Title: Spirometer

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Abstract: The spirometer comprises a housing having walls defining a turbine chamber, an antechamber having a blow-in opening and having an annular portion around it and a plurality of passages extending from the annular portion tangentially into the turbine chamber. A shaft extends through the turbine chamber and an air wing rotor is secured to the shaft and is located in the turbine chamber for rotation by the blowing air directed in through the blowing opening and the antechamber and through the passages into the turbine chamber. The housing has a portion with a dial having indications thereon and a pointer and a drag pointer rotatably mounted in the housing over the dial and is movable over the dial to indicate the blowing rate. A reduction gearing is connected between the shaft and the pointer and the drag pointer to rotate the pointer and the drag pointer upon rotation of the shaft. A manually operable, disconnectable coupling is connected between the shaft and the pointer for disengaging the pointer. A zero return spring acts on the pointer to bias it towards a zero position and a return knob is connected to the drag pointer for moving it manually back to zero separately from the pointer.


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