ISO 2975-7:1977 PDF

Overview

ISO 2975-7:1977 specifies the transit time method using radioactive tracers for measuring water flow rate in closed conduits (pipe flow). Part VII of the ISO 2975 series, it describes the principle of labelling fluid parcels with a radioactive tracer, recording concentration/time distributions at two detector cross‑sections spaced a known distance apart, and deriving flow rate from the tracer transit time. The method applies where a tracer solution can be injected and effectively mixed with the conduit flow - adequate mixing being fundamental to valid results.

Key topics and technical requirements

• Principle: Measure the transit time of labelled fluid particles between two detector positions; flow rate Q = V / t where V is volume between detectors and t is transit time.
• Mixing requirement: Tracer must be sufficiently mixed at the first detector so recorded distributions represent mean flow. At low Reynolds numbers (Re