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Evaporation "oven"

Discussion in 'DIY' started by SquidgyB, Apr 27, 2014.

  1. SquidgyB

    SquidgyB Member

    Messages:
    24
    Location:
    Berkshire
    So, I've been experimenting with concentrates recently, and with the local weather, availability of solvents, and my own personal circumstances what they are I've had to go down the QWISO route rather than being able to run BHO outside or do a QWET extraction.

    I've been running QWISO in a well ventilated kitchen with an electric oven, extractor fan and simply leaving an open jam jar (US equivalent; mason jar?) for a few hours at low temp (50-70°C, 120-160°F). While I get pretty decent results (the most recent from good quality material and keeping the extraction temp below -16°C/3.2°F) I don't like the safety aspect of evaporating alcohol in this way.

    Also of note is that the final part of the process for me will be adding EJMix (or my own PG/PEG400 mix, if I ever run out of the good stuff - seems to work just as well). So the final phase of the concentrate is liquid - this is important for the evaporation method I have planned here, as I won't get a thin film on glass to be able to do a really effective final purge. Also, I don't (yet) have a working vacuum setup - although I have a fridge/freezer pump lined up and I have a vacuum gauge/switch and relay ready to go, so that's another option. The benefits of the method I will describe over a vacuum purge is mainly that I will be able to use a very small final container without the risk of the concentrate boiling under reduced pressure causing a mess.

    Right - the main elements of the build are these:

    Heat Pad - I made this from a few small aluminium heatsinks and a soldering iron heater. The controllers I have for the heaters are very small, have an LCD display and can go as low as 50°C and hold the temperature of the ceramic heater accurately to ~1°C. The ceramic heater is set into a groove in the heatsink fins with 1200°C fire cement. The heatsink block is then glued into a small steel tin with JB weld. There's plenty of different ways to do this, I just made this from what I had at hand. Any controlled heater would do - enough nichrome wire or a ceramic heatsink and a control circuit could be set up for the same effect.

    Air replacement (and inadvertently, agitation) - I came up with this idea after thinking about some kind of "duct" flowing over the jar, replacing air and expelling solvent along the duct and out of a window. I was stuck on the idea of using a computer fan and some wadding as a filter, but I didn't like the size of the overall design, the potential for electric motors and fumes to mix, effective filtering of that volume of air etc. Anyhow, my idea is to use a cheap aquarium diaphragm air pump, both as a base for the oven, and as a provider of clean air (felt filtered) - with very little potential for ignition of the alcohol. As well as providing fresh air, the pumps vibrate a fair bit. Sitting the jar and heat pad on top of the pump should give just enough movement to agitiate the liquid in the jar enough to refresh the air/liquid erm, whatchacallit, so the alcolol should purge fully over a few hours at low heat. The jar used will be closed - with two tubes coming in through the lid; in, and out. The "Out" tube will be fairly long, and lead out of a window - expelling alcohol vapour which forms in the jar.

    My main concerns at the moment are whether the tubing I'll use will be safe to use with alcohol - that said the vapours are constantly being removed, so even if it does effect the tube, as long as no alcohol condensation makes it back into the concentrate after touching the tube, I'll be happy.

    I don't have any pictures yet, mainly because I'm halfway through building it.

    Anyone have any more ideas, while it's still in the formative stages?
  2. Bouldorado

    Bouldorado Well-Known Member

    Messages:
    933
    Location:
    CO
    I think your setup is very safe for the small quantities of ISO you're evaporating. Here's an MSDS for ISO: http://www.sciencelab.com/msds.php?msdsId=9924412

    Basically, if you don't have an ignition source (open flame, sparks) chances of an explosion are very low, especially in a well ventilated area.
  3. SquidgyB

    SquidgyB Member

    Messages:
    24
    Location:
    Berkshire
    A small update; it works! I'll post a pic of the unit when I get back from my holidays. It's certainly a bit shonky looking but it evaporates well enough and does everything I want to :D
    Puffers likes this.

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