The present application includes an independent and redundant measurement of anesthetic concentration, based on acoustic time-of-flight measurements, added to an anesthetic vaporizer. The redundant anesthetic concentration measurement is used to make the vaporizer inherently safe by design and monitor true vaporizer empty. Further, using an acoustic wave splitting technique and the time-of-flight measurements, the flows at the vaporizer inlet and outlet are computed. The flow measurements are used to monitor carrier gas loss, anesthetic consumption, and anesthetic delivery time remaining and provide such information to the vaporizer operator.
