EN ISO 14644-4:2001

SLOVENSKI STANDARD
01-januar-2002
Cleanrooms and associated controlled environments - Part 4: Design,
construction and start-up (ISO 14644-4:2001)
Cleanrooms and associated controlled environments - Part 4: Design, construction and
start-up (ISO 14644-4:2001)
Reinräume und zugehörige Reinraumbereiche - Teil 4: Planung, Ausführung und Erst-
Inbetriebnahme (ISO 14644-4:2001)
Salles propres et environnements maîtrisés apparentés - Partie 4: Conception,
construction et mise en fonctionnement (ISO 14644-4:2001)
Ta slovenski standard je istoveten z: EN ISO 14644-4:2001
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.

EUROPEAN STANDARD
EN ISO 14644-4
NORME EUROPÉENNE
EUROPÄISCHE NORM
April 2001
ICS 13.040.30
English version
Cleanrooms and associated controlled environments - Part 4:
Design, construction and start-up (ISO 14644-4:2001)
Salles propres et environnements maîtrisés apparentés - Reinräume und zugehörige Reinraumbereiche - Teil 4:
Partie 4: Conception, construction et mise en Planung, Ausführung und Erst-Inbetriebnahme (ISO 14644-
fonctionnement (ISO 14644-4:2001) 4:2001)
This European Standard was approved by CEN on 1 April 2001.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Management Centre or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Management Centre has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece,
Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2001 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 14644-4:2001 E
worldwide for CEN national Members.

Page 2
CORRECTED  2003-03-26
Foreword
The text of the International Standard ISO 14644-4:2001 has been prepared by Technical
Committee ISO/TC 209 "Cleanrooms and associated controlled environments" in
collaboration with Technical Committee CEN/TC 243 "Cleanroom technology", the secretariat
of which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication
of an identical text or by endorsement, at the latest by October 2001, and conflicting national
standards shall be withdrawn at the latest by October 2001.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy,
Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United
Kingdom.
Endorsement notice
The text of the International Standard ISO 14644-4:2001 was approved by CEN as a
European Standard without any modification.
NOTE: Normative references to International Standards are listed in annex ZA (normative).

Page 3
Annex ZA
(normative)
Normative references to international publications with their corresponding
European publications
This European Standard incorporates, by dated or undated reference, provisions from other
publications. These normativereferences are cited at the appropriate places in the text, and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions
of any of these publications apply to this European Standard only when incorporated in it by
amendment or revision. For undated references the latest edition of the publication referred to
applies (including amendments).
NOTE Where an International Publication has been modified bycommon modifications, indicated by
(mod.), the relevant EN/HD applies.
Publication Year Title EN/HD Year
ISO 14644-1 1999 Cleanrooms and associated controlled EN ISO 14644-1 1999
environments — Part 1: Classification of air
cleanliness
ISO 14644-2 2000 Cleanrooms and associated controlled EN ISO 14644-2 2000
environments — Part 2: Specifications for
testing and monitoring to prove continued
compliance with ISO 14644-1
INTERNATIONAL ISO
STANDARD 14644-4
First edition
2001-04-01
Cleanrooms and associated controlled
environments —
Part 4:
Design, construction and start-up
Salles propres et environnements maîtrisés apparentés —
Partie 4: Conception, construction et mise en fonctionnement
Reference number
ISO 14644-4:2001(E)
©
ISO 2001
ISO 14644-4:2001(E)
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ii © ISO 2001 – All rights reserved

ISO 14644-4:2001(E)
Contents
Foreword.iv
Introduction.v
1 Scope .1
2 Normative references .1
3 Terms and definitions .2
4 Requirements.3
5 Planning and design.4
5.1 Planning procedure .4
5.2 Design .5
6 Construction and start-up.5
7 Testing and approval.6
7.1 General.6
7.2 Construction approval .6
7.3 Functional approval.6
7.4 Operational approval.6
8 Documentation.6
8.1 General.6
8.2 Record of an installation.6
8.3 Operational instructions .6
8.4 Instructions for performance monitoring.7
8.5 Maintenance instructions .7
8.6 Maintenance record.7
8.7 Record of operation and maintenance training.8
Annex A (informative) Control and segregation concepts.9
Annex B (informative) Classification examples .16
Annex C (informative) Approval of an installation.19
Annex D (informative) Layout of an installation.23
Annex E (informative) Construction and materials.27
Annex F (informative) Environmental control of cleanrooms .32
Annex G (informative) Control of air cleanliness.35
Annex H (informative) Additional specification of requirements to be agreed upon between
purchaser/user and designer/supplier .37
Bibliography.50
ISO 14644-4:2001(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 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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this part of ISO 14644 may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
International Standard ISO 14644-4 was prepared by Technical Committee ISO/TC 209, Cleanrooms and
associated controlled environments.
