TS 3418

TS 3418 is a terminology and symbols standard for the measurement of fluid flow in closed conduits. It brings together the names, symbols, and explanations used in flow measurement so that pressure-difference devices, critical-flow measurement, velocity-area methods, tracer methods, electromagnetic flowmeters, and gravimetric or volumetric methods can be discussed in a consistent technical language.

Why a shared vocabulary matters in flow measurement

Closed-conduit flow measurement covers several physical principles for determining the amount or rate of fluid moving through a pipe. Differential-pressure methods rely on the pressure drop created across a constriction or primary element, electromagnetic flowmeters use induction in conductive fluids, while velocity-area and tracer methods infer flow from the distribution or movement of the fluid. This standard supports consistent use of the terms and symbols associated with those approaches.

Concept groups covered by the standard

• General terms and supplementary flow-measurement concepts
• Main terms and symbols for differential-pressure measuring devices
• Critical-flow, velocity-area, tracer, and electromagnetic measurement approaches
• Basic terminology for gravimetric and volumetric methods

As a vocabulary and symbols document, its main value is conceptual alignment rather than prescribing a single test method or instrument design. Published as equivalent to ISO 4006:1977, it serves as a reference for technical communication in flow measurement, metrology, and closed-conduit applications.