your configuration). Let us know how it turns out!

The e-bay one is a standard type Friedrich's, that part that looks like a coil in the picture is a spiral molded into the "cold-finger", or "bulb" as you call it. The ones with a true coil inside are Graham condensers.

Trueblue · Post by **Trueblue** » Mon Feb 06, 2006 2:07 pm

I'll be sure to post back if I try it out. I must admit that I am intrigued by the glass factor. I like watching things work. The compactness is interesting to me as well.

Trueblue · Post by **Trueblue** » Mon Feb 06, 2006 11:54 pm

Using these condensers for our normal purpose probably isn't productive enough I'm guessing by now.

A glass still sure is pretty though. I put this one together in my mind for about 250.00 USD for new, of the shelf, in stock items. Including the stand and clamps to hold it together.

http://home.earthlink.net/~allensfilesu ... oject4.jpg" onclick="window.open(this.href);return false;" rel="nofollow

B and F should have individual control of cooling flow.

It may not produce a lot but it seems to me that it would produce the highest possible purity?

I don't foresee it as an efficient production apparatus but perhaps a great experimental model.

For $250 or maybe even less, I might just be willing to buy the parts and play with it.

Gotta have yer toys.

Allen

The Chemist · Post by **The Chemist** » Tue Feb 07, 2006 8:50 am

Certainly looks cool, but a couple of observations:

1. For the reflux column, a Graham condenser will require a lot more energy input than you really need. It's a very efficient condenser, and to overcome the thermal mass of the water you'll need a lot of heat. To regulate the flow of new water into the condenser will be really tricky, and you'll have a good bit of really hot water just sitting in there. A better idea would be to go with a plain fractionating column filled with Raschig rings, or some equivalent material.

2. You could save a bit by eliminating the connector at "C" unless you don't have space, and need the condenser pointed downward.

3. The Allihn condenser isn't terribly efficient pointed downward. Depending on how you feel about 1 and 2 above, replace the Allihn with the Graham if you want to maintain the downward position of the condenser, or change the orientation to 20 deg downward and keep the Allihn.

Glass still are SO cool!!!

Trueblue · Post by **Trueblue** » Tue Feb 07, 2006 9:11 am

Thanks for the tips Chemist. That all makes good sense. I do like the idea of having the condenser pointing down and there was only about $10 cost difference between that and several other types including a Graham. I'll probably take your advice and change both condenser types if I do put this thing together. There is so much to choose from out there when it comes to glass. Pretty neat. You can put together almost anything that you dream up. If I find a surplus shop around here that I can walk in I'll be like a kid with some fancy Lego's. lol Gets expensive quick though and right now I need some stuff for a "real" still so it will have to wait a bit.

Allen