Ultrasonic technologies are used for flow measurement in the form of collection of information and data pertaining to the traversed medium. Acoustic waves within the ultrasonic frequency ranges from 20 kHz to 8MHz are used to measure volumetric flow rates in pipelines. Ultrasonic systems major benefits include non-invasiveness ease of operation and installation, quick response to change in flow, increased time between calibrations, and the modular design. The noninvasive charecter of measuring ultrasonic flow leads in the applications of gas and oil pipelines measuring systems, feed water flow measurement and many other areas, where other types of flowmeters are not appropriate due to their intrusiveness or associated pressure loss. The two types of ultrasonic flowmeter are possible alternatives for flow measurement in pipe line, the transit time ultrasonic flowmeter and doppler ultrasonic flowmeter. Out of this transit time technique is used most popularly because they can easily deal with nanosecond range time intervals, high accuracy and nonexistence of moving parts –. Transit-time flowmeters are used in a variety of applications, including the measurement of raw and treated water and in different stages of the treatment process such as the measurement of settled water, supernatant, backwash, and chemical additives. The meters have also become widely accepted in large-diameter intercity custody transfer applications. Because transit-time flowmeters do not create any flow restrictions in the pipeline, they are used in many cases in which flow restrictions are undesirable. Transit-time flowmeters offer the advantage of availability for a wide range of pipe sizes, from 3/8 in. to 30 ft (10 mm to 9 m) in diameter. Transit-time flowmeters become especially cost-effective in large diameter pipelines. In addition, transit-time flowmeters are easy to install in retrofit applications with minimal or no disruptions to the flow. The components are also easy to remove during maintenance.