Ultrasonic flow meters are non-intrusive, important devices that make effective use of acoustic vibrations to successfully measure the flow rate of any specific liquid. Typically, there are two types of ultrasonic flowmeters: doppler and transit time. While both of them essentially operate on a similar principle, the technology that makes both of them work varies to a great degree. When deciding which flowmeter is suitable for you, it is important to understand the usefulness of both types.