Certified Pulmonary Function Technologist (CPFT) Practice Exam

Which device should NOT be used to measure high flow rates?

1. Turbine

2. Peak flow meter

3. Ultrasonic flow meter

4. Cylindrical gauge

The correct answer is: Turbine

The rationale for selecting the turbine as the device that should not be used to measure high flow rates lies in its inherent operational limitations. Turbine flow meters function by utilizing a rotating blade mechanism that is optimal for moderate flow rates. When subjected to high flow rates, the turbine can be subject to mechanical strain, leading to inaccuracies in measurement or potential damage to the device. In contrast, other devices like peak flow meters, ultrasonic flow meters, and cylindrical gauges are typically designed to adequately handle higher flow rates. Peak flow meters, for instance, are specifically tailored for assessing the peak expiratory flow rate, often used in managing conditions like asthma, which can involve high flow output. Ultrasonic flow meters utilize sound waves to capture measurements across a wide range, including high flow rates, while cylindrical gauges can also measure a variety of flow rates effectively, particularly in specialized applications. Therefore, the turbine's design and functionality make it less suitable for accurately measuring high flow rates compared to the other listed options.