The present invention relates to a CPAP device comprising:a humidifier； anda flow generator including:a flow generator outlet,a motor having a motor outlet,a muffler chamber having an inlet coupled to the motor outlet and a muffler chamber outlet in communication with the flow generator outlet,wherein said muffler chamber includes an upper part conduit portion and a lower storage portion integrally formed with the upper part conduit portion, and wherein the lower storage portion is configured and dimensioned to store spill-back from the humidifier to prevent water from reaching electronics or the motor.
