National foreword

This British Standard is the UK implementation of ISO 24261‑1:2026. It supersedes BS ISO 24261‑1:2020, which is withdrawn.

The UK participation in its preparation was entrusted to Technical Committee LBI/50, Fine Bubble Technology (FBT).

A list of organizations represented on this committee can be obtained on request to its committee manager.

Contractual and legal considerations

This publication has been prepared in good faith, however no representation, warranty, assurance or undertaking (express or implied) is or will be made, and no responsibility or liability is or will be accepted by BSI in relation to the adequacy, accuracy, completeness or reasonableness of this publication. All and any such responsibility and liability is expressly disclaimed to the full extent permitted by the law.

This publication is provided as is, and is to be used at the recipient’s own risk.

The recipient is advised to consider seeking professional guidance with respect to its use of this publication.

This publication is not intended to constitute a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 November 2026.

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 through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. 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).

Any trade name used in this document is information given for the convenience of users and does not 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.

This second edition cancels and replaces the first edition (ISO 24261‑1:2020), of which it constitutes a minor revision.

The changes are as follows:

in 7.1, the following list item was added "f) Number of this document";
in Figure A.1 and Figure A.2, the unit "million/ml" was revised to "×10⁶ particles/ml".

A list of all parts in the ISO 24261 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.

Introduction

Fine bubble technology has recently seen growth in its application to markets in cleaning, water treatment, agriculture, and aquaculture as well as biomedical fields. Now, methods are required to evaluate the generation systems. Characteristics like number concentration index and the size index of fine bubbles are especially indispensable for those evaluations.

Furthermore, fine bubble dispersion water may contain other solid and liquid particles. Due to this concern, it may be impossible to evaluate the characteristics of fine bubbles. Therefore, a method to address the presence of other particles is urgently needed.

There are several measurement methods widely used to evaluate the number concentration index and the size index of particles. However, there are few methods to distinguish bubbles in fine bubble dispersions from other particles.

This issue can be resolved, using the phenomenon by which the bubbles can be eliminated without any residues after dissolution and flotation. If a method that eliminates fine bubbles in specific size range is known, it is possible to distinguish fine bubbles from other solid and liquid particles. The eliminated particles can be fine bubbles. A solution in which fine bubbles are not present or have been almost completely removed can be used as a blank solution for background measurements. Standardizing elimination techniques and evaluation methods are required as fine bubble elimination techniques will continue to develop further.

This document is intended to specify the evaluation method for elimination efficiency of fine bubbles from fine bubble dispersions in water.

A standard method to evaluate fine bubble elimination efficiency enables easy and clear comparison among several techniques and presents optimal conditions for respective elimination techniques.

1 Scope

This document specifies the evaluation procedure of fine bubble elimination for fine bubble dispersion in water. This document is applicable only to fine bubbles without shell.

2 Normative references

3 Terms and definitions

4 Requirements

4.1 Sample

4.2 Measuring instruments

5 Environment

6 Evaluation of fine bubble elimination efficiency

6.1 General

6.2 Reduction rate

6.3 Confirmation of contaminants aggregation

6.4 Evaluation procedure of fine bubble elimination

7 Test report

7.1 Report of the testing results

7.2 Report of the testing conditions

Bibliography