ISO 14644 consists of the following parts, under the general title Cleanrooms and associated controlled
environments:
� Part 1: Classification of air cleanliness
� Part 2: Specifications for testing and monitoring to prove continued compliance with ISO 14644-1
� Part 3: Metrology and test methods
� Part 4: Design, construction and start-up
� Part 5: Operations
� Part 6: Vocabulary
� Part 7: Separative enclosures (clean air hoods, glove boxes, isolators, mini-environments)
Users should note that the titles listed for parts 3 and 5 to 7 are working titles at the time of the release of part 4. In
the event that one or more of these parts are deleted from the work programme, the remaining parts may be
renumbered.
Annexes A to H of this part of ISO 14644 are for information only.
iv © ISO 2001 – All rights reserved

ISO 14644-4:2001(E)
Introduction
Cleanrooms and associated controlled environments provide for the control of airborne particulate contamination to
levels appropriate for accomplishing contamination-sensitive activities. Products and processes that benefit from
the control of airborne contamination include those in such industries as aerospace, microelectronics,
pharmaceuticals, medical devices and healthcare.
This part of ISO 14644 specifies the requirements for the design and construction of cleanroom facilities. It is
intended for use by purchasers, suppliers and designers of cleanroom installations and provides a check list of
important parameters of performance. Construction guidance is provided, including requirements for start-up and
qualification. Basic elements of design and construction needed to ensure continued satisfactory operation are
identified through the consideration of relevant aspects of operation and maintenance.
This part of ISO 14644 is one of a series of standards concerned with cleanrooms and associated subjects. Many
factors besides design, construction and start-up should be considered in the operation and control of cleanrooms
and other controlled environments. These are covered in some detail in other International Standards prepared by
ISO/TC 209.
INTERNATIONAL STANDARD ISO 14644-4:2001(E)
Cleanrooms and associated controlled environments
Part 4:
Design, construction and start-up
1 Scope
This part of ISO 14644 specifies requirements for the design and construction of cleanroom installations but does
not prescribe specific technological or contractual means to meet these requirements. It is intended for use by
purchasers, suppliers and designers of cleanroom installations and provides a checklist of important parameters of
performance. Construction guidance is provided, including requirements for start-up and qualification. Basic
elements of design and construction needed to ensure continued satisfactory operation are identified through the
consideration of relevant aspects of operation and maintenance.
NOTE Further guidance in respect of the above requirements is given in annexes A to H. Other parts of ISO 14644 may
provide complementary information.
Application of this part of ISO 14644 is restricted in the following:
� user requirements are represented by purchaser or specifier;
� specific processes to be accommodated in the cleanroom installation are not specified;
� fire and safety regulations are not considered specifically; the appropriate national and local requirements
should be respected;
� process media and utility services are only considered with respect to their routing between and in the different
zones of cleanliness;
� regarding initial operation and maintenance, only cleanroom construction-specific requirements are
considered.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of
this part of ISO 14644. For dated references, subsequent amendments to, or revisions of, any of these publications
do not apply. However, parties to agreements based on this part of ISO 14644 are encouraged to investigate the
possibility of applying the most recent editions of the normative documents indicated below. For undated
references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain
registers of currently valid International Standards.
ISO 14644-1:1999, Cleanrooms and associated controlled environments — Part 1: Classification of air cleanliness.
