ISO 21256-3:2021

Fine bubble technology - Cleaning applications - Part 3: Test method for cleaning hard flooring surfaces

This document specifies a test method for the cleaning of hard flooring surfaces. It can be used to demonstrate the comparative cleaning performance of a fine bubble solution to an alternate cleaning solution to remove contaminant from a soiled surface. This alternate cleaning solution can be another fine bubble solution, municipal tap water or a commercially available cleaning solution blended to the manufacturer’s specifications. This method is not suitable for differentiating between cleaning solutions when the contaminant is excessively applied on the surface as the mechanism of cleaning changes.

Technologie des fines bulles — Applications de nettoyage — Partie 3: Titre manque

General Information

• Status: Published
• Publication Date: 29-Jul-2021
• ICS: 07.030 - Physics. Chemistry
• Technical Committee: ISO/TC 281 - Fine bubble technology
• Drafting Committee: ISO/TC 281/WG 3 - Applications of fine bubble technology
• Current Stage: 6060 - International Standard published
• Start Date: 30-Jul-2021
• Due Date: 28-Feb-2022
• Completion Date: 30-Jul-2021

Relations

• Consolidated By: ISO 4491-2:2023 - Metallic powders - Determination of oxygen content by reduction methods - Part 2: Loss of mass on hydrogen reduction (hydrogen loss)
• Effective Date: 06-Jun-2022

Overview

ISO 21256-3:2021 - Fine bubble technology: Test method for cleaning hard flooring surfaces defines a repeatable laboratory method to evaluate the cleaning performance of fine bubble solutions versus alternative cleaning fluids (another fine bubble solution, municipal tap water, or a commercial cleaner). The standard describes apparatus modifications, a standardized test soil and deposition method, test-piece preparation, measurement procedures and a cleaning-index calculation to quantify soil removal.

Key topics and technical requirements

• Test principle: Measure mass loss of residual contaminant to calculate a cleaning index (E = (Ms − Mc) / (Ms − Mi), where Mi = initial mass, Ms = mass with soil, Mc = mass after cleaning).
• Apparatus: Uses a modified reciprocating scrub test machine with a hydraulic atomizing nozzle (hollow-cone spray, ~70° angle, ~1 mm orifice). Nozzle travel and spray geometry are specified to ensure consistent coverage.
• Flow, pressure and temperature: Typical settings include outlet flow 0.23 ± 0.02 L/min, supply tap-water flow ~0.45 ± 0.05 L/min, and nozzle pressure 200 kPa ± 10 kPa. Cleaning liquid temperature: 20 °C to 26 °C ± 1 °C.
• Test pieces and soil: Test tiles: uncoated vinyl composite, 300 mm × 150 mm (±10 mm). Surface soil density target 28 mg/cm². Test soil formulation (Annex A) lists specific ingredients (mineral/hydraulic oils, clays, red iron oxide, wood flour) and deposition using a doctor blade/stencil method.
• Measurement accuracy: Mass determined with resolution 0.01 g or better; cleaned tiles dried to constant mass (or ≥3 h at ≈45 °C) before weighing.
• Test limitations: Not suitable when contaminant is excessively applied-mechanism of cleaning changes and results are not differentiating.

Applications and practical value

• Provides a standardized, comparable laboratory method to:
  • Quantify and compare cleaning efficacy of fine bubble generators, water-only systems and chemical cleaners on hard floors.
  • Support product development and performance claims for industrial or commercial cleaning equipment (e.g., walk-behind floor cleaners, automated scrubbers).
  • Reduce chemical usage by validating fine bubble solutions as alternatives, contributing to sustainability goals (reduced chemicals, lower energy/carbon footprint).
• Useful in R&D, quality control, third‑party testing, procurement specifications and regulatory/market-claim substantiation.

Who should use this standard

• Manufacturers of fine bubble generators and cleaning equipment
• Flooring manufacturers and materials test labs
• Building services, janitorial product developers, and independent testing laboratories
• Procurement teams and regulators seeking objective performance metrics

