prEN ISO 14644-13

SLOVENSKI STANDARD
01-december-2025
Čiste sobe in podobna nadzorovana okolja - 13. del: Čiščenje površin za
doseganje določenih ravni čistoče po klasifikaciji delcev in kemikalij (ISO/FDIS
14644-13:2025)
Cleanrooms and associated controlled environments - Part 13: Cleaning of surfaces to
achieve defined levels of cleanliness in terms of particle and chemical concentration
(ISO/FDIS 14644-13:2025)
Reinräume und zugehörige Reinraumbereiche - Teil 13: Reinigung von Oberflächen zur
Erreichung definierter Reinheitsgrade hinsichtlich Partikel- und
Chemikalienklassifikationen (ISO/FDIS 14644-13:2025)
Salles propres et environnements maîtrisés apparentés - Partie 13: Nettoyage des
surfaces afin d'obtenir des niveaux de propreté par rapport aux classifications
particulaire et chimique (ISO/FDIS 14644-13:2025)
Ta slovenski standard je istoveten z: prEN ISO 14644-13
ICS:
13.040.35 Brezprašni prostori in Cleanrooms and associated
povezana nadzorovana controlled environments
okolja
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

FINAL DRAFT
International
Standard
ISO/FDIS 14644-13
ISO/TC 209
Cleanrooms and associated
Secretariat: ANSI
controlled environments —
Voting begins on:
Part 13:
Cleaning of surfaces to achieve
Voting terminates on:
defined levels of cleanliness in
terms of particle and chemical
concentration
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WITH THEIR COMMENTS, NOTIFICATION OF ANY
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TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
ISO/FDIS 14644-13:2025(en) © ISO 2025

FINAL DRAFT
ISO/FDIS 14644-13:2025(en)
International
Standard
ISO/FDIS 14644-13
ISO/TC 209
Cleanrooms and associated
Secretariat: ANSI
controlled environments —
Voting begins on:
Part 13:
Cleaning of surfaces to achieve
Voting terminates on:
defined levels of cleanliness in
terms of particle and chemical
concentration
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.
© ISO 2025
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/CEN PARALLEL PROCESSING
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
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Published in Switzerland Reference number
ISO/FDIS 14644-13:2025(en) © ISO 2025

ii
ISO/FDIS 14644-13:2025(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 2
3 Terms and definitions . 2
4 General methodology . 3
4.1 Overview .3
4.2 Methodology .4
5 Object description . 5
6 Cleanliness specifications . 6
7 Determination of initial contamination level . 6
7.1 General .6
7.2 Determination of initial contamination level with respect to particle concentration .6
7.3 Determination of initial contamination level with respect to chemical concentration .6
8 Other requirements . . 7
9 Selection of a cleaning methodology . 7
9.1 Selection procedure .7
9.2 Cleaning methodologies .7
9.2.1 Cleaning method .7
9.2.2 Categories of cleaning techniques .7
9.3 Cleaning process .8
10 Material compatibility check . 8
11 Cleaning validation . 8
11.1 General .8
11.2 Cleaning efficiency .9
11.2.1 Evaluation .9
11.2.2 Cleaning efficiency with respect to particle concentration .10
11.2.3 Cleaning efficiency with respect to chemical contamination .11
11.3 Cleaning appropriateness .11
11.3.1 Assessment .11
11.3.2 Cleaning appropriateness with respect to particle concentration . 12
11.3.3 Cleaning appropriateness with respect to chemical concentration . 13
12 Measurement methods . 14
12.1 General .14
12.2 Direct measurement methods .14
12.2.1 General .14
12.2.2 Direct measurement methods with respect to SCP .14
12.2.3 Direct measurement methods with respect to SCC .14
12.3 Indirect measurement methods .14
12.3.1 General .14
12.3.2 Indirect measurement methods with respect to SCP . . 15
12.3.3 Indirect measurement methods with respect to SCC . 15
13 Documentation .15
Annex A (informative) Aspects of cleaning . 17
Annex B (informative) Cleaning methods .18
Annex C (informative) Material compatibility with cleaning agents .25
Annex D (informative) Cleanliness measurement .27