ISO 14644-2:2000, Cleanrooms and associated controlled environments — Part 2: Specifications for testing and
monitoring to prove continued compliance with ISO 14644-1.
ISO 14644-4:2001(E)
1�
ISO 14644-3:— , Cleanrooms and associated controlled environments — Part 3: Metrology and test methods.
1)
ISO 14698-1:— , Cleanrooms and associated controlled environments — Biocontamination control —
Part 1: General principles
1)
ISO 14698-2:— , Cleanrooms and associated controlled environments — Biocontamination control —
Part 2: Evaluation and interpretation of biocontamination data.
1)
ISO 14698-3:— , Cleanrooms and associated controlled environements — Biocontamination control —
Part 3: Measurement of the efficiency of processes of cleaning and/or disinfection of inert surfaces bearing
biocontaminated wet soiling or biofilms.
3 Terms and definitions
For the purposes of this part of ISO 14644, the terms and definitions given in ISO 14644-1 and the following apply.
3.1
changing room
room where people using a cleanroom may change into, or out of, cleanroom apparel
3.2
clean air device
stand-alone equipment for treating and distributing clean air to achieve defined environmental conditions
3.3
cleanliness
condition of a product, surface, device, gas, fluid, etc. with a defined level of contamination
NOTE Contamination can be particulate, non-particulate, biological, molecular or of other consistency.
3.4
commissioning
planned and documented series of inspections, adjustments and tests carried out systematically to set the
installation into correct technical operation as specified
3.5
contaminant
any particulate, molecular, non-particulate and biological entity that can adversely affect the product or process
3.6
non-unidirectional airflow
air distribution where the supply air entering the clean zone mixes with the internal air by means of induction
3.7
particle
minute piece of matter with defined physical boundaries
NOTE For classification purposes refer to ISO 14644-1.
3.8
pre-filter
air filter fitted upstream of another filter to reduce the challenge on that filter
1�
To be published.
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ISO 14644-4:2001(E)
3.9
process core
location at which the process and the interaction between the environment and the process occurs
3.10
start-up
act of preparing and bringing an installation into active service, including all systems
EXAMPLE Systems may include procedures, training requirements, infrastructure, support services, statutory under-
takings requirements.
3.11
unidirectional airflow
controlled airflow through the entire cross-section of a clean zone with a steady velocity and approximately parallel
streamlines
NOTE This type of airflow results in a directed transport of particles from the clean zone.
4 Requirements
4.1 The parameters listed in 4.2 to 4.18 shall be defined and agreed between purchaser and supplier:
NOTE In the requirements stated below, references are made to annexes A to H which are for information only.
4.2 The number, edition and date of publication of this part of ISO 14644 shall be given.
4.3 The role of other relevant parties to the project (e.g. consultants, designers, regulatory authorities, service
organizations) shall be established (see examples in annex C).
4.4 The general purpose for which the cleanroom is to be used, the operations to be carried out therein and any
constraint imposed by the operating requirements (see examples in annexes A, B and D).
4.5 The required airborne particulate cleanliness class or demands for cleanliness in accordance with the
relevant International Standard (ISO 14644-1, ISO 14698-1, ISO 14698-2 and ISO 14698-3) (see examples in
annex B).
4.6 The critical environmental parameters, including their specified set points, alert and action levels to be
measured to ensure compliance, together with the measurement methods to be used, including calibration
(ISO 14644-2 and ISO 14644-3) (see examples in annex F).
4.7 The contamination control concept, including installation, operating and performance criteria, to be used to
achieve the required cleanliness level (see examples in annex A).
4.8 The methods of measurement, control, monitoring and documentation required to meet the parameters
agreed (see examples in annexes C and F).
4.9 The entry or exit of equipment, apparatus, supplies and personnel required to support the installation (see
examples in annex D).
4.10 The specified occupancy states selected from "as-built", "at-rest" and "operational" under which the required
parameters shall be achieved and maintained including variations with time, and the methods of control (see
examples in annex C).
