A mains electricity (AC-powered) device designed to measure several or all respiratory-gas volume and flow parameters needed to evaluate basic pulmonary function [e.g., vital capacity (VC), peak expiratory flow (PEF), forced expiratory volume (FEV), and forced expiratory flow (FEF)]. It is an instrument used in a clinical setting with a mouthpiece and tube attached to a computerized unit to process the data from patient ventilatory efforts, volume and/or flow sensors, a display, and usually a graph recorder. The data are compared to standardized values or the patient's former values to help identify or evaluate chronic pulmonary disorders such as asthma, emphysema, or bronchitis.