It is important to first understand that the unit moves solvent using differential pressure. Solvent evacuates from the cans which are at a higher pressure (30 – 40 PSI) into the extractor which is at a low pressure (-29″ Hg). As the can empties, the pressure in the extraction unit increases until it equalizes with the can. The first portion of solvent in the can unloads as a result of the vapor pressure of the gaseous butane pushing out most of the liquid butane. The can-tapper needs to be tapped about an inch up from the bottom of the can so that only liquid solvent comes out of it. The remaining solvent in the can needs to be removed with a temperature exchange, such as using ice water to chill both the recovery tank and the collection chamber. The coldness will cause a pressure differential, condensing the solvent back into a liquid.
Posted in: Solvents