4.11 The layout and configuration of the installation (see examples in annex D).
4.12 Critical dimensions and mass restrictions, including those related to available space (see examples in
annex D).
ISO 14644-4:2001(E)
4.13 The process and product requirements that affect the installation (see examples in annexes B and G).
4.14 The process equipment list with utility requirements (see examples in annexes D, E and H).
4.15 The maintenance requirements of the installation (see examples in annexes D and E).
4.16 The assignment of tasks for the preparation, approval, execution, supervision, documentation, statement of
criteria, basis of design, detailed design, construction, testing, commissioning and qualification (including the
performance and witnessing) of tests (see examples in annexes E and G).
4.17 The identification and evaluation of external environmental influences (see examples in annex H).
4.18 Additional information required by the particular application (see examples in annex H).
5 Planning and design
5.1 Planning procedure
5.1.1 A project plan shall be developed, in consultation with the user and all other involved parties, to define the
requirements of the products, the processes and the scope of the installation.
5.1.2 In order to determine the needs of an installation, a process equipment list shall be compiled, and shall
include the critical requirements for each piece of process equipment.
5.1.3 Diversity factors shall be defined, considering peak and average demand for each utility and environmental
control system.
NOTE A system may include multiple subsystems which require individual diversity-factor determination.
5.1.4 A contamination control concept shall be developed for each zone of an installation (see examples in
annex A).
5.1.5 The specifications as defined in clause 4 shall be reviewed and refined based on financial and timescale
requirements.
5.1.6 The project plan shall include the following elements:
a) design documentation with support calculations;
b) cost evaluation;
c) timescale evaluation;
d) an outline of anticipated project complications;
e) design options with records of advantages and disadvantages and any recommendations;
f) a review of maintenance requirements of the installation;
g) a review of the degree of flexibility to be included in the installation;
h) a review of the stand-by capacities to be included in the installation;
i) a review of the constructability of the design of the installation;
j) a quality plan.
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ISO 14644-4:2001(E)
The use of a quality system, such as the ISO 9000 family of international standards (e.g. ISO 9000 and
ISO 9001), should be considered, in conjunction with industry-specific quality assurance strategies.
5.1.7 The completed project plan shall be reviewed and agreed upon between purchaser and supplier.
5.2 Design
5.2.1 The design shall accommodate all of the relevant product and process requirements in conjunction with the
selected contamination control concept (see examples in annex A).
5.2.2 The purchaser and supplier shall formally accept the design in accordance with predetermined acceptance
criteria.
5.2.3 The design shall conform to an agreed list of requirements, such as building, environmental and safety
regulations, good manufacturing practice guidelines (e.g. ISO 14001 and ISO 14004).
The design should be reviewed at periodic stages of development, including final completion, to ensure compliance
with the specifications and the acceptance criteria.
6 Construction and start-up
6.1 Construction of an installation shall comply with the drawings and specifications.
6.2 Any changes required during the course of construction shall be checked for acceptance, approved and
documented prior to implementation of the change in accordance with a change control procedure.
6.3 Construction work, whether performed at a manufacturing location or in situ, shall observe the specific
contamination control requirements of the quality plan.
6.4 A clean construction protocol and cleaning procedures shall be developed as part of the quality plan and
enforced to achieve the specified contamination control requirements. Security and access control is essential to
maintain the clean construction protocol.
6.5 The cleaning methods and methods to determine and approve the achieved cleanliness shall be defined and
documented in the quality plan.
6.6 The cleaning of the air systems shall be specified and shall be carried out at assembly, before initial
operation and whenever rebuilding work, repair work and maintenance work are performed.
6.7 In the case of start-up of new installations or re-starting existing installations after repair or modification, final
cleaning of the cleanroom is necessary and provisions shall be made for the removal of adherent, imported or
released contamination.
6.8 Before commencing any operational activities, the complete and satisfactory function of the installation shall
be determined by tests carried out in accordance with clause 7.
NOTE In the case of packaged units, such as clean air devices, a manufacturer's certificate of compliance with the
requirements of this part of ISO 14644 may be sufficient, provided that the supplier is qualified (i.e. knowledgeable of or
competent in cleanroom requirements) and the risk of damage during transport, storage and installation can be controlled
adequately.
