How it works:
The BB-1.0 CO2 Extractor works by condensing the intake supply of CO2 gas into a heavy dense cold liquid which fills the process vessel. With temperature control and back pressure regulation, material in the process vessel is pushed through media of your choosing, a tri-fold filter gasket, and two in-line filters (various micron sizes available) achieve a wide range of capabilities in isolating and filtering specific components. The filtered material accumulates in the collection vessel as the CO2 passes back into a gas leaving the heavy botanical mass at the bottom to be collected.
If a sample of liquid CO2 were sealed in a closed container, so that the volume remained constant, the liquid would boil off, until the amount of liquid and gas were constant. This is known as the liquid-vapor equilibrium. If the liquid-vapor sample were then heated, the density of both the liquid and vapor change, while the overall volume of the container remains constant. Two changes take place; first, as the liquid is heated, where it both expands and evaporates such that the resulting density of liquid is reduced.
Alternatively, the additional gas added to the vapor sample from the evaporating liquid combined with the effect of the expanding liquid compresses the gas. In other words, more gas and less space results in a greater vapor density.
As shown by comparing Figure 1 and Figure 2, when the sample reaches 30.8˚C the densities of liquid and vapor CO2 are identical, at 0.4641. When this happens, the resulting sample is a phase where the gas and liquid, due to identical densities, will also have identical buoyancies, meaning the line between liquid and gas will disappear. This temperature is known as the critical point.
The phase diagram as depicted above shows the relationship of temperature and pressure to the phase of carbon dioxide. Given a temperature and pressure, we can easily see which phase the CO2 is in. Crossing any of the lines separating regions translate into a phase transition.