The Marion Labs Spirostat used a disposable turbine sensor. An optical pickup counted the revolutions and converted them to volume. A volume-time curve was printed onto Polaroid film and the plastic overlay was used to measure FVC and FEV1. The turbine was small (less than 1/2″ in diameter) and resistance through the sensor was high. Manufactured and sold around 1980. Picture found at http://www.ebay.com/itm/MARION-SPIROSTAT-PHOTOMETRIC-RECORDING-SPIROMETER-/330880226526?pt=LH_DefaultDomain_0&hash=item4d09ff94de
Collins Tissot Spirometers, probably 125 and 60 liter capacities. Harvard Apparatus multi-purpose water seal spirometer. All probably from 1970’s to 1980’s.
