Differential pressure control of contiguous spaces

Claim 1

IN COMBINATION AN ARRANGEMENT FOR MAINTAINING A SUBSTANTIALLY CONSTANT AIR PRESSURE DIFFERENTIAL BETWEEN MEANS FORMING APERSONNEL SPACE SUBJECT TO BEING PLACED IN COMMUNICATION WITH THE OUTDOORS FROM TIME-TO-TIME, AND MEANS FORMING A CONTIGUOUS EQUIPMENT SPACE SEPARATED FROM THE PERSONNEL SPACE BY A WALL THROUGH WHICH AIR MAY EXFILTRATE FROM ONE OF SASID SPACES TO THE OTHER: (A) MEANS FORMING AN AIR RECIRCULATING AND CONDITIONING SYSTEM INCLUDING A PRESSURE SIDE AND HAVINB BOTH A RECIRCULATIONG AIR AINLET AND CONDITIONED AIR OUTLET IN COMMUNICATION WITH SAID PERSONEL SPACE, AND BLOWER MEANS THEREBETWEEN; (B) MEANS FORMING A SEPARATE AIR RECIRCULATING AND CONDITIONIN SYSTEM INCLUDING A SUCTION SIDE AND HAVING BOTH A RECIRCULATION AIR INLET AND A CONDITIONED AIR OUTLET IN COMMUNICATION WITH SAID EQUIPMENT SPACE, AND SECOND BLOWWER MEANS THEREBETWEEN; (C) MEANS FOR ADMITTING OUTDOOR AIR TO THE SUCTION SIDE OF SAID PERSONNEL SPACE SYSTEM; (D) AIR PASSAGE MEANS CONNECTING SAID PRESSURE SIDE OF SAID PERSONNEL SPACE SYSTEM WITH SAID SUCTION SIDE OF SAID EQUIPMENT SPACE SYSTEM; (E) AND MEANS FOR CHANGING THE AIR FLOW RESISTANCE OF AT LEAST ONE OF SAID SYSTEMS TO VARY THE AIR FLOW EXCHANGE THROUGH SAID AIR PASSAGE MEANS.