Hi All…I’m totally new to this forum, and am already a big fan! I have been doing thin-film distillation for quite some time. My gear has included:
Home-brew (well, glassblower built!) falling film still, based on the design in old Kontes catalogs, but upsized about 3x. Welch duo-seal, air-cooled diffusion pump, mercury-filled tilting McLeod gauge for vac sensing (and got ~25 mTorr). ca 1979.
ca 2016: 2" Pope and ~4" Leybold-Hereaus WF units. Both of these are at least 35 years old. 1" bore vacuum manifolding with Varian M-2 diffusion pump, Alcatel and Savant roughing pumps, vac sensing with Kurt Lesker convection gauges, data logging via LabVIEW. Pretty flexible setup that allowed either still to be high pressure (terp stripping) or low (3-8 mTorr for cannabinoids).
…after which I graduated to these two 4" Popes, mostly doing terpene stripping in front of a ChemTech KDL-6.
…which brings me to my comment regarding vacuum. Earlier in this thread mention was made of turbo pumps vs diffusion pumps. I’ve worked with turbos a fair bit, but only in ‘dry’ systems (mass spectrometers, gas sampling systems), and I really don’t think they work for distillation systems. Mainly because their controllers almost always shut down the turbo if there’s a pressure pulse, which can be relatively small. Then, the controller will not allow a restart until the vanes have come down to a slow speed, then they can rev back up. That would considerably bollocks a distillation! Moreover, servicing or rebuilding these things is a shop visit. I’ve seen turbo pumps in the salvage yard of my previous employer that had failed…the vanes had turned into something that looked like steel wool pitched into a blender! Besides…the things are expensive…