Pressure destillation and refillable spray cans

Sometimes I miss the availability of products in spray cans, so I made effort to fill them in spraycans on my own. Therefore at first I gained some experience with liquid compressed gases as propellants by building a small destillation apparatus for liquid butane/propane. The apparatus consists of two tin plate spray cans, connected by a copper capillary tube. Each can is equipped with schrader valve which I soldered into the wall at the top of the can. The upper can is filled with hair spray by the schrader valve and heated by a hot (60°C) water bath. The lower can is cooled with iced water. By this temperature gradient, the propane/butane mixture in the hairspray filled can begins to boild and slowly condenses in the cooled can. After 1-2 hours I collected 200mL propane/(iso-)butane propellant mixture from 400 mL hairspray. This amount of liquid gas mixture is much cheaper than the same amount of commercially available (odorless) butane lighter fuel - and has a significant lower boiling point, resulting in more available pressure (~2 bar). The collected liquid gas can conveniently be extracted by the normal valve of the lower spray can into a storage vessel. As storage vessel I use a spray can, additionally equipped with a schrader valve. The residue of the hairspray, an ethanolic solution of ... what ever... is removed the same way from the upper can. 

To make your own XY-spray, you need another empty spray can with an additionally schrader valve and hold it upside down. Fill the can by the shrader valve with the desired liquid/solution (preferrably ethanol or petroleum based) and vent it by the normal exit valve of the can from time to time. I recommend a syringe for charging the content into the can. For a 400 mL spray can you should not exceed a product charge of 200-250 mL, because you have to add a propellant volume of at least 100-200 mL. This can be done by adding a weighened amount of the liquid gas (density ~0,5 g/mL). In practice you have to weigh your propellant storage vessel or the filled spray can repeatedly. Also you must not fill the can up to the brim, but let some room for thermal expansion. Otherwise elevanted temperatures maybe led the can to burst ;)

DIY Pressure destillation apparatus

Cleaning of the apparatus by extracting the hot hairspray residue (basically denaturated, water free ethanol with some hair-styling chemicals) via the outlet valve of the can

Extraction of the collected propane/(iso)-butane from the lower can into a storage vessel