scope:

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.

Purpose

The purpose of this standard is to provide purchasers, manufacturers, and suppliers with the minimum requirements for transit-time flowmeters, including components, performance, calibration, and verification.

Application

Transit-time flowmeters are used in a wide variety of applications, including raw water, 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.

Transit-time flowmeters do not create any flow restrictions in the pipeline and are, therefore, used in many cases where flow restrictions are undesirable. Transit-time flowmeters are desirable for their suitability on a wide range of pipe sizes, from ³/₈ in. to 30 ft in diameter. Transit-time flowmeters become especially cost-effective in large-diameter pipelines.

Transit-time flowmeters are easy to install in retrofit applications with minimum or no disruptions to the flow. The components are also easy to remove during maintenance. An additional advantage of transit-time flowmeters is their suitability to bidirectional flow conditions.

Like any other flow measurement device, transit-time flowmeters need to be selected prudently for the conditions under which the equipment is expected to operate.