This dataset tracks 21,273 published records filed between 2015 and mid-2026 that combine data center liquid cooling terminology with retrofit-specific signals such as coolant distribution units, facility water loops, and leak detection. The count includes both dedicated liquid-cooling hardware filings and the air-cooling baseline claims that retrofit approaches interact with. Because publication lags filing by roughly 18 months, the most recent year in that range is understated and will rise as more applications publish.

The ranking covers 100 assignees, with the leader holding 337 records against the 21,273-record corpus. Concentration is low: the top 5 assignees combined account for only 6.9% of all records in scope, and the top 10 reach 11.8%. That spread means the field is being worked by a mix of refrigerant chemistry firms, HVAC hardware makers, and diversified electronics conglomerates rather than a small set of specialists holding a dominant position.

Filing volume rose from 837 records in 2017 to a peak of 1,387 in 2023, but the 2022 midpoint of 1,330 shows the growth curve had already flattened before that peak. Several of the largest tracked assignees show zero filings or year-on-year declines as steep as -100% in the most recent tracked year. Combined with the 18-month publication lag on the partial 2026 figure, the pattern reads as a maturing filing base rather than an accelerating one.

US11326798B2 claims a refrigerant leak detection and mitigation system that pairs a refrigerant gas sensor with a signal conditioner, alarm indicator, and digital control processor arranged in a closed control loop that continuously recalibrates for background gas levels and ambient conditions. It is a specific closed-loop recalibration architecture, not a claim over refrigerant leak sensing generally. Designs that detect leaks without that particular dynamic recalibration loop, or that use a different feedback architecture between sensor and controller, sit outside its literal claim scope, though a freedom-to-operate review should still check the full claim set and file history.

Relative to the dense instrumentation and testing classes — G01M alone touches 19.5% of the 21,273 records — narrower retrofit-specific mechanics show thinner coverage in this corpus: phased migration sequencing controls, cross-vendor coolant distribution unit interoperability, and mixed air/liquid rack density transition logic. These are candidate areas for a first-mover claim, though thin coverage in a keyword-based search should be confirmed with a targeted prior-art search before drafting, since it can also reflect classification or terminology gaps rather than true white space.