iii
ISO/FDIS 14644-13:2025(en)
Bibliography .32

iv
ISO/FDIS 14644-13:2025(en)
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 209, Cleanrooms and associated controlled
environments, in collaboration with the European Committee for Standardization (CEN) Technical Committee
CEN/TC 243, Cleanroom technology, in accordance with the Agreement on technical cooperation between
ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 14644-13:2017), of which it constitutes a
minor revision. The changes are as follows:
— term class (classification, classified) changed to levels or assessment where appropriate;
— updated document titles and issue dates where appropriate;
— minor editorial changes;
— removed references not cited in the document.
A list of all parts in the ISO 14644 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.

v
ISO/FDIS 14644-13:2025(en)
Introduction
The term surface refers to the interface between two phases. For the purpose of this document, the surface
is a solid. A “clean surface” is where one or more of the contamination categories (particles, chemical) are
under control due to cleaning/decontamination. The degree of cleanliness is specified in the corresponding
surface cleanliness levels (see ISO 14644-9 and ISO 14644-10). Different cleaning methods are necessary
depending on the degree of cleanliness (cleanliness level) required. This document gives guidance on the
selection of cleaning methods to achieve specified cleanliness levels. For the selection procedure, the aspects
of surface description, cleanliness specifications, types of contamination, cleaning techniques, material
compatibility, and assessment methodology are taken into consideration. Most of the methods are suitable
for removal of more than one contamination category at the same time; therefore, a common standard for
the selection of a cleaning method for both particles, as well as chemical contamination, is needed.

vi
FINAL DRAFT International Standard ISO/FDIS 14644-13:2025(en)
Cleanrooms and associated controlled environments —
Part 13:
Cleaning of surfaces to achieve defined levels of cleanliness in
terms of particle and chemical concentration
1 Scope
This document gives guidelines for cleaning to a specified degree on cleanroom surfaces, surfaces of
equipment in a cleanroom and surfaces of materials in a cleanroom. Under consideration are all surfaces
(external or internal) that are of interest. It provides guidance on the assessment of cleaning methods for
achieving the required surface cleanliness by particle concentration (SCP) and surface cleanliness by chemical
concentration (SCC) levels and which techniques should be considered to achieve these specified levels.
The appropriateness of cleaning techniques will make reference to the cleanliness levels and associated test
methods found in ISO 14644-9 and ISO 14644-10.
The document gives general guidance on the following:
— expected surface cleanliness levels;
— suitability of cleaning methods;
— compatibility of surfaces with the cleaning technique;
— assessment of cleaning appropriateness.
The following are excluded from this document:
— classification of cleaning methods;
— product produced within a cleanroom;
— specific surface-related cleaning methods;
— detailed description of cleaning mechanisms, methods and procedures of various cleaning methods;
— detailed material characteristics;
— description of damage mechanisms by cleaning processes and time-dependent effects;
— references to interactive bonding forces between contaminants and surfaces or generation processes
that are usually time-dependent and process-dependent;
— other characteristics of particles such as electrostatic charge, ionic charges, etc.;
— chemical reactions between molecular contaminants and surfaces;
— microbiological aspects of surface cleanliness;
— radioactive aspects of contamination;
— health and safety considerations;
— environmental aspects such as waste disposal, emissions, etc.;

