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

This document establishes the general principles and descriptors to allow users to describe the quality of the liquid media and the size and concentration of fine bubbles. It is also intended to allow users to classify fine bubbles by rise velocity.

Technologie des fines bulles — Principes généraux pour l'utilisation et la mesure des fines bulles — Partie 2: Classification des attributs des fines bulles

General Information

• Status: Published
• Publication Date: 14-Nov-2018
• ICS: 07.030 - Physics. Chemistry
• Technical Committee: ISO/TC 281 - Fine bubble technology
• Drafting Committee: ISO/TC 281/WG 1 - General principles including terminology
• Current Stage: 9093 - International Standard confirmed
• Start Date: 28-Oct-2024
• Completion Date: 13-Dec-2025

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.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 20480-2
First edition
2018-11
Fine bubble technology — General
principles for usage and measurement
of fine bubbles —
Part 2:
Categorization of the attributes of
fine bubbles
Technologie des fines bulles — Principes généraux pour l'utilisation et
la mesure des fines bulles —
Partie 2: Classification des attributs des fines bulles
Reference number
©
ISO 2018
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
ii © ISO 2018 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General principles for usage and measurement of fine bubbles . 1
4.1 Standards system of fine bubble technology . 1
4.2 Quality of liquid medium. 2
5 Expression of attributes for fine bubbles . 2
5.1 Application of size index and number concentration index . 2
5.1.1 General. 2
5.1.2 Size index rules . 3
5.1.3 Number concentration principles . 3
5.1.4 Number concentration index rules . 3
5.2 Expression of class of fine bubbles in dimensional characteristics . 3
6 Classification of the attributes of fine bubbles by rise velocity . 4
6.1 Attributes of fine bubbles by rise velocity . 4
6.2 Classification of fine bubbles by rise velocity. 5
6.2.1 General. 5
6.2.2 Classification and definition of regions . 6
Annex A (informative) Observation examples of ultrafine bubble number stability in liquids .8
Bibliography .10
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
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constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 281 Fine bubble technology.
A list of all parts in the ISO 20480 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2018 – All rights reserved

Introduction
In recent years, readily available measurement techniques of bubbles have made it possible to
characterize microbubbles and ultrafine bubbles. Such techniques have shown that ultrafine bubbles
can almost remain as they are for a number of months.
Fine bubble technologies are very new, and their applications are useful in a number of fields today.
Developing appropriate terminology for such a diverse area of technology is therefore critical to
business trade or product acceptance, in view of the wide range of users of fine bubbles.
For better communication among the users of fine bubbles, this document introduces the quality criteria
of a medium such as water, as well as two indices, one for size and the other for number concentration.
This document also provides an explanation for classifying fine bubbles by dimensional characteristics
and by rise velocity.
It should be noted that the motion of bubbles in a medium can be determined by buoyancy forces
or randomly and thermally activated processes leading to Brownian motion. For this reason, larger
bubbles can display buoyant behaviour (rise upwards) and smaller bubbles remain in the liquid medium
displaying random motion. This document focuses on the definitions of such entities.
INTERNATIONAL STANDARD ISO 20480-2:2018(E)
Fine bubble technology — General principles for usage and
measurement of fine bubbles —
Part 2:
Categorization of the attributes of fine bubbles
1 Scope
This document establishes the general principles and descriptors to allow users to describe the quality
of the liquid media and the size and concentration of fine bubbles. It is also intended to allow users to
classify fine bubbles by rise velocity.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 20480-1, Fine bubble technology — General principles for usage and measurement of fine bubbles —
Part 1: Terminology
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 20480-1 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
rise velocity
velocity of a fine bubble upwards in liquid
3.2
terminal rise velocity
balancing velocity between the buoyancy of fine bubbles and the viscous drag
Note 1 to entry: It is the velocity in the opposite direction to the terminal settling velocity. If a rise velocity were
to be defined as the terminal settling velocity, the rise velocity would be negative. Therefore, in the classification
of fine bubbles, terminal rise velocity is preferred over terminal settling velocity to avoid confusion.
4 General principles for usage and measurement of fine bubbles
4.1 Standards system of fine bubble technology
The purpose of this document is to provide people who develop standards for fine bubble technology
with an overall framework and guidelines, and to facilitate communication among users of fine
bubbles. To assist in the preparation of consistent standards, a three-layered standard system has been
established.
This consists of the following.
a) The first layer (basic standards) covers common terminology, basic concepts, and principles for
measurement and usage that can be applied to fine bubble technology. This document is part of the
basic standards, and is intended to be used as a basis for the next two layers.
b) The second layer (measurement standards) covers various measurement methodologies for
characterization, such as bubble diameter and number concentration index, as well as common
methods for sampling and sample preparation.
c) The third layer (individual application standards) covers individual applications in areas
including:
1) food, plant cultivation, agriculture, drinking water, and cosmetics industries;
2) the medical and pharmaceutical fields;
3) manufacturing of new functional materials, solar cells, semiconductors, and liquid crystals;
4) processes such as cleaning, toilet flushing, soil washing, water treatment, etc.
4.2 Quality of liquid medium
The performance of the liquid medium with
...