ISO 24218-1:2023
(Main)Fine bubble technology — Characterization of fine bubbles — Part 1: Evaluation of size and concentration indices by laser diffraction method
Fine bubble technology — Characterization of fine bubbles — Part 1: Evaluation of size and concentration indices by laser diffraction method
This document specifies the evaluation of fine bubbles size and concentration indices applied to the combined use of number-based size analysis and volume-based size analysis by the laser diffraction method. The methodology described is appropriate to both bimodal and multimodal samples over a broad size range (from tens of nanometers to tens of micrometers) and applies to ultrafine bubble and microbubble dispersions (MBD) and mixtures thereof.
Technologie des fines bulles — Caractérisation des fines bulles — Partie 1: Évaluation des indices de concentration et de taille par diffraction laser
General Information
Standards Content (Sample)
INTERNATIONAL ISO
STANDARD 24218-1
First edition
2023-02
Fine bubble technology —
Characterization of fine bubbles —
Part 1:
Evaluation of size and concentration
indices by laser diffraction method
Technologie des fines bulles — Caractérisation des fines bulles —
Partie 1: Évaluation des indices de concentration et de taille par
diffraction laser
Reference number
ISO 24218-1:2023(E)
© ISO 2023
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ISO 24218-1:2023(E)
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© ISO 2023
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ISO 24218-1:2023(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Test requirements . 2
4.1 Sample . 2
4.2 Measuring instrument . 2
4.3 Environment . 2
5 Number concentration and volume concentration . 2
5.1 Difference of impression between number-based and volume-based size
distributions . 2
5.2 Conversion between number dimension amount and volume dimension amount . 4
5.3 Evaluation of fine bubble effect . 5
6 Evaluation . 5
6.1 Sampling and sample preparation . 5
6.2 Procedure of the combined use of number-based size analysis and volume-based
size analysis by laser diffraction method . 5
7 Test report . 6
Annex A (informative) Examples of combined use of number-based size analysis and
volume-based size analysis by laser diffraction method . 7
Bibliography .11
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ISO 24218-1:2023(E)
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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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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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 24218 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.
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ISO 24218-1:2023(E)
Introduction
Fine bubble technology has seen growth in its application to markets such as cleaning, water treatment,
agriculture, aquaculture and biomedical fields. Now the methods to evaluate the characteristics of fine
bubbles such as the size and concentration indices become necessary to clarify the performances of fine
bubble generating systems used for various applications.
The shape of the size distribution of fine bubble dispersions (FBD) can be bimodal or multimodal, and
this distribution can extend broadly from ultrafine bubble (UFB) range to microbubble (MB) range.
To evaluate the relationship between the characteristics of fine bubbles and their effects, it should
be considered that the respective modes of multimodal size distribution can have their independent
contributions to the total performance of fine bubbles.
The laser diffraction method can evaluate multimodal size distributions from the range of UFB (<1 μm)
to that of MB (on the micron scale).
Due to the nature of number-based size distribution, any examination of a sample on a number basis
which mixes populations of ultrafine and micro bubbles is unduly weighted to the fraction of smaller
size bubbles (ultrafine bubbles). The important fraction of larger size bubbles (micro bubbles) can
therefore be lost. At the viewing of size distribution data, the confirmation of its dimension (number
basis or volume basis) is necessary. Moreover, the suitability of approach about the dimension of size
distribution should be taken into consideration in terms of what it can do to the size distribution and
what is the most appropriate approach for the application under evaluation.
This document is intended to specify the evaluation of fine bubbles size and concentration indices
by combined use of number-based size analysis and volume-based size analysis by laser diffraction
method. Both bimodal and multimodal samples are appropriate. It is applicable to fine bubbles with and
without shell over a size range which includes UFB and MB dispersions and any combination thereof.
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INTERNATIONAL STANDARD ISO 24218-1:2023(E)
Fine bubble technology — Characterization of fine
bubbles —
Part 1:
Evaluation of size and concentration indices by laser
diffraction method
1 Scope
This document specifies the evaluation of fine bubbles size and concentration indices applied to the
combined use of number-based size analysis and volume-based size analysis by the laser diffraction
method. The methodology described is appropriate to both bimodal and multimodal samples over a
broad size range (from tens of nanometers to tens of micrometers) and applies to ultrafine bubble and
microbubble dispersions (MBD) and mixtures thereof.
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
ISO 20298-1:2018, Fine bubble technology — Sampling and sample preparation for measurement — Part
1: Ultrafine bubble dispersion in water
ISO 21910-1, Fine bubble technology — Characterization of microbubbles — Part 1: Off-line evaluation of
size index
ISO 13320, Particle size analysis — Laser diffraction methods
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 terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
fine bubble dispersion
FBD
liquid which contains fine bubbles
[SOURCE: ISO 20298-1:2018, 3.1]
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ISO 24218-1:2023(E)
3.2
ultrafine bubble dispersion
UFBD
liquid which contains ultrafine bubbles
[SOURCE: ISO 20298-1:2018, 3.3]
3.3
microbubble dispersion
MBD
liquid which contains microbubbles
[SOURCE: ISO 20298-1:2018, 3.4]
4 Test requirements
4.1 Sample
The fine bubble dispersion (FBD) to be evaluated shall be generated by the use of a clean fine bubble
generating system using pure water and pure gas such as air, nitrogen or oxygen.
4.2 Measuring instrument
A measuring instrument based on the laser diffraction method shall be used to evaluate the size and
concentration indices of the FBD in water. The laser diffraction method can evaluate broad multimodal
size distributions from the range of UFB to that of MB. It can be applicable for the combined use of the
number-based size analysis and the volume-based size analysis for a sample whose size distribution is
bimodal or multimodal in this size range.
The size distribution obtained from measurement is generally expressed showing the relationship
between the size and the normalized volume concentration (%). The size distribution between the
size and the normalized number concentration (%) can be obtained easily using the software attached
with the instrument. This number-based size distribution can also be calculated using a spreadsheet
software such as Excel.
Note Some instruments can obtain the size distribution between the size and the volume concentration
(μl/ml) and the size distribution between the size and the number concentration (number/ml) as shown
in Annex A. Similar data processing using the measured data from general instruments to obtain the size
distribution of size and concentration can be realized using the spreadsheet software but it is not so easy for
general users, without the support of the manufacturer.
Laser diffraction methods shall conform to ISO 13320.
4.3 Environment
The classification of air cleanliness should be applied for the measurement to prevent the contamination
from impurities. Ambient temperature and atmospheric pressure should be stable to prevent the
change of fine bubbles characteristics.
5 Number concentration and volume concentration
5.1 Difference of impression between number-based and volume-based size
distributions
The measurement result of a number-based size analysis can be very different from that of a volume-
based s
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