ISO/FDIS 14644-13:2025(en)
— selection and use of statistical methods.
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 14644-8, Cleanrooms and associated controlled environments — Part 8: Assessment of air cleanliness by
chemical concentration (ACC)
ISO 14644-9, Cleanrooms and associated controlled environments — Part 9: Assessment of surface cleanliness
for particle concentration
ISO 14644-10, Cleanrooms and associated controlled environments — Part 10: Assessment of surface cleanliness
for chemical contamination
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 14644-9, ISO 14644-10 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
cleanliness
condition of a solid surface where the amount of contamination (3.4) (particle, chemical)
is controlled to a specific level
3.2
cleaning appropriateness
relation between the required cleanliness (3.1) and the accomplished cleanliness under controlled conditions
Note 1 to entry: In some languages, the term cleaning efficacy is used to indicate cleaning appropriateness.
Note 2 to entry: In case of real operational conditions or monitoring, the term cleaning effectiveness is used.
3.3
cleaning efficiency
fraction of specific contaminants removed from a surface by a cleaning process
Note 1 to entry: The fraction is determined by the accomplished surface cleanliness in respect to the initial surface
cleanliness.
3.4
contamination
unwanted matter in an undesirable location
3.5
particle
minute piece of matter with defined physical boundaries
[SOURCE: ISO 14644-1:2015, 3.2.1]
3.6
particle contamination
particles (3.5) having the potential to affect the process, the product, the personnel or the facilities

ISO/FDIS 14644-13:2025(en)
3.7
particle size
diameter of a sphere that produces a response, by a given particle-sizing instrument, that is equivalent to
the response produced by the particle (3.5) being measured
4 General methodology
4.1 Overview
Multiple aspects need to be considered for cleaning. Figure 1 provides an overview of the factors that
contribute to the suitability of cleaning methods to achieve a defined level of surface cleanliness. For more
details, see Annex A.
Key
more details in Figure A.1
Figure 1 — Overview of cleaning aspects (non-exhaustive)

ISO/FDIS 14644-13:2025(en)
4.2 Methodology
Appropriateness of a cleaning technique for an application depends on many factors. For complex objects, it
is advised to follow the sequence described in this clause and in the decision tree (see Figure 2). By using this
procedure, it can be assured that all important issues are covered. For simple objects or surfaces, deviations
from the sequence are allowable, as long as the critical information is documented.
The approach starts with describing the object that has to be cleaned. The description should cover, among
others, composition of materials, chemical characteristics, surface finish and shape factors like geometrical
complexity and size (step 1). In the second step, the objective of the cleaning procedure is to be specified in
terms of the desired cleanliness of the object. To have a starting point, the initial contamination level should
be assessed (step 3) and other requirements shall be listed (step 4). Based on type of contaminants and
the required removal efficiency, a cleaning technique or a combination of techniques can be selected (step
5). The cleaning methodology shall be checked against the materials from the first step in order to avoid
material compatibility issues (step 6). At the last step, a validation method shall be carried out (step 7).
The validation shall at least comprise methods for determination of the cleaning performance and material
compatibility. The performance of the cleaning shall be checked against the specification.
Figure 2 — Decision tree
ISO/FDIS 14644-13:2025(en)
5 Object description
In the object description, the following aspects shall be considered.
a) Physical properties of the object:
— physical dimensions;
— form/shape/complexity of the object;
— critical surfaces.
A general description of the object shall be given. Size, shape, complexity and identification of the critical
surfaces set many boundary conditions for a cleaning method.
b) Surface(s):
— material composition of the object surface(s);
— complexity;
— materials/critical materials (sensitive to cleaning agents);
— thin/atomic surface layers (e.g. protective layers);
— other physical properties (e.g. electrostatic).
The composition of the object can be simple (one or more similar material(s)) or a system consisting of
a range of different materials (e.g. metal/plastic/glass composition). Each individual material should
be taken into account when choosing a cleaning method. Some combinations of materials can be very
difficult to clean as one cleaning method may be suitable for one material but not the other. The selection
of the cleaning method shall be the best compromise between minimal damage of the materials at
maximum cleaning efficiency.
c) Chemical properties of the surface(s):
— chemical composition;
— state of the surface (hydrophobic, hydrophilic, lipophobic, lipophilic, etc.);
— energetic state of the surface (zeta potential).
Physical and chemical properties of a surface have a large influence on the choice of a cleaning method.
Choice of a method shall take into account all involved materials/chemical composition of the surface(s)
and the combination of materials undergoing cleaning.
The activity of the surface is determined by the chemical configuration of the final atomic layer. This is
an important parameter in determining the choice of method. These layers may be hydrophilic (water
wettable-lipophobic) or hydrophobic (water repellent but oil-wettable-lipophilic). The cleaning method
used can influence the surface activity. The surface activity also influences the electrostatic properties
of a material — a hydrophilic surface will have fewer tendencies to electrically charge.
d) Morphology:
Cleaning is influenced by the morphological aspects of a surface such as shape, size, structure, surface
roughness or porosity. Morphological aspects may further complicate cleaning due to the accessibility
of the surfaces to be cleaned and to the retention of cleaning agents and materials used for cleaning.
e) Object specific requirements:
— intended use of the object;
— environmental conditions, both pre- and post-cleaning;

