Valving arrangement for a negative pressure ventilator

A valving arrangement primarily intended for use with an air blower means to selectively draw air through and drive air through a primary flow channel, said valving arrangement including:

• air blower means having a main body with an inlet and outlet and means for moving air through said main body from said inlet to said outlet, said air at said inlet being at a negative pressure less than ambient air pressure and said air at said outlet being at a positive pressure greater than ambient air pressure,
• a primary flow channel, and
• valve means operably positioned between said air blower means and said primary flow channel, said valve means having a valve housing with at least first and second separate inlets, at least first and second separate outlets, and at least one passageway in fluid communication with said primary flow channel,
• said valving arrangement further including a first flow path for said negative pressure air extending between said first outlet of said valving housing and the inlet of said air blower means, a second flow path for said positive pressure air extending between the outlet of said air blower means and the first inlet of said valve housing, said second outlet of said valve housing and said second inlet of said valve housing being respectively in fluid communication with ambient air, and
• said valve means further including a single, one-piece valve member and means for moving said single valve member between at least two positions, said valve member in one position placing said first flow path in fluid communication through said passageway with said primary flow channel and through said second inlet of said valve housing in fluid communication with ambient air while placing said second flow path in fluid communication through the second outlet of said valve housing with ambient air to vent substantially all of said positive pressure air from said air blower means to ambient air and said valve member in another position placing said second flow path in fluid communication through said passageway with said primary flow channel and through said second outlet of said valve housing in fluid communication with ambient air while placing said first flow path in fluid communication through said second inlet to said valve housing with ambient air to draw ambient air through said second inlet in said valve housing into said air blower means through said first flow path.