Patent ID: 7380551

Claim:
In a breathing apparatus of the type having a facemask, a source of breathable gas under pressure, a first conduit operatively leading from said source of breathable gas, a filter system comprising a filter and/or a decontamination medium, a second conduit operatively leading from said filter system, a blower adapted to move air under positive pressure through said filter system and into said second conduit, a third conduit operatively connecting said first and second conduits to said facemask, a valve assembly operatively associated with said first and second conduits, adapted to control the flow of air from said filter system and pressurized gas from said source of breathable gas, such that breathable air is supplied to a user; wherein the improvement comprises: a sensor adapted to determine whether air emerging from said filter system is safely breathable and comprises at least 19.5% oxygen; a signal generator operatively associated with said sensor, adapted to generate a signal indicative of whether said air emerging from said filter system is safely breathable and comprises at least 19.5% oxygen; and a controller associated with said valve assembly and adapted to control said blower in order to move ambient air into and through said filter system, said controller further comprising a switch in electronic communication with said sensor, said valve assembly, and said blower, said switch being configured to selectively open and close separate portions of said valve assembly in response to a predetermined reading from said sensor and to selectively start and stop said blower in order to move said ambient air such that said controller may open and/or close said valve assembly or start or stop said blower in order to allow a user to breathe cleaned air or pressurized air.