ISO/FDIS 20480-3

FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 20480-3
ISO/TC 281
Fine bubble technology — General
Secretariat: JISC
principles for usage and measurement
Voting begins on:
2021-06-24 of fine bubbles —
Voting terminates on:
Part 3:
2021-08-19
Methods for generating fine bubbles
Technologie des fines bulles — Principes généraux pour l'utilisation et
la mesure des fines bulles —
Partie 3: Méthodes pour générer des fines bulles
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 20480-3:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. ISO 2021
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ISO/FDIS 20480-3:2021(E)
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© ISO 2021

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Foreword ........................................................................................................................................................................................................................................iv

Introduction ..................................................................................................................................................................................................................................v

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Examples of methods for generating fine bubbles ............................................................................................................ 3

4.1 Swirling flow system (for microbubble generation) .............................................................................................. 3

4.2 Static mixer system (for microbubble generation).................................................................................................. 3

4.3 Ejector system ......................................................................................................................................................................................... 4

4.4 Venturi system ......................................................................................................................................................................................... 5

4.5 Pressurized dissolution system (for microbubble generation) .................................................................... 6

4.6 Mechanical shear system ............................................................................................................................................................... 7

4.7 Micropore system ................................................................................................................................................................................. 8

4.8 Surfactant addition micropore system ............................................................................................................................... 9

4.9 Microporous shear system.........................................................................................................................................................10

4.10 Heat separation system ................................................................................................................................................................11

4.11 Mixed vapor condensation system .....................................................................................................................................12

4.12 Swirling flow system (for ultra fine bubble generation) .................................................................................12

4.13 Pressurized dissolution system (for ultra fine bubble generation) .......................................................13

4.14 Static mixer system (for ultra fine bubble generation) .....................................................................................14

4.15 Electrolytic system ............................................................................................................................................................................15

4.16 Ultrasound (cavitation) system .............................................................................................................................................16

4.17 Other methods ......................................................................................................................................................................................17

Annex A (informative) Other examples of methods for generating fine bubbles ...............................................18

Bibliography .............................................................................................................................................................................................................................19

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Any feedback or questions on this document should be directed to the user’s national standards body.

Until now the terminology, method and corresponding technology for the generation of fine bubbles

have not been standardized. The new project to standardize the terminology of fine bubble generating

systems and the corresponding technology is thought to have significant influences on the market as

— convenience of customers when purchasing or using fine bubble generating system and its techniques

will be improved, and owing to the improvement of their convenience, it can be expected to boost

— standardization of terminology will enhance commonality in the field of generating system

performance. Improvement in performances in hardware and software will also prospectively lead

to market growth of the manufacturing industries of fine bubble generating system;

— standardization of terminology will enable the application markets to be boosted in creating new

In addition to existing fine bubble technology standards, by specifying "common terms" of generation

principles, it will allow best practices to use common terms for fine bubble generating systems as well

The following documents are referred to in the text in the sense 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 —

ISO 20480-2, Fine bubble technology — General principles for usage and measurement of fine bubbles —

For the purposes of this document, the terms and definitions given in ISO 20480-1 and ISO 20480-2,

ISO and IEC maintain terminological databases for the use in standardization at the following addresses:

formation and collapse of bubbles in a liquid when the pressure falls to or below the liquid vapour

pressure, the collapse releases energy, sometimes with an audible sound and vibration

device which consists of a convergent inlet which is conically connected to the cylindrical part called

spinning disc in a centrifugal pump with protruding vanes, which is used to accelerate the fluid in the

maximum mass of a solute that can be dissolved in a unit volume of solution measured under equilibrium

high frequency (over 20 kHz) sound waves which propagate through fluids and solids

air and/or other gases which is not liquefied under the conditions of a saturated steam

Note 1 to entry: In the case of water, the separation of hydrogen from oxygen is taken as an example.

Liquid is made to swirl around the interior of a cylinder at a high speed, reducing the pressure near

the central axis of the cylinder and thereby causing gas to be sucked in from the outside. Within the

cylinder, centrifugal separation occurs where low-density gas is located at the centre and high-density

liquid is located at the cylinder wall. The gas column is pulverized by the fierce shear flow to produce

Figure 1 — Schematic diagram of fine bubble generation using swirling flow system

This system does not use mechanical pulverization. The flow path has a complex structure, and the

circulatory drive force of the liquid produces a vortex flow which is primarily responsible for creating a

large viscous shear force that pulverizes the gas. Protrusions on the inner wall of the cylinder produce

vortex in the liquid flow, and the large bubbles carried along with the liquid are pulverized by the shear