Condenser question 1.5" column 3/8" tubing

[durgan]

Hello all,

I am going to make a coil condenser this weekend and my planned boka build utilizes a 1.5" diameter copper column. I was planning on using 3/8" copper tube to make the condenser. It seems that I could wind it around a pipe that has 3/4" diameter and it will fit snug. My question is would the 3/8" tubing kink too easily or even fit properly with such a tight wind and how much copper length might I need for a 5" long finished condenser?

Any help would be greatly appreciated.

durgan

[MuleKicker]

You prolly want to do it in 1/4" . 3/8 wrapped that tight, fitting it in a 1.5 collumn is gonna be tough. To help with kinking, you can try filling the tube with sand or salt before wrapping it. Good luck

[durgan]

Great, thanks Mulekicker. I will try 1/4". 3/8" seems like it might not fit if I wind it on a 3/4 inch pipe.


Cheers

[rad14701]

Common rule of thumb is that your mandrel needs to be a minimum of 3x the diameter of the tubing you will be wrapping around it... Use 1/4" on a 3/4" mandrel... If you really want to get fancy you could incorporate a 1/2" cold finger down the center for added cooling capacity...

[durgan]

Thanks for the information. I will try that cold finger in the middle. I appreciate the quick feedback.


durgan

[rad14701]

Thanks for the information. I will try that cold finger in the middle. I appreciate the quick feedback.

The trick with the cold finger is to solder the 1/4" into/onto the 1/2" before winding if possible... I've done it by soldering it first and then slipping the 1/2" inside the 3/4" for winding... No tricky bending hoopla...

[durgan]

Thanks rad. I plan on using a pipe bender and salt to assist in the process. I am not sure if I need to heat up the copper before bending to make it easier or if it matters.

[rad14701]

Thanks rad. I plan on using a pipe bender and salt to assist in the process. I am not sure if I need to heat up the copper before bending to make it easier or if it matters.

The coiled copper is pre-annealed...

[durgan]

Okay. Thanks

[myles]

If you pack with salt there is a bit of leway on the general rules.

My reflux condenser is 8mm (5/16") tube and my inner coil was wound on a 1/2" mandrel.



The normal rules apply to EMPTY tube, and they probably also assume the use of a bending tool. Bend SLOWLY and youcan get away with a lot.

[durgan]

Thanks myles. The pics really help. I just bought a bunch of copper to experiment. I have 1/4" and 3/8" with a foot of 1/2". Of course the hardware place was out of most fittings but at least I can get started. It sounds like you can just pack the tubes really tight with salt and plug both ends while working slowly. I was wondering if I could get a cold finger in the center and maybe a double coil of 1/4" to fit into a 1.5" diameter column. Guess I will find out.

I appreciate the advice.