Ventilation system for an isolation enclosure

A ventilation system for an isolated, depressurized enclosure having an air admission and an air exhaust device, said air admission device comprising:

• a valve body having an orifice therein and communicating on the one hand with an air admission pipe with the interior of said enclosure, so that air flowing from said air admission pipe flows into said enclosure through said orifice,
• a regulating valve connected to the valve body for closing said orifice,
• control means on said valve body for controlling said regulating valve, said control means being responsive to changes in the pressure in the interior of said enclosure, said regulating valve being opened by said control means when the pressure inside said enclosure is below a predetermined level,
• an air exhaust pipe mounted on said valve body for exhausting air from inside said enclosure when vacuum inside said enclosure decreases, said air exhaust pipe being in fluid communication with said valve body
• a low-vacuum safety valve mounted on said valve body for closing said air exhaust pipe,
• said control means for controlling the regulating valve further comprising displacing means on said value body for displacing said low-vacuum safety valve, said control means and said displacing means progressively opening said low-vacuum safety valve as said regulating valve closes and progressively closing said low-vacuum safety valve as said regulating valve opens.