ISO/FDIS 14644-13:2025(en)
— critical surfaces, surfaces with either high importance in the application or sensitive to cleaning.
6 Cleanliness specifications
The rationale of determining appropriateness of the cleaning method should include the contaminants of
concern, as well as acceptable levels of contamination for the application.
The required cleanliness shall be specified in terms of particle concentration according to ISO 14644-9 and/
or in terms of the concentration of a specific group of chemicals according to ISO 14644-10.
The specification of the targeted cleanliness level can be determined in various ways:
— cleanliness level required by customer;
— common cleanliness level required for similar objects;
— by performing an analysis on the impact of contamination of the surface in the (future) function of a
product or process where the cleaned surface will be used;
— by performing tests or simulations with various cleanliness levels of the considered surface and/or;
— by performing an analysis of the contamination that caused failure or quality loss.
7 Determination of initial contamination level
7.1 General
To select the cleaning procedure for achieving a required surface cleanliness level, the initial surface
cleanliness shall be established. The initial surface cleanliness by chemical and/or particle concentration
shall be determined for the surfaces of interest. This can be determined qualitatively or quantitatively.
Qualitative evaluation is a non-numerical assessment (e.g. a visual inspection).
Where the quantitative surface cleanliness is determined, it can be related to the efficiency of the cleaning
procedure in respect to the required surface cleanliness by particle concentration and/or chemical
concentration. The quantified contamination (particle and/or chemical) shall be related to the area of the
representative surface. This evaluation allows determination of the initial cleanliness level.
7.2 Determination of initial contamination level with respect to particle concentration
The initial surface cleanliness by particle concentration shall be determined for the different surfaces.
Depending on the required cleanliness level, a qualitative assessment of the initial cleanliness level may
be sufficient. For quantitative assessment, the number and size of particles shall be characterized by
a measurement method as described in Clause 12. The surface cleanliness grading level as outlined in
ISO 14644-9 shall be applied.
The quantified particle concentration shall be related to the area of the representative surface. This
evaluation allows determination of the initial cleanliness level.
7.3 Determination of initial contamination level with respect to chemical concentration
The initial surface cleanliness by chemical concentration shall be determined for the different surfaces.
Depending on the specific application, a qualitative assessment (e.g. water break test) of the initial cleanliness
level might be sufficient. For quantitative assessment of the mass and nature of the chemical contaminants,
a measurement technique according to Clause 12 and ISO 14644-10 shall be applicable.
The quantified chemical contamination shall be related to the area of the representative surface. This
evaluation allows determination of the initial cleanliness level.

