It is well- known that liquid will stand freely within a vertical column with the bottom of the column being open in a reservoir of the liquid and the top of the column being exposed to the vacuum. The free standing of the vertical column has to do with the air pressure being applied to the surface of the liquid reservoir. The density of the liquid determines the height of the standing liquid.

Perhaps the most familiar example of this physical principal is the rudimentary barometer often used to demonstrate the pressure of the earth's atmosphere on a column of mercury about 30 inches high. If the atmospheric pressure changes, so does the height of the column of mercury. This is the principal on which the modern barometer and barometric pressure is based.

A column of salt water will stand approximately 33 feet in a vertical tube. It is at this height that the molecular weights of a molecule of H20 relative to the pull of gravity are in equilibrium. Therefore, it is at this height that evaporation will generate pure water vapor and leave behind heavier residual impurities, under natural atmospheric conditions.

However, it is also well-known that water will vaporize at lower temperature when atmospheric pressure is reduced, such as in an evaporation chamber. When vacuum conditions are created at sea level, water vapor can be produced at lower temperatures. The energy implications of this should be obvious. The "Passarell" process takes advantage of these principles in the distillation phase, but the process does not end here. The pure water vapor generated by distillation is drawn into a compression process where it is compressed and condensed using an advanced design compressor. The compression process improves the efficiency of the distillation by creating the vacuum that reduces the pressure in the evaporation chamber enabling the input sea water to vaporize at a lower temperature. The compressor centrifuges the pure water vapor after it is drawn through a demister (removing residual impurities) causing it to compress against the tubes in the collection chamber. The compression of the vapor causes its temperature to increase. The heat generated is transferred to the input water falling in the tubes causing the water in the tubes to vaporize. The water vapor condenses on the outside of the tubes as product water.