21 C.F.R. § 868.1840Download PDFCurrent through September 30, 2024Section 868.1840 - Diagnostic spirometer(a)Identification. A diagnostic spirometer is a device used in pulmonary function testing to measure the volume of gas moving in or out of a patient's lungs.(b)Classification. Class II (performance standards). 21 C.F.R. § 868.1840