This paper presents and compares three volume sensors to be used in mechanical ventilators developed in laboratory: volume sensor based on the Pitot tube, volume sensor based on the Venturi tube and infrared(IR) volume sensor. The three sensors were calibrated and tested with a mechanical ventilator in Pressure-controlled Ventilation (PCV) mode. The maximum pressure changed, keeping textitPositive End-Expiratory Pressure (PEEP) and respiratory rate fixed. For each maximum pressure value: the value measured by the sensor was compared with the reference value, the value informed by the mechanical ventilator. The infrared sensor showed better performance for the specific application in a mechanical ventilator, being the only sensor considered adequate between the tested ones.