The ranked assignee list covers 63 companies across 274 records in scope, with one assignee holding 71 records — well ahead of the fifth-ranked holder’s 12. That leader’s position, combined with the top five collectively holding 46.0% of all records, points to a small group of established flow-metrology and process-instrumentation manufacturers rather than a wide field of equal competitors. Anyone assessing competitive risk in this space should start with that concentrated group before looking at the long tail.

Filings peaked at 23 in 2018 and fell steadily to 9 by 2021 and just 1 by 2024, an -89% drop across that three-year span. This pattern is consistent with a technology whose core transit-time and clamp-on principles have become well established, pushing new filing activity toward incremental refinements like self-diagnostics rather than fundamental redesigns. It is worth noting that 2025-2026 figures are still incomplete because publication typically lags actual filing by around 18 months, so the most recent apparent slowdown should not be read as the final word.

Core flow-measuring classification G01F appears on 76.6% of the 274 records, indicating dense claim coverage there. By contrast, classes tied to antenna and transducer-array design (H01Q, 3.3% of records) and radar/positioning-based sensing (G01S, 11.3%) show meaningfully less density, suggesting these adjacent signal-processing and array-geometry approaches carry comparatively more room for new claims. A prior-art search focused specifically on those subclasses is a reasonable next step before assuming the whole field is saturated.