ISO 24261-1:2020
(Main)Fine bubble technology — Elimination method for sample characterization — Part 1: Evaluation procedure
Fine bubble technology — Elimination method for sample characterization — Part 1: Evaluation procedure
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.
Technologie des fines bulles — Méthode d'élimination pour la caractérisation de l'échantillon — Partie 1: Mode opératoire d'évaluation
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INTERNATIONAL ISO
STANDARD 24261-1
First edition
2020-11
Fine bubble technology — Elimination
method for sample characterization —
Part 1:
Evaluation procedure
Technologie des fines bulles — Méthode d'élimination pour la
caractérisation de l'échantillon —
Partie 1: Mode opératoire d'évaluation
Reference number
©
ISO 2020
© ISO 2020
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Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements . 1
4.1 Sample . 1
4.2 Measuring instruments . 2
5 Environment . 2
6 Evaluation of fine bubble elimination efficiency . 2
6.1 General . 2
6.2 Reduction rate . 2
6.3 Confirmation of contaminants aggregation . 3
6.4 E valuation procedure of fine bubble elimination . 3
7 Test report . 4
7.1 Report of the testing results . 4
7.2 Report of the testing conditions . 4
Annex A (informative) Simulations of fine bubble elimination process . 5
Annex B (informative) Decrease of concentration caused by fine bubble elimination and
aggregation . 7
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
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iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 281 Fine bubble technology.
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.
iv © ISO 2020 – All rights reserved
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. Especially characteristics like the number concentration index and
the size index of fine bubbles are indispensable for those evaluations.
Furthermore, fine bubble dispersion water may contain other solid and liquid particles. Clearly due to
this is a concern, as it may be impossible to evaluate the characteristics of fine bubbles. Therefore, it is
an urgent task to address this concern.
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. If most of fine bubbles decreased, a solution that doesn’t have them can
be used as a blank solution for measurements as background. Because it is expected that fine bubbles
elimination techniques will develop further, standardizing elimination techniques and evaluation
method is required.
This document is intended to specify the evaluation method for elimination efficiency of fine bubbles
from fine bubble dispersions in water.
Standardization for evaluating elimination efficiency of fine bubbles enables easy and clear comparison
among the several elimination techniques and realizes the optimization of conditions for respective
elimination techniques.
INTERNATIONAL STANDARD ISO 24261-1:2020(E)
Fine bubble technology — Elimination method for sample
characterization —
Part 1:
Evaluation procedure
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
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
elimination of fine bubbles
process for decrease of the concentration index of fine bubbles
3.2
fine bubble dispersion
FBD
liquid which contains fine bubbles
[SOURCE: ISO 20298-1:2018, 3.1]
4 Requirements
4.1 Sample
The fine bubble dispersion to be evaluated shall be generated by cleaned fine bubble generating systems
using pure water and pure gas such as air, nitrogen and oxygen.
The purity level of water and gas depends on the sample whose size and concentration indices of
fine bubbles should be evaluated because fine bubble elimination is one of the evaluating process for
specified samples. So, the purity level cannot be generally determined as measurement condition for
evaluations of the elimination efficiency.
The fine bubble dispersion shall not contain stabilizing agents.
If the measurement accuracy of size and concentration indices is very important (e.g. for accreditation
purposes), a water purity level of Grade 1 according to ISO 3696 is recommended for the water used for
generation of FBD.
4.2 Measuring instruments
When the measuring instruments are selected for evaluating fine bubble elimination for FBD in water
the following parameters about concentration and size range shall be confirmed, which depends on the
characteristics of the sample to be evaluated.
a) Total number concentration and/or total volume concentration including fine bubbles and
contaminants such as solid particles and liquid particles can be measured. Water diluent can be
used for diluting the FBD in water when the concentration is over the measuring range.
b) Total size range including fine bubbles, contaminants and aggregates of contaminants can be
measured. Another measuring instrument can be used to confirm the larger aggregates.
EXAMPLE Particle tracking analysis method can be used for evaluation of number concentration, and laser
diffraction method can be used for evaluation of volume concentration. ISO/TR 23015 can be referred to for
details of measurement techniques which can be used for FBD in water.
5 Environment
The classification of air cleanliness should be applied for the measurements to prevent any
contamination by impurities. Ambient temperature and atmospheric pressure should be stable to keep
the stability of ultrafine bubbles.
Air cleanliness, ambient temperature and atmospheric pressure depend on the environment to
evaluating size and concentration indices of specified samples because fine bubble elimination is
one of the evaluating process for specified samples. Therefore, the environment cannot be generally
determined for evaluations of the elimination efficiency.
If the measurement accuracy of size and concentration indices is very important (e.g. for accreditation
purposes), the air cleanliness of ISO Class 7 as defined in ISO 14644-1 is recommended as the
environment of generation and measurement of FBD in water.
6 Evaluation of fine bubble elimination efficiency
6.1 General
Fine bubbles can be eliminated from fine bubble dispersion in water using some techniques such as
ultrasonication method, ultracentrifugal fractionation and freezing method. If most of the fine bubbles
can be eliminated from fine bubble dispersion in water, this water can be used for blank water.
6.2 Reduction rate
The elimination efficiency should be evaluated using the number reduction rate and volume reduction
rate, which are defined respectively by Formula (1) and Formula (2).
rq=−()qq/ ×100 (1)
00,,ba00,b
where
2 © ISO 2020 – All rights reserved
r is the number reduction rate (%);
q
is the number concentration index in the specified size range after elimination process;
0,a
q is the number concentration index in the specified size range before elimination process.
0,b
rq=−()qq/ ×100 (2)
33,,ba33,b
where
r is the volume r
...
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