BAD, incredible fire risk and in general will put a room way over its limit of unprotected flammables.

 

 

Flammable liquids storage cabinet is built in.  Much better.  Note that fire code says not more than three such cabinets in a single fire control area.

 

More:

"Solvent purification systems"

In the late 1990s and early 2000s, "solvent purification systems" based on forcing solvent through activated alumina and other solid media became increasingly widespread.  The original design came out of a research lab in a CA university (please send this info if you have it or a link to it, I can't find this quickly anymore, swihart@purdue.edu), and the original homemade systems looked something like this one at the left.  I believe they did use the same cylinders that were used for LP gas.

These were highly acclaimed as much much safer than the old fashioned solvent purification systems used since before any of us were born.

 

The first sold-by-vendor units looked something like this at right.

Units such as the homemade one above and the early vendor-supplied one at right had an extreme major flaw, which was overlooked completely and repeatedly by the people making them and the people buying them, which is that in general, if you fill up three or more these very explodable canisters with flammable liquid such as THF, ether, DMF, hexane.... you have created a situation which is very far out of compliance with the requirements of fire safety laws of your state and federal governments, as well as clauses in your property insurance agreements.

You just can't load a room up with this much flammable liquid.  There is never a problem if there is never a fire, but the limitations exist because fires happen, and they are made devastating, deadly, and incredibly expensive by the presence of large quantities of flammable liquids.

 

Now, most of the units available commercially look have flammable liquid protection built in, as pictured at left.  The insulated cabinet performs a ridiculously simple but critical function, which is keeping the temperature inside from skyrocketing as fast as the temperature outside the cabinet, during the first 5 - 10 minutes of a fire near by.  That's all.  That first 5 - 10 minutes is where the difference is made between a fire killing people or not, costing 3 million dollars or 3 thousand dollars, and taking the whole floor or the whole building versus only destroying quite a bit of one or two rooms.  (Presuming that there are also some other standard fire protection controls in place, and that fire suppression such as halon or sprinklers or firefighters will present itself in a short time to eliminate the fire.)

If you own a solvent purification system that has no flammable liquid protection, do not use more than 5 gallons total flammable liquids in it at one time.  And replace it as soon as possible with a system that includes a fire protection cabinet.  See http://www.purdue.edu/rem/safety/flam.htm for information on flammable liquid limits.