The system is set up very similar to nitrous. You have a tank filled with CO2 under pressure so that it is a liquid (Vapor pressure of CO2 is about 860 psi @ 70 F). The liquid CO2 is pressurized all the way to the solenoid right before the Interfreezer. When you open the solenoid the CO2 rushes into the Interfreezer and loses pressure, therefore becoming a gas. You must find somewhere to vent the gaseous CO2, whether it be through one of their more "ingenious" products or through a vent tube. They do have a terrible website, hopefully they are in the process of updating. I plan on calling them and getting the specifics of their system, I'll post my findings to try to shed some light on the mysterious Interfreezer.