Spirometer

Claim 1

APPARATUS FOR THE MEASUREMENT OF PULMONARY TIDAL VENTILATION COMPRISING A VERTICALLY DISPOSED TANK MEMBER HAVING A BOTTOM WALL AND BEING OPEN AT THE TOP, INTAKE AND EXHAUST TUBES EXTENDING UPWARDLY FROM THE LOWER PORTION OF SAID TANK AND TERMINATING AT THE UPPER PORTION THEREOF, A DIVIDING BELL MEMBER MOUNTED FOR VERTICAL MOVEMENT IN SAID TANK MEMBER AND ENCLOSING THE AREA ABOVE THE UPPER ENDS OF SAID TUBES, A VOLUME OF WATER IN SAID TANK MEMBER FORMING A WATER SEAL AT THE LOWER OPEN END OF SAID DIVING BELL, A CONDUIT CONNECTED TO SAID INTAKE TUBE, A FIRST AND A SECOND NORMALLY CLOSED CHECK VALVE IN SAID CONDUIT, SAID CONDUIT HAVING MEANS ARRANGED INTERMEDIATE SAID CHECK VALVES FOR CONNECTION TO THE RESPIRATORY SYSTEM OF THE PATIENT, SAID FIRST CHECK VALVE BEING NORMALLY CLOSED AND MOVABLE TO OPEN POSITION UPON EXHALATION BY THE PATIENT FOR THE ADMISSION OF EXHALED AIR TO THE UPPER PORTION OF SAID DIVING BELL, SAID SECOND CHECK VALVE BEING NORMALLY CLOSED AND BEING MOVABLE TO OPEN POSITION UPON INHALATION BY THE PATIENT, AND EXHAUST TUBE FOR POSITIONED AT THE LOWER END OF SAID EXHAUST VALVE MOVEMENT INTO AND OUT OF ENGAGEMENT THEREWITH, A TUBE CONNECTED TO SAID CONDUIT INTERMEDIATE SAID CHECK VALVES AND EXTENDING TO THE UNDERSIDE OF SAID VALVE FOR CONDUCTING EXPIRED AIR THERETO TO EFFECT POSITIVE PRESSURE TO SAID VALVE TO MOVE THE SAME AGAINST THE LOWER END OF SAID EXHAUST TUBE, AND SERVING TO ESTABLISH A NEGATIVE PRESSURE ON UNDERSIDE OF SAID VALVE UPOON INHALATION BY THE PATIENT TO EFFECT MOVEMENT OF SAID DIAPHRAGM DOWNWARDLY FROM SAID EXHAUST TUBE TO PERMIT AIR TO EXHAUST FROM WITHIN SAID DRIVING BELL.