6.9 During acceptance testing, commissioning and initial operation, the personnel in charge of the installation
shall be trained. Testing, approval of the installation and training shall include all relevant practices for proper
cleanroom operation, maintenance and in-process control. The responsibility for providing training shall be defined.
When training is carried out, all relevant persons such as operators, maintenance and service personnel should be
included.
ISO 14644-4:2001(E)
7 Testing and approval
7.1 General
During and upon completion of the construction of an installation, an agreed series of documented tests shall be
specified and undertaken prior to operational use of the installation. Annex C gives examples of the design, testing
and approval processes.
7.2 Construction approval
A systematic range of inspections, adjustments, measurements and tests shall be carried out to ensure that each
part of the installation complies with the design requirements.
7.3 Functional approval
A series of tests and measurements shall be carried out to determine that all parts of the installation operate
together to achieve the required conditions in the "as-built" or "at-rest" states.
7.4 Operational approval
A series of tests and measurements shall be carried out to determine that the complete installation achieves the
required "operational" performance with the specified process or activity functioning, and with the specified number
of personnel present working in the agreed manner.
8 Documentation
8.1 General
Details of a completed installation (including instrumentation calibration) and all operation and maintenance
procedures shall be documented. Documents shall be made readily available to all personnel responsible for start-
up, operation and maintenance of the installation.
Such personnel should fully understand the documentation.
8.2 Record of an installation
Details of the completed installation shall be provided and shall contain:
a) a description of the installation and its function;
b) a set of final and approved performance test data, derived from the tests carried out in accordance with
clause 7 of this part of ISO 14644, recording the values of all conditions defined in the specification for the
installation and achieved during the commissioning, testing and start-up procedures;
c) a set of drawings, diagrams (e.g. layout of wiring, piping and instrumentation) and specifications describing the
completed and approved "as-built" installation and its components;
d) a list of parts and equipment and any recommendation for stocking spare parts.
8.3 Operational instructions
Each installation or system shall be provided with a clear set of operating instructions. Such operating instructions
shall contain:
a) schedules of checks and inspections to be completed prior to the start-up of an installation;
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ISO 14644-4:2001(E)
b) schedules of the acceptance range of the critical performance parameters specified;
c) procedures to start and stop the installation under normal and failure mode situations;
d) procedures to be adopted in the event of alert or action levels being reached.
8.4 Instructions for performance monitoring
Performance-monitoring of an installation is essential to demonstrate satisfactory operation. Documentation shall
include:
a) test and measurement frequency;
b) description of test and measurement methods, (or reference to standards and guidelines);
c) action plan in the event of non-compliance;
d) frequency required for assembly, analysis and retention of performance data to enable trends to be analysed.
8.5 Maintenance instructions
Maintenance shall be implemented in accordance with a specified method and programme.
Maintenance and repairs shall be carried out during the construction, commissioning, testing, start-up and normal
operation of an installation. The following items shall be considered:
a) definition of safety procedures prior to carrying out maintenance or repairs;
b) specification of maintenance actions to be taken when the acceptance range of any critical performance
parameter is exceeded;
c) agreed definition of permitted adjustments;
d) methods of making permitted adjustments;
e) methods of checking and calibrating control, safety and monitoring devices;
f) requirements for checking and replacing all wearing parts (e.g. driving belts, bearings, filters);
g) specification for cleaning of the installation or components prior to, during and after maintenance work;
h) definition of actions, procedures and tests required after maintenance is completed;
i) inclusion of any user-specific or relevant regulatory authority requirements.
8.6 Maintenance record
A documented record of any maintenance carried out upon the installation during construction, commissioning and
start-up shall be maintained. The following items shall form part of the record:
a) definition of the maintenance tasks;
b) identification and approval of personnel undertaking the maintenance;
c) date of carrying out the maintenance;
d) a condition report prior to undertaking the maintenance;
ISO 14644-4:2001(E)
e) a list of spare parts used;
f) a report upon completion of the maintenance.