Related standards

• ISO 20480-1 - Fine bubble technology: terminology and general principles for usage and measurement (normative reference).
• See other parts of the ISO 21256 series for broader fine bubble technology guidance.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 21256-3
First edition
2021-07
Fine bubble technology — Cleaning
applications —
Part 3:
Test method for cleaning hard flooring
surfaces
Reference number
©
ISO 2021
© ISO 2021
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
ISO copyright office
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Phone: [phone]
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Published in Switzerland
ii © ISO 2021 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus . 2
5.1 Test equipment . 2
5.2 Determination of soil removal . 3
6 Preparation of test pieces . 4
6.1 Test pieces . 4
6.2 Test soil . 4
6.3 Method of depositing test soil on the test pieces . 4
7 Procedure. 4
7.1 Condition of the cleaning test. 4
7.2 Measurement of the test soil on test piece. 5
8 Calculation of the cleaning index of the soil . 5
9 Test report . 5
Annex A (informative) Method of depositing soil on the test pieces . 6
Annex B (informative) Operation of the test apparatus .10
Bibliography .12
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
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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 21256 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 2021 – All rights reserved

Introduction
Fine bubble technology has a number of applications across industries such as cleaning, transport,
maintenance, agriculture, aquaculture, food and drink, cosmetics as well as biomedical. This list is
expected to expand as fine bubble technology matures and becomes even more commonplace.
This document fills a gap in standards development in not only addressing a fine bubble cleaning
application but also providing an international hard flooring surfaces cleaning test method standard,
which also does not presently exist. Hard flooring surfaces cleaning and its standardization is important
to society as there is a public understanding that clean interior spaces, including flooring, also signifies
a safer and healthier environment, which provides peace of mind.
This document provides a detailed method, equipment specifics, an applicable soil formulation, analysis
of the results, and applicability.
United Nations Sustainable Development Goals – ISO Standards Contributions, Fine Bubble
Technology, Cleaning
Fine bubble technology (FBT) contributes positively toward the United Nations Sustainable
Development Goals (SDGs) to achieve a better and more sustainable future for all. Depending on the
application, FBT can directly support one or more of the SDGs, including Goal 6: Clean Water and
Sanitation, Goal 12: Responsible Production and Consumption, and Goal 13: Climate Action.
FBT solutions can be a substitute for chemical cleaning. The reduction in cleaning chemical use may be
directly measured and totalled in support of Goal 6: Clean Water and Sanitation. Eliminating the use of
cleaning chemicals reduces waste generation and also provides for the sound management of chemicals
and waste during their life cycle, which supports Goal 12: Responsible Consumption and Production.
Goal 13: Climate Action is supported through the reduced energy needs of FBT as compared to chemical
cleaners. The reduction in carbon dioxide emissions is primarily associated with the elimination of
recurring manufacturing and distribution of these chemical cleaners.
INTERNATIONAL STANDARD ISO 21256-3:2021(E)
Fine bubble technology — Cleaning applications —
Part 3:
Test method for cleaning hard flooring surfaces
1 Scope
This document specifies a test method for the cleaning of hard flooring surfaces. It can be used to
demonstrate the comparative cleaning performance of a fine bubble solution to an alternate cleaning
solution to remove contaminant from a soiled surface. This alternate cleaning solution can be another
fine bubble solution, municipal tap water or a commercially available cleaning solution blended to the
manufacturer’s specifications.
This method is not suitable for differentiating between cleaning solutions when the contaminant is
excessively applied on the surface as the mechanism of cleaning changes.
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
contaminant
foreign matter, undesired substances of organic and inorganic origin, undesired matter
3.2
test soil
hard flooring contaminant (3.1) standardized for testing purposes
3.3
test piece
hard flooring surface standardized for testing purposes
4 Principle
The principle is to evaluate the performance of contaminant removal by each cleaning solution by
measuring the mass of residual contaminate after exposure to the cleaning solutions.
5 Apparatus
5.1 Test equipment
The test equipment shall be as specified below.
Figure 1 shows a typical example of equipment for testing the fine bubble supply system, where the
difference in the result under the operation with the fine bubble generator on and off is to be compared.
a) The test apparatus uses a modified reciprocating scrub testing machine.
1) Replace the brush of the apparatus with a spray nozzle, which provides a light spray of the
cleaning solution as the nozzle repeatedly moves back and forth across the soil surface.
2) The nozzle type should be a hydraulic atomizing nozzle providing a hollow cone fine spray with
an approximate spray angle of 70° with a nominal diameter orifice of 1 mm.
b) Municipal tap water should be supplied with a flow rate of 0,45 ± 0,05 l/min.
NOTE This flow rate is typical for walk-behind hard floor cleaning equipment.
c) The diameter of the hollow cone spray at the contaminant surface should be 70 mm to 80 mm.
d) The nozzle tip should be approximately 45 mm above the test piece, creating a spay cone wider
than the soil pattern on the substrate.
e) The centre of the soil pattern of the test piece shall be placed under the path of the nozzle travel
...