ISO/FDIS 14644-13:2025(en)
8 Other requirements
In addition to requirements for cleaning appropriateness and product integrity, many other elements
influence the applicability of the cleaning method. In step 5 of the decision tree (see Figure 2), these other
aspects shall be listed and requirements shall be defined. The contents of these requirements are strongly
related to the object or surface and its application.
Typical examples for other requirements are time available for cleaning, number of items that will be
cleaned, available footprint, waste, investment and labour costs, level of operator skill and environmental
aspects.
9 Selection of a cleaning methodology
9.1 Selection procedure
Requirements for cleaning are defined in Clause 5 to Clause 8. These requirements shall be considered
during the selection process for the cleaning methodology to ensure the greatest uniformity between the
requirements and the method.
The final decision of the choice of cleaning methodology shall be based on a combination of all aspects to find
the technically and financially optimal, most efficient solution. The customer, the clean technology supplier
and the process owner of the surface/object/component to be cleaned should be involved in this selection
process. The decision optimizes the various parameters and shall assure specified surface quality. Table B.1
and Table B.2 can aid the selection process.
9.2 Cleaning methodologies
9.2.1 Cleaning method
A cleaning methodology consists of a cleaning technique (e.g. wiping, plasma cleaning and ultrasonic
cleaning) and a cleaning process. The cleaning process is linked to the cleaning techniques and involves
the amount of mechanical energy, chemical energy, temperature and process time. By using a balanced
combination of these four process parameters, the optimum cleaning result can be achieved. Final cleanliness
can be limited by substrate damage and/or selection criteria defined in Clause 8.
The required cleanliness level and the initial cleanliness level in particle and/or chemical concentration led
to a selection of cleaning methods. In case the initial cleanliness level is high and the required cleanliness
level is low, a combination of methods may be required.
9.2.2 Categories of cleaning techniques
The cleaning techniques can be divided depending on the major cleaning mechanism into physical and
chemical cleaning which additionally can be divided into wet and dry-cleaning techniques. Whether a
process is categorized as physical/chemical or as wet/dry depends on the dominant mechanism used for the
cleaning. A non-exhaustive list of physical cleaning techniques can be found in B.2 (mechanical cleaning),
B.3 (fluidic cleaning), and B.4 (blasting cleaning techniques). A list of chemical cleaning techniques can be
found in B.5 (chemical cleaning). References to the categories of cleaning techniques are given in Table 1.
Table 1 — Categorization of cleaning techniques as described in Annex B
Cleaning technique Physical Chemical
Dry B.2, B.4 dry B.5 dry
Wet B.3, B.4 wet B.5 wet
The numbers refer to subclauses within Annex B that provide a brief description of the major cleaning
techniques.
ISO/FDIS 14644-13:2025(en)
Table B.1 and Table B.2 support the choice of an appropriate cleaning technique (physical/chemical)
that fulfils the cleanliness specifications. With the help of feasibility tests on material compatibility (see
Clause 10) and empirical values/evaluation, the best suitable technique shall be chosen for validation (see
Clause 11).
9.3 Cleaning process
In Table B.1 and Table B.2, an overview is given on the working ranges for different cleaning techniques. In
these ranges, optimum process conditions are assumed. Since material properties and other requirements
can require the use of suboptimum conditions, the actual cleaning efficiency and appropriateness can be
lower. The process settings shall be defined either by an experimental investigation or from experience.
10 Material compatibility check
The compatibility of materials with cleaning agents shall be considered. These cleaning agents (e.g.
chemicals, solvents, high pressure gas or liquid) shall be selected with respect to their compatibility with the
materials or items to be cleaned and their efficiency in removing different kinds of contaminants: particle or
chemical contaminants.
Detrimental effects on surfaces can be caused by the cleaning agents and/or the cleaning technique.
The chemical nature of the materials of the surface — individually or in combination depending on the
composition of the surface — should be evaluated technically.
The following describes such direct, indirect and long duration effects.
— Direct effects are changes of intrinsic material properties (physical and/or chemical) as a consequence
of the interaction with a process parameter from the cleaning technique: chemical nature of a solvent,
time of exposure and temperature.
EXAMPLE 1 The change of the chemical surface structure may strongly change the physical behaviour. Change
of the hydrophilic character of the last atomic layer to hydrophobic through the cleaning process may change the
physical behaviour of the cleaned surface, i.e. wettability and electrostatic charge. Hydrophobic surface is not
wettable and is easily charged which may attract particles.
EXAMPLE 2 Change in surface roughness.
— Indirect effects can be caused by different physical-chemical mechanisms as a consequence of secondary
interactions (e.g. chemical reactions with specific compounds of the substrate) or as an interaction
with a non-process parameter (post-degradation or oxidation by O of air, deposits of residues as a new
contamination).
NOTE An indirect effect might not be observed immediately.
— Long duration effects result from a slow process (e.g. induced corrosion from chemical conversion after
