The initial mention from here.



Brainstorming for this idea finally turned out a very possibly viable solution. SWIM's first idea was to simply attach a plastic jar to the end of a THP in a way that would allow it to be easily removable, but he didn't like the idea of pressurizing such a ghetto-rigged contraption. But one night, he lay awake trying to think of a more elegant solution, and the setup pictured below occurred to him.

Essentially the THP just sits in a hole cut into the lid of the plastic jar with some sort of a seal between them. The jar would then fit over the THP, enclosing it, and screwed into place. The valve could be done in the same manner as CosmicLion's contraption, but SWIM would likely use a presta valve with a bike pump, instead. This has been heavily inspired by CosmicLion, but this one attempts to solve two issues found in his device: It's compatible with any sort of extraction related filtering, no matter what the solvent, due to the use of an internal HDPE container, and it reduces the chances of an explosion compromising the contents--the pressurized container not acting as the vessel.

While this idea is primarily intended to aid in separating extraction solvent from source material, it could likely be converted for filtering out precipitates or other particles, particularly by use of a screen inserted into the THP--something that may prove handy, regardless.

This should be an easy build, we'll see what comes of it.

Great idea!

What if we use negative pressure instead of positive?

I suggest to insert THP into a filtering flask and connect it (the flask) to a water aspirator. They are very cheap. We would not need an air pump and an outer container for THP. We will also eliminate a chance of explosion due to possible excessive pressure.

I have a few half-baked ideas how to assemble a filtering flask from some household items. I did not develope and test them because I bought a real one.

Well, given a vacuum flask, and one of these bad boys:

I'm sure it's possible to adapt it for use with all sorts of filter funnels, but all SWIM needs to make this one happen is the proper sized plastic jar and a solution for the seal on the lid. He'd like to develop this idea prior to making any serious investments.

That is so cool! I'm definitely going to try this.

Edit: I did try something similar once before...and it sploded.
But, that was using electrical tape.
This time will be different.
yeees

Just a quick update, so far SWIM's gotten it to work somewhat, but has had difficulty with keeping a sealed environment using what's available to him around the house. Some sort of seam-sealing tape and shellac (or silicon spray?) may work between THP and lid, but plumber's tape would probably be helpful for the threading on the lid. Also, finding the adequate container has been troublesome.

So this may not work as well as hoped, but the alternative of using negative pressure is still under consideration:

http://www.avogadro-lab-supply.com/item.php?item_id=425

This could be used in conjunction with a normal aspirator.

http://wardsci.com/product.asp?...502&mr:referralID=NA

or something like this could be used.

and for reference of how this would all be put into practice:

http://chestofbooks.com/crafts/...o-Make-an-Aspirator.html

Isn't the original idea just a more dangerous method that achieves more or less the same thing as vacuum filtration? I mean, why applying positive pressure which could produce an explosion, when you could just suck? Furthermore, vacuum filtration apparatus and techniques are very well developed, so I don't see a need to reinvent this.

I wouldn't say it's necessarily dangerous.... I don't think we're talking flying shrapnel here. SWIM's never encountered a filter clog in THP he could ever imagine causing the proposed device to explode anyway. The whole point is to use materials that are readily available to accomplish something useful, but SWIM may just pursue the negative pressure avenue anyway. The collection vessel to which the aspirator is to be connected will require some DIY to make it work for THP.

Great idea amor, ive considered before just constructing some kind of expresso machine for these kinds of uses, and im glad to see someone already at work!

It's been a while, but it proved far too difficult for SWIM to find adequate supplies for this. He had two developments however:

-Firstly, using a bit of loosely packed cheesecloth, rather than tightly packed cotton-balls or cotton rags works very well for hastening drainage, alongside simple avoidance of dumping of extraction mixtures (as with limtek) directly into THP until the very last flush, allowing it to completely drain only then.

-Also, the usage of an HDPE spray bottle with the nozzle in place but the straw removed makes a decent pressure powered separatory funnel when used upside down with the bottom cut off. SWIM will be attempting to make this work as a simple man-powered vacuum filtration device with a couple methods he has in mind--perhaps even a combination of the two. A simple screen shaped into a dome could be placed in the cap with some cheesecloth locked in it, blocking passage into the nozzle. Also, a screen could be heated, then placed in the neck of the bottle to allow filter paper to be used. Even if the spray nozzle doesn't turn out to have enough pressure for most filtration purposes, it could always be adapted for use with another negative pressure generating device.