Abstract: A lightweight and portable volumetric spirometer for measuring the volume of and rate of flow of air inhaled by human lungs. The device includes a movable piston within a first transparent cylindrical chamber provided with calibrated markings along its surface for measuring the volume of air withdrawn from the chamber. The first chamber communicates with a breathing tube assembly through which the user inhales. The breathing tube assembly is uniquely adapted so that the inhaled air flow is divided into two fixed portions, one portion of which comes from the chamber, the other portion of which comes from a second chamber communicating with the outside atmosphere. As air is inhaled, the piston rises to a height that can be related to the total volume inhaled. Preferably, there is a counterweight in the second chamber which also rises during inhalation to counterbalance the resistance to movement of the piston and which gives an indication of the rate of inhalation.

Abstract: A lightweight and portable volumetric spirometer for measuring the volume of and rate of flow of air inhaled by human lungs. The device includes a movable piston within a first transparent cylindrical chamber provided with calibrated markings along its surface for measuring the volume of air withdrawn from the chamber. The first chamber communicates with a breathing tube assembly through which the user inhales. The breathing tube assembly is uniquely adapted so that the inhaled air flow is divided into two fixed portions, one portion of which comes from the chamber, the other portion of which comes from a second chamber communicating with the outside atmosphere. As air is inhaled, the piston rises to a height that can be related to the total volume inhaled. Preferably, there is a counterweight in the second chamber which also rises during inhalation to counter-balance the resistance to movement of the piston and which gives an indication of the rate of inhalation.