This standard describes transit-time ultrasonic flowmeters for water supply service application in pipes running full. An ultrasonic flowmeter is a meter that uses acoustic energy signals to measure liquid velocity. There are currently two distinct types of ultrasonic flowmeters available: Doppler-effect and transit-time. The Doppler-effect meter is used exclusively for liquids containing solid particles or gases, and the transit-time flowmeter is used in a wide variety of applications in the water industry.

Transit-time flowmeters are used in a wide variety of applications, including in raw water, in treated water, and in different stages of the treatment process, such as settled water, supernatant, backwash, and chemical lines. These meters are also used in large-diameter transmission pipelines.