The leading assignee in this dataset holds 114 of the 2,139 records in scope, with the top five combined holding 483 records, or 22.6% of the field. That leaves a substantial long tail: the top ten combined reach 35.5%, meaning most records belong to assignees outside the ranked leaders. The names at the top are dominated by chemical-treatment and process-technology companies rather than traditional HVAC equipment makers, reflecting how much of this field’s claim activity sits in water treatment and fouling control rather than mechanical refrigeration hardware.

Filing moved from 73 records in 2021 to 69 in 2024, a modest 5% decline over the last three-year span that can be treated as complete. The apparent numbers for 2025 and 2026, including a peak of 92 in 2025, should be read cautiously because publication typically lags filing by around 18 months, so recent years are always undercounted at the point of measurement. The honest read is that filing has held roughly steady rather than clearly grown or shrunk over this period.

Water and wastewater treatment (IPC class C02F) leads at 16.5% of the 2,139 records in scope, ahead of refrigeration and heat pumps (F25B) at 13.5% and materials for miscellaneous applications (C09K) at 11.3%. Because a single record can carry several IPC classes, these percentages add up to more than 100% and should be read as claim density per class rather than a breakdown of the field into exclusive segments. The prominence of water-treatment and biocide classes alongside mechanical refrigeration confirms that fouling, scale and corrosion control are core to how this field is actually claimed.