A flow box measures flow with what instrument?

A flow box primarily utilizes a pneumotachometer to measure airflow. This device operates by determining the flow rate of gas (typically air) moving through it, based on the pressure difference created as air passes through a known resistance. This ability to calculate flow is crucial for assessing respiratory function, particularly in pulmonary function tests where airflow dynamics are evaluated.

The pneumotachometer is specifically designed to provide precise measurements of both inhalation and exhalation flow rates, making it ideal for detailed respiratory analysis. Other instruments listed, while related to respiratory measurements, serve different functions. A spirometer typically measures the volume of air inhaled and exhaled but does not measure flow directly. A peak flow meter measures the peak expiratory flow rate, which is a specific metric rather than continuous flow. A capnometer is designed to measure the concentration of carbon dioxide in exhaled air, useful for monitoring ventilation rather than flow rates.