The dataset ranks 31 companies, and filing is highly concentrated: the top 5 assignees together hold 75.9% of all 108 records in scope, with the single leading assignee alone accounting for 41 filings. The gap to the fifth-ranked assignee, which holds 4 records, is large, meaning one company's portfolio effectively defines the baseline prior art most new filers must design around. Beyond the top 10, which combine for 88.9% of records, the remaining assignees each hold small, often single-digit counts, forming a long tail typical of a mature measurement-technology field.

Filings rose from 4 in 2017 to a peak of 27 in 2020, then declined sharply, with the 2021-to-2024 span showing a -100% change. However, publication typically lags actual filing by around 18 months, so the 2025 and 2026 figures in any dataset are still incomplete and should not be read as a firm decline. Taken together, the pattern looks like a cooling off from an unusually active 2020 rather than an emerging trend, but it is too early to call the field closed.

The overwhelming majority, 90.7% of the 108 records in scope, fall under IPC class G01F, which covers flow, level and volume measuring instruments. A smaller but notable share, 11.1%, also touches G01P (velocity and acceleration measurement), and several other classes — including G01N material analysis, H04M telephonic communication, and container-related classes — appear in low single-digit shares. This tells you calibration innovation is happening mostly inside the core measurement discipline, with only thin activity spilling into adjacent fields.

This 2015 filing describes a method and system for on-site fluid flow meter calibration and verification, notably using standardized Coriolis flow meters as field reference or master meters, tied to compliance with environmental and safety reporting standards. Anyone building an on-site or field-deployable calibration workflow that uses a reference meter in this way should review its claims closely, since it is one of the more heavily cited records in this dataset. Designing around it typically means differentiating the reference-meter type, the verification procedure, or the compliance-reporting integration rather than replicating the same field master-meter approach.

The clearest openings sit outside the dominant G01F class, in areas like automated gravimetric prover systems, in-situ uncertainty statement generation, and predictive recalibration-interval modeling, all of which show some filing activity but no single dominant assignee. Because 90.7% of records sit in G01F alone, sub-4% classes such as G01N and H04M represent genuine but thin adjacent activity worth monitoring before they consolidate. A first claim in these areas would likely combine a core calibration method with a specific automation, prediction or integration element not yet locked up by the leading assignee.