turepressure inside the pot .the control system could rectify the pressure in the pot (by switch on/foff the inlet.outlet valve) to balance with the pressur inside of the package .pressure balance system is critical to gas pack sterilization,esp. in the process of temperature risedrop. this makes sterilization possible on air/gas pack with any percentage of air/gasorvacuum pack without damageordeformation to the packageordeformation to the packageorthe contained.this different from the others.