Ultrasonic Flowmeters

Ultrasonic Flowmeters

Ultrasonic flowmeters measure volumetric flow in liquids and gases using acoustic signals rather than intrusive mechanical elements. This enables reliable flow measurement across a wide variety of media independent of electrical conductivity and, for many applications, largely independent of pressure, temperature, or viscosity. Inline ultrasonic meters are commonly used where traceable, guaranteed accuracy is required, while clamp-on designs mount externally for retrofit or temporary measurement without interrupting the process.

A common method is differential transit time: ultrasonic pulses are sent alternately upstream and downstream between two transducers. Flow accelerates the signal in the direction of flow and delays it in the opposite direction; the measured transit-time difference is proportional to the flow rate.

Key benefits include a full-bore measurement path with no moving parts and essentially no additional pressure loss. Minimal wear and the lack of internal obstructions support long service life, while reduced maintenance requirements improve availability in high-uptime systems. Inline and clamp-on architectures enable both permanent metering and diagnostic/verification campaigns using the same measuring principle.

Typical applications include large-diameter water transmission, cooling water and utility loops, chemical services where aggressive fluids or high pressure make intrusive sensors undesirable, and balancing tasks during commissioning or debottlenecking. Clamp-on technology is particularly effective for non-invasive measurements on existing piping, including plastic, steel, and lined or unlined composite constructions, and for very large diameters (up to DN 4000 in the referenced portfolio).

Specification focuses on the acoustic conditions required for stable measurement: full pipe, appropriate signal coupling, and awareness of bubbles, excessive solids, or strong stratification that can disturb the sound path. For clamp-on meters, pipe wall thickness, liner presence, and surface condition influence installation quality; for inline meters, short but defined inlet conditions and spoolpiece geometry influence uncertainty. Where custody-transfer or high-integrity reporting is required, pairing the meter with traceable calibration documentation and in-service diagnostics supports governance without adding pressure drop.

George E. Booth Co., an exclusive authorized representative of sales and service for Endress+Hauser.