[This is my first post, so I hope the pictures are posted properly]
I am planning for a 3" diameter pipe still head, so I know I can easily get two winds of the condenser coil inside it. I wound the inner coil around a 1" diameter pipe, and the outer coil around a 1 7/8" pipe. This allows for plenty of spacing between the coils as well as enough spacing between the outer coil and the still head, about 1/4". I made each coil separately, then soldered them together with a coupling when both coils were done. On the next still I make, I will do this process with one continuous piece of copper tubing.
- Finished Double Coil Reflux Condenser
How I did the salt packing. I found I could wind unpacked 1/4" tubing around a 4" diameter PVC pipe without crushing the copper tubing, so I started there. After the initial tight wind (no spacing between wraps), I stretched the coil out like a spring over the length of a 5’ long 4" diameter PVC pipe so it had a nice gradual slope to it when I turned the pipe on end. I plugged the bottom end with a small bolt and taped that end of the copper tubing in place to the PVC pipe.
I found filling the tube with salt to be quite slow, using a small 1/2 tsp spoon, so I made a machine using an old photographic film mixer and a paint roller that did most of the initial filling for me. My machine rotated the horizontal PVC pipe at a very slow rate. I bent the leading end of the tubing so that each rotation of the pipe scooped up a bit of salt from a pan of salt I place below it, and after running the machine for about 10 minutes the tube was full of unpacked salt and would not take any more.
- Fill coil with Salt - Machine
I knew that the salt would need to be packed more tightly, so my next step was to turn the pipe on end and vibrate the salt down further, then added more salt (repeated many time.) This took about an hour.
Salt packing process. With the taped end down, I ran my hands up then down the length of the pipe with the tubing wrapped around it. (No rude comments please about what this looked like. Let's just say I'm naming my reflux coil Moby Dick.
. With the bottom of the tubing taped to the pipe, and the rest of the "spring" loose, the entire tube vibrated salt down as I ran my hands up/down the pipe, making room to top it off with more salt. I kept this up until vibrating the tube did not free up more space. I capped the open end of the tube with another small bolt to keep the salt in for the tight winding that came next.
- Vibrating / Packing coil with Salt
Final Winding to 1” and 1 7/8” for condenser coils. Once packed with salt, I could easily hand wrap the 1/4" tubing around a 1" pipe with no deformation to the tubing. I did this wrap tight, with no space between wraps. To do the wrapping, I put the 4" coil of copper tubing on a 1" pipe, then secured the two ends of the 1” pipe so the pipe rotated freely. (Think of a toilet paper roll holder.) I put on some heavy gloves, held one end of the tubing securely against the pipe, and rotated the secure end while holding the loose coil end of the tubing tight against the pipe. I left about 8” unwrapped that would become the input/outlet section of the coil. This wrapping only took 5 minutes.
To space the coil with approximately 1/8” between wraps, I laid the tight coil on it's side, and pressed a Popsicle stick between the first 4 or 5 winds. I turned the coil over and did the same on the opposite side of those first few winds. I repeated this process until the entire coil was spaced. The spacing was not quite as much as I wanted with one stick, so I added a second stick to each wind. I was very happy with the results.
- Spacing the condenser coil
Attaching Coil to Cap. I measured the spacing of the input and output lines and drilled the cap so the coil would be centered. Next I drilled two large vent holes in the cap to ensure I don't blow up my still.
Comments or suggestions for improving this process are welcome. I plan to make a second still, once this one is done and I get some serious experience distilling.
Enjoy,
OtisT