chemical cleaning, ageing and weakening).
Annex C gives an overview of compatibility with chemical solvents; it is a non-exhaustive list. In the case of
a lack of information for a specific cleaning solvent, the chemical resistance of the material shall be assessed
through an appropriate test.
11 Cleaning validation
11.1 General
To assess the suitability of a selected cleaning procedure, the cleaning efficiency and the cleaning
appropriateness should be considered.
For the validation of a cleaning process to reach the required surface cleanliness with respect to particle
concentration and/or chemical concentration, the achieved surface cleanliness SCP and/or SCC levels should
be determined.
ISO/FDIS 14644-13:2025(en)
Other performance-related aspects, such as repeatability, reproducibility and operator influences, shall also
be considered. In Clause 8, a set of requirements are defined that are not related to cleaning performance.
Although these requirements are taken into account during the selection of the cleaning method, the
validation process shall verify that these requirements are fulfilled.
Figure 3 and Figure 4 are depictions of the terms cleaning efficiency and cleaning appropriateness.
Cleaning efficiency = 1 − final cleanliness level/initial cleanliness level (expressed as a percentage)
Cleaning appropriateness = required cleanliness level/final cleanliness level
Figure 3 — Example for a method with low cleaning efficiency leading to unsuitable cleaning
appropriateness
Figure 4 — Example for a method with high cleaning efficiency leading to suitable cleaning
appropriateness
11.2 Cleaning efficiency
11.2.1 Evaluation
For evaluation of the cleaning efficiency, the initial surface cleanliness level and final cleanliness level shall
be determined.
ISO/FDIS 14644-13:2025(en)
11.2.2 Cleaning efficiency with respect to particle concentration
The cleaning efficiency is calculated by Formula (1):
fin
C
SCP;D
C =−1 (1)
eff
ini
C
SCP;D
where
D is the particle size, in micrometres (µm);
ini
C is the initial surface concentration, in particles per square metre of surface, of particles that are
SCP;D
equal to or larger than the considered particle size D in µm;
fin
C is the final surface concentration, in particles per square metre of surface, of particles that are
SCP;D
equal to or larger than the considered particle size D in µm.
In accordance with ISO 14644-9, the relation with the surface cleanliness level is given by Formula (2):
SCP;N
Ck= (2)
SCP;D
D
where
C is the maximum permitted total surface concentration, in particles per square metre of surface,
SCP;D
of particles that are equal to or larger than the considered particle size;
SCP;N is the SCP level number;
D is the considered particle size, in micrometres;
k is the constant 1, in micrometres.
Combining Formula (1) and Formula (2) gives the cleaning efficiency in terms of SCP, in Formula (3):
SCP;N
fin
k
SCP;N
fin
SCP;NN− SCP;
()
D finini
C =−1 = 1− = 11− 0 (3)
eff
SCP;N SCP;N
ini ini
10 10
k
D
where
D is the particle size, in micrometres;
SCP;N is the SCP level number;
SCP;N is the SCP level number of the final surface cleanliness of particles;
fin
SCP;N is the SCP level number of the initial surface cleanliness of particles.
ini
NOTE The cleaning efficiency can also be expressed as a percentage (%).
EXAMPLE In this example, the smallest particle size that can be measured with the applied measurement method
is 5 µm. Therefore, the concentration of the number of particles ≥5 µm is used.
ini
The initial concentration of particles ≥5 µm per m C is 600 000. Therefore, the SCP;N = lg (600 000 × 5) = 6,5.
ini
SCP;5
The initial surface cleanliness level SCP;N = 6,5 for particles equal to or larger than 5 µm.
ini
fin
After cleaning, the final concentration of particles ≥5 µm per m C is 1 000. Therefore, the
SCP;5
SCP;N = lg (1 000 × 5) = 3,7.
fin
The final surface cleanliness level SCP;N = 3,7 for particles equal to or larger than 5 µm.
fin
The cleaning efficiency in terms of particle concentration = 1 − (1 000)/(600 000) = 1 − 1/600 = 0,998 or 99,8 % for
particles ≥5 µm.
ISO/FDIS 14644-13:2025(en)
(3,7 − 6,5) -2,8
Similarly, the cleaning efficiency in respect to the SCP levels = 1 − 10 = 1 – 10 = 0,998 4 or 99,8 % for
particles ≥5 µm.
11.2.3 Cleaning efficiency with respect to chemical contamination
The cleaning efficiency is calculated by Formula (4):
fin
C
SCC
C =−1 (4)
eff
ini
C
SCC
where
ini
C is the initial concentration of the considered chemical (g/m );
SCC
fin
C is the final concentration of the considered chemical (g/m ).
SCC
According to ISO 14644-10, the relation with the surface cleanliness level by chemical concentration (SCC) is
given by Formula (5):
SCC;N
C = 10 (5)
SCC
where SCC;N is the surface cleanliness of chemical concentration by level.
Combining Formula (4) and Formula (5) gives the cleaning efficiency in terms of SCC, in Formula (6):
SCC;N
fin
10 ()SCC;NN−SCC;
finini
C =−1 = 11− 0 (6)
eff
SCC;N
ini
NOTE The cleaning efficiency can also be expressed as a percentage (%).
EXAMPLE The initial concentration of the hydrocarbons is 50 mg per m for hydrocarbons.
Therefore, the
−3
SCC;N =×lg 50 10 =−13,
( )
ini
for hydrocarbons.
The final concentration of the hydrocarbons is 10 µg per m .
Therefore, the
−6
SCC;N =×��lg 10 10 =−� 50, .
)
fin (
The cleaning efficiency in terms of chemical concentration =
−6 −6
1 − 10 × 10 /50 × 1 000 × 10 = 1 − 10/50 000 = 0,999 8 or 99,98 % for hydrocarbons.
(−5,0 + 1,3) −3,7
Similarly, the cleaning efficiency in respect to the SCC levels = 1 − 10 = 1 − 10 = 0,999 8 or 99,98 % for
hydrocarbons.
11.3 Cleaning appropriateness
11.3.1 Assessment
For evaluation of the cleaning appropriateness, the final cleanliness level obtained shall be determined and
compared to the required surface cleanliness.

