ISO 7428-1:2024

Fine bubble technology — Domestic applications — Part 1: Assessment of showerhead devices by evaluating size and concentration indices of generated fine bubbles

This document specifies the evaluation method for size and concentration indices of fine bubbles generated from the fine bubble showerhead device. It is only applicable to fine bubble dispersion in water generated from fine bubble showerhead devices using air. It describes the sampling method for fine bubble dispersion in water from the fine bubble showerhead devices into the retention container and the measurement procedure of size and concentration indices. NOTE The discharging drive force for fine bubble showerhead devices is applied using a pump or water pressure. Therefore, the test of the subject device is performed under environmental conditions including such a practical environment.

Technologie des fines bulles — Applications domestiques — Partie 1: Évaluation des dispositifs avec pommes de douche par évaluation des indices de concentration et de la taille des fines bulles générées

General Information

• Status: Published
• Publication Date: 21-May-2024
• ICS: 07.030 - Physics. Chemistry
• Technical Committee: ISO/TC 281 - Fine bubble technology
• Drafting Committee: ISO/TC 281 - Fine bubble technology
• Current Stage: 6060 - International Standard published
• Start Date: 22-May-2024
• Due Date: 22-Apr-2025
• Completion Date: 22-May-2024

Standards Content (Sample)

International
Standard
ISO 7428-1
First edition
Fine bubble technology — Domestic
2024-05
applications —
Part 1:
Assessment of showerhead
devices by evaluating size and
concentration indices of generated
fine bubbles
Technologie des fines bulles — Applications domestiques —
Partie 1: Évaluation des dispositifs avec pommes de douche par
évaluation des indices de concentration et de la taille des fines
bulles générées
Reference number
© ISO 2024
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements . 2
4.1 Sample .2
4.2 Measuring instruments .2
5 Environment . 2
6 Evaluation . 2
6.1 General .2
6.2 Setting of fine bubble showerhead device to retention container .3
6.3 One-way flow .4
6.3.1 General .4
6.3.2 System configuration .4
6.3.3 Evaluation procedure for the one-way flow .5
6.4 Circulation flow .6
6.4.1 General .6
6.4.2 System configuration .6
6.4.3 Evaluation procedure for the circulation flow .7
7 Test report . 8
Annex A (informative) Example of results for microbubbles using the one-way flow . 9
Annex B (informative) Example of results for ultrafine bubbles using the circulation flow .10
Annex C (informative) Water service standards for water pressure in different countries .11
Annex D (informative) Example of test systems to evaluate the showerhead device .12
Annex E (normative) Test report requirements for conformity assessment application . 14
Bibliography .15

iii
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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.
A list of all parts in the ISO 7428 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
Introduction
Fine bubble technology has recently seen growth in its application to markets such as cleaning, water
treatment, agriculture, aquaculture and biomedical fields. To clarify the efficacy and the efficiency of
fine bubbles, the characteristics of fine bubbles should be evaluated accurately. The most important
characteristics of fine bubbles are the number or volume concentration and size indices of the fine bubbles
produced by the fine bubble generating systems.
Above all, fine bubble showerhead devices have been extensively used as most popular fine bubble
generating devices at home. Therefore, standardization of evaluation for fine bubble showerhead device
should be accelerated to maintain the reputation of fine bubble technology as an advanced technology used
for consumer products all over the world.
The evaluation method for size and concentration indices of fine bubbles is the basis for fair and appropriate
business of fine bubble showerhead devices, which can introduce the dissemination of fine bubble products.

v
International Standard ISO 7428-1:2024(en)
Fine bubble technology — Domestic applications —
Part 1:
Assessment of showerhead devices by evaluating size and
concentration indices of generated fine bubbles
1 Scope
This document specifies the evaluation method for size and concentration indices of fine bubbles generated
from the fine bubble showerhead device. It is only applicable to fine bubble dispersion in water generated
from fine bubble showerhead devices using air. It describes the sampling method for fine bubble dispersion
in water from the fine bubble showerhead devices into the retention container and the measurement
procedure of size and concentration indices.
NOTE The discharging drive force for fine bubble showerhead devices is applied using a pump or water pressure.
Therefore, the test of the subject device is performed under environmental conditions including such a practical
environment.
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, 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
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 showerhead device
device driven by the outer water pressure and applied to discharge fine bubble dispersion in water into the
air or water in the form of a spray or shower of water droplets

4 Requirements
4.1 Sample
To reduce the influence of particulate contaminants and to keep the accuracy of measurement, the fine
bubble dispersions in water used to test fine bubble showerhead devices shall be generated using cleaned
test systems with clean water and clean air.
The purity level of water and air depends on the purpose of the test.
The fine bubble dispersion shall not contain stabilizing agents such as surfactants.
If the measurement accuracy of size and concentration indices is very important (for example, in the case of
application to the accreditation of fine bubble business), the water purity level of ISO Grade 1 (see ISO 3696)
and the air cleanliness of ISO Class 5 (see ISO 14644-1) are recommended for the water and the air used for
generating the fine bubble dispersion (FBD).
4.2 Measuring instruments
When the measuring instruments are selected for evaluating the size and concentration indices of fine
bubbles generated from showerhead device, the following requirements for the concentration and the size
range shall be considered. These requirements depend on the characteristics of the sample to be evaluated.
a) The total number concentration and total volume concentration of the entire sample generated from
the fine bubble showerhead devices including fine bubbles and contaminants (solid and liquid particles)
shall be measured. Raw water can be used for diluting the FBD when the concentration is too high for
the measurement technique in question.
b) The size range of the entire sample including fine bubbles, contaminants and aggregates of contaminants
shall be measured. Different measuring instruments can be used to confirm the larger aggregates.
NOTE The particle tracking analysis method can be used for evaluation of number concentration, and the laser
diffraction method can be used for the 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 air cleanliness should be considered for the measurement to prevent the introduction of impurities.
Ambient temperature and atmospheric pressure should be stable to maintain the stability of the size and
concentration of fine bubbles.
Air cleanliness, ambient temperature and atmospheric pressure depend on the local environment and can
vary. However, as they are important settings and can influence the evaluation process, they should be
recorded prior to any evaluation occurring.
If the measurement accuracy of size and concentration indices is very important, (for example, in the case of
application to the accreditation of fine bubble business), the air cleanliness of ISO Class 7 (see ISO 14644-1)
is recommended as the environment for generation and measurement of a FBD in water.
6 Evaluation
6.1 General
When evaluating the size and concentration indices of fine bubbles generated from the fine bubble showerhead
device, the one-way flow configuration shall be used. However, the circulation flow configuration shall be
used in the case that signal from UFB is too low to measure because of the low concentration of UFB.

6.2 Setting of fine bubble showerhead device to retention container
As shown in Figure 1, the fine bubble showerhead device shall be set to fix all the discharge holes of the
fitted showerhead device so that they are submerged below the water surface. The water surface level can
be maintained by overflow from retention container.
To prevent the destruction of fine bubbles by collision, sufficient distance is necessary between the d
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