A tubular body is operatively coupled to an oral nasal mask and provided with lateral apertures adapted for fluid flow. A flexible valve is mounted onto one end of the tubular body and adapted to seal the lateral apertures under normal operation conditions and expose the lateral apertures for fluid flow during emergency operation conditions. The sealed lateral apertures keep exhaust gases from escaping the oral nasal mask and contaminating the interior of the diving equipment during normal operation conditions. The exposed lateral apertures allow air from an alternate source to reach the mouth and nose of a user covered by the oral nasal mask during emergency operation conditions. The exposed lateral apertures allow excess water to be removed from inside the diving equipment. The valve system may be implemented as an integrated regulator mount nut/valve system.