To desorb the HC from the Activated Carbon, a dry screw vacuum will pull vacuum inside the vessel. The level of vacuum will depend on the HC molecule adsorbed and the emission level.
The pumps are frequency controlled to adapt the energy consumption to the mass of HC at the inlet of the VRU.
The desorption end vacuum pressure « set » depends on:
Desorption end vacuum pressure reached by the system is stable over time and avoid overload of the AC (higher life time, lower risk of hot spot)