ISO/FDIS 14644-13:2025(en)
11.3.2 Cleaning appropriateness with respect to particle concentration
The cleaning appropriateness is calculated by Formula (7):
requ
C
SCP;D
C = (7)
app
fin
C
SCP;D
where
requ
C is the required concentration of particles equal to or larger than D µm;
SCP;D
fin
C is the final particle concentration obtained of particles equal to or larger than D µm.
SCP;D
D is the particle size, in micrometres.
According to ISO 14644-9, the relation with the surface cleanliness level is given by Formula (8):
SCP;N
Ck= (8)
SCP;D
D
where
C is the concentration of particles equal to or larger than D µm;
SCP;D
D is the particle size, in micrometres;
SCP;N is the SCP level number.
Combining Formula (7) and Formula (8) gives the cleaning appropriateness in terms of SCP level, in
Formula (9):
SCP;N
requ
SCP;NN− SCP;
()
requ fin
C = = 10 (9)
app
SCP;N
fin
If the cleaning appropriateness is less than 1, the chosen cleaning procedure was not suitable.
If the cleaning appropriateness is equal or greater than 1, the chosen cleaning procedure was suitable and
results in a surface at the required cleanliness level.
NOTE The cleaning appropriateness can also be expressed as a percentage (%).
EXAMPLE In this example, the smallest particle size that can be measured with the applied
...