8.7 Record of operation and maintenance training
A documented record of training shall be maintained. The following items shall form part of the record:
a) definition of the training content;
b) identification of personnel providing and receiving the training;
c) training date and duration;
d) a report upon each period of training as it is completed.
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ISO 14644-4:2001(E)
Annex A
(informative)
Control and segregation concepts
A.1 Contamination control zones
For economic, technical and operational reasons, clean zones are often enclosed or surrounded by further zones
of lower cleanliness classification. This can allow the zones with the highest cleanliness demands to be reduced to
the minimum size. Movement of material and personnel between adjacent clean zones gives rise to the risk of
contamination transfer, therefore special attention should be paid to the detailed layout and management of
material and personnel flow.
Figure A.1 illustrates an example of a contamination control concept. In this configuration, the clean zone would be
regarded as a more stringently controlled portion of the cleanroom.
Figure A.1 — Shell-like contamination control concept
ISO 14644-4:2001(E)
A.2 Airflow patterns
A.2.1 Cleanroom airflow patterns can be categorized as either unidirectional or non-unidirectional. When a
combination of the two is used it is frequently called mixed airflow. Airflow patterns for cleanrooms of ISO Class 5
and cleaner in operation are often unidirectional, while non-unidirectional and mixed flow is typical for cleanrooms
of ISO Class 6 and less clean in operation.
A.2.2 Unidirectional airflow may be either vertical or horizontal (see Figure A.2). Both types of unidirectional
airflow rely upon a final filtered air supply and air return inlets which are nearly opposite one another in order to
maintain the airstream in as straight a flow pattern as possible. In both designs, the important design feature is the
ability to ensure that the airflow pattern is disrupted as little as possible at the process core.
In a working plane perpendicular to the clean airflow, all positions offer the same cleanliness level. Hence,
horizontally integrated or distributed processes require vertical airflow and vertically integrated processes require
horizontal airflow. Working positions immediately adjacent to the clean air supply offer optimal contamination
control conditions, because working positions downstream of these positions may be subject to particles generated
upstream. Personnel placement should be therefore downstream of clean processing.
A.2.3 In non-unidirectional airflow cleanrooms, air flows from filter outlets located in multiple positions distributed
across the inlet plane and is returned through remote locations. Filter outlets may be distributed at equal intervals
throughout the cleanroom or clean zone or grouped over the process cores. The location of filter outlets is
important for the cleanroom performance. The final filter location may be remote, but special precautions should be
taken to avoid contamination ingress between these filters and the cleanroom (e.g. monitoring of the surface
cleanliness and airtightness of ventilation ducts and supply air inlets to avoid induction of contamination as well as
the deployment of decontamination procedures). While return air locations in non-unidirectional airflow systems are
not as critical as those in unidirectional applications, care should be taken to distribute the returns, as is done with
the supplies, to minimize dead zones within the cleanroom.
A.2.4 Mixed-airflow cleanrooms combine both unidirectional and non-unidirectional airflow in the same room.
NOTE Some special designs are available that provide protection to specific working zones by other managed airflow
techniques.
Figure A.2 gives examples that illustrate the different airflow patterns in cleanrooms. (Thermal effects are not
considered.)
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ISO 14644-4:2001(E)
a) Unidirectional airflow
b) Non-unidirectional airflow
c) Mixed airflow
Key
1 Supply air
2 Return air
Figure A.2 — Airflow patterns in cleanrooms
ISO 14644-4:2001(E)
A.3 Disturbance of unidirectional airflow
In unidirectional airflow cleanrooms, the design of physical obstacles such as the process equipment, and the
operating procedures, personnel movements and product handling, should consider basic aerodynamic
requirements to prevent serious turbulence in the vicinity of the contamination-sensitive activity. Appropriate
measures should be taken to avoid flow disturbances and cross-contamination between different work stations.
Figure A.3 shows the influence of physical obstacles (on the left) and appropriate measures for minimizing the
impact of these (on the right).
