ASTM E2217-12(2019)
(Practice)Standard Practice for Design and Construction of Aerospace Cleanrooms and Contamination Controlled Areas
Standard Practice for Design and Construction of Aerospace Cleanrooms and Contamination Controlled Areas
SIGNIFICANCE AND USE
4.1 This practice describes and defines factors to be taken into consideration when designing and fabricating a cleanroom or controlled area that is used for aerospace operations and fabrication. Following the suggestions herein should provide a facility that is more capable of meeting performance requirements and that will offer protection against contamination for objects fabricated and processed in such a facility.
SCOPE
1.1 The purpose of this practice is to provide design and construction guidelines for contamination controlled facilities used in the assembly and integration of aerospace hardware. The guidelines herein are intended to ensure that the facilities, when used properly, will meet the cleanliness requirements of aerospace hardware and processes. The objective is to limit contamination due to the deposition of particulate and molecular contaminants on flight hardware surfaces.
1.2 One cleanliness classification of a facility is the airborne particle concentrations in accordance with ISO 14644-1 and 14644-2. Airborne particle concentrations in accordance with FED-STD-209E are included for reference. This simple classification is inadequate to describe a facility that will support the assembly and integration of spacecraft. The extended duration of hardware exposure during fabrication and testing, the sensitivity of the hardware to hydrocarbons and other molecular contaminants, and the changing requirements during assembly and integration must be considered in addition to the airborne particle concentrations.
1.3 The guidelines specified herein are intended to provide facilities that will effectively restrict contaminants from entering the facility, limit contamination generated by and within the facility, and continuously remove airborne contaminants generated during normal operations. Some items of support hardware, such as lifting equipment, stands, and shoe cleaners, are addressed since these items are often purchased and installed with the facility and may require accommodation in the design of the facility.
1.4 Active filtration of molecular contaminants (such as hydrocarbons, silicones, and other chemicals) is discussed. Such active filtration of molecular contaminants may be required for the processing of highly sensitive optical devices, especially infrared and cryogenic sensors. Control of microbiological contamination is not included although HEPA (High Efficiency Particulate Air) filtration will provide some control of airborne bacteria, spores, and other viable contaminants that are typically carried on particles of sizes 0.3 μm and larger. Control of radioactive contamination and accommodation of very hazardous materials such as propellants, strong acids or caustics, or carcinogens are not addressed.
1.5 No facility will compensate for excessive contamination generated inside the facility. In addition to an effective facility design, the user must also institute a routine maintenance program (see Practice E2042) for the facility, and personnel and operational disciplines that limit the transfer of contaminants through entry doors and contaminant generation inside the facility.
1.6 This practice only addresses guidelines for contamination control in facility design. It must be implemented in compliance with all mandatory government and regulatory building and safety codes. References to related cleanroom standards and U.S. building codes and standards may be found in IEST-RP-CC012.
1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.7.1 The values given in parentheses are provided for information only and are not considered standard.
1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and det...
General Information
- Status
- Published
- Publication Date
- 30-Nov-2019
- Technical Committee
- E21 - Space Simulation and Applications of Space Technology
- Drafting Committee
- E21.05 - Contamination
Relations
- Effective Date
- 01-Dec-2019
- Effective Date
- 15-Oct-2023
- Effective Date
- 01-Apr-2020
- Effective Date
- 01-Apr-2020
- Effective Date
- 01-Apr-2020
- Refers
ASTM F24-20 - Standard Test Method for Measuring and Counting Particulate Contamination on