Overview
ISO 20480-2:2018 - "Fine bubble technology - General principles for usage and measurement of fine bubbles - Part 2: Categorization of the attributes of fine bubbles" defines a common framework for describing the physical attributes of fine bubbles in liquids. It establishes descriptors and general principles to report the quality of the liquid medium, size characteristics, number concentration, and classification by rise velocity so users can communicate performance, compare systems, and select appropriate measurement approaches.
Key topics and technical requirements
- Scope and purpose
- Defines general principles and descriptors to describe liquid quality and fine bubble attributes (size, concentration, rise velocity).
- Supports consistent terminology across the ISO 20480 series.
- Liquid medium quality
- Specifies important medium properties to report (e.g., pH, electrical conductivity, total organic carbon, silica, common ionic constituents and optical absorbance at 254 nm) that affect bubble behavior.
- Size index and number concentration index
- Introduces the terms size index and number concentration index (preferred over absolute “size” and “number concentration” to reflect measurement uncertainty).
- Mandatory reporting rules: both indices must be accompanied by the measurement method and the applicable field or sample context.
- Warning: indices from different techniques are not directly comparable and should include an uncertainty statement.
- Dimensional classification
- Recommends categorizing fine bubbles on a size vs. number-concentration matrix (spanning multiple decades) to indicate classes such as ultrafine bubbles.
- Example class: ultrafine bubbles ~0.1–1 µm with number concentrations around 10^6–10^7 per mL.
- Classification by rise velocity
- Defines terminal rise velocity and explains how rise velocity and Brownian motion determine bubble lifetime and transport behavior.
- Notes that rise velocity depends on diameter, viscosity, boundary conditions and bubble interactions and that very low-rise-velocity bubbles can remain suspended for long periods.
Practical applications and users
- Who uses it: researchers, equipment manufacturers, test laboratories, water treatment engineers, aquaculture specialists, agriculture/horticulture technologists, and developers of fine-bubble applications in food, cosmetics, pharmaceuticals, and materials processing.
- Practical value:
- Standardizes reporting to support product claims, performance comparisons and regulatory or procurement specifications.
- Guides selection of measurement methods (e.g., particle tracking analysis) and sample reporting so stakeholders can assess bubble performance in processes such as dissolved-gas transfer, flotation/separation, cleaning, and enhanced mass transfer.
Related standards
- ISO 20480-1 (Terminology)
- ISO 19430 (Particle tracking analysis - referenced as an example method)
- Water quality references: ISO 3696, ASTM D1193, CODEX STAN 108
Keywords: ISO 20480-2:2018, fine bubble technology, fine bubbles, ultrafine bubbles, size index, number concentration index, rise velocity, measurement, classification, liquid medium quality.
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