Flow obstacles causing Adjustments to equipment and behaviour
a flow disturbance to improve airflow
a) Improvement by arrangement
b) Improvement by structure
c) Improvement by personnel behaviour
d) Improvement by airflow concept
Key
1 Heat source
a
Local increase in air velocity.
Figure A.3 — Influence of personnel and objects on unidirectional airflow
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ISO 14644-4:2001(E)
A.4 Contamination control concepts
To select the proper technique for a given contamination control problem, Figures A.4 and A.5 show some different
contamination control concepts that may be considered.
The transfer of contaminants into a zone protecting a process and/or personnel can be prevented by using
aerodynamic measures, i.e. by arrangement and flow direction (Figure A.4), or by physical barriers, i.e. by both
active and passive isolation (Figure A.5), if any contact between product and operator/environment is to be
prevented.
If necessary, process exhaust should be treated to prevent contamination of outdoor environment.
Horizontal flow Vertical flow
a) Product protection
b) Personnel/environmental protection
c) Personnel/product/environmental protection
Key
1 Flow direction perpendicular to graphic plane
NOTE In particular cases (e.g. dry atmosphere, shielding and protecting gas or extreme temperatures), the gas flow routing
chosen should be adapted to the process.
Figure A.4 — Contamination control concepts using aerodynamic measures
ISO 14644-4:2001(E)
Passive system Airflow/Active system
Key
1 Personnel safety zone
2 Product protection zone
Figure A.5 — Contamination control concepts using physical segregation for product and personnel
protection
A.5 Concepts to achieve segregation of cleanrooms and clean zones
A.5.1 General
A suite of cleanrooms can consist of multiple rooms with different requirements for contamination control. The
objective of the design can be to protect the product or process, or to contain the product, and in some cases a
combination of these requirements. In order to protect cleanrooms from contamination from adjacent less clean
spaces, the cleanroom should be maintained at a higher static pressure than the adjacent spaces, or alternatively a
controlling air velocity should be established across the leakage paths between the spaces flowing from the cleaner
to the less clean space.The converse can be applied to contain a hazard. In both cases, an impervious physical
barrier can be used as an alternative.
The quantity of make-up air should be sufficient for ventilation purposes and to compensate for the leakage of air
from the boundary of the cleanrooms or clean zones and any exhaust air for other purposes.
The following comparison of three basic concepts has been prepared to facilitate the selection of a suitable
cleanroom or clean zone segregation concept.
A.5.2 Displacement concept (low pressure differential, high airflow)
A low pressure differential can effectively separate clean and less clean adjacent zones, i.e. by means of a low
turbulent "displacement" airflow, e.g. larger than 0,2 m/s (see Figure A.6).
v >0,2m/s
air
Figure A.6 — Displacement concept
Displacement airflow velocity should be typically above 0,2 m/s, from the cleaner zones towards the less clean
zones. The necessary airflow velocity should be selected considering important conditions such as physical
obstacles, heat sources, exhausts and contamination sources.
14 © ISO 2001 – All rights reserved

ISO 14644-4:2001(E)
A.5.3 Pressure differential concept (high pressure differential, low airflow)
A pressure differential exists across the barrier between the cleaner zone towards the less clean zone. A high
pressure differential between adjacent zones can be easily controlled but care is recommended to avoid
unacceptable turbulence (see Figure A.7).
The pressure differential should be of sufficient magnitude and stable to prevent reversal of airflow direction from
that intended. The pressure differential concept should be carefully considered, whether used alone or in
combination with other contamination control techniques and concepts.
The pressure differential between adjacent cleanrooms or clean zones of different cleanliness level should lie
typically in the range of 5 Pa to 20 Pa, to allow doors to be opened and to avoid unintended cross-flows due to
turbulence.
The static pressure between cleanrooms of different class, and cleanrooms and unclassified areas can be
established and maintained using various airflow balancing techniques. These include both active/automated and
passive/manual systems that are configured to adjust the relative quantities of air that are delivered and removed
from each space by the ducted air system, air transfer system and losses.
In situations when pressure differentials at the lower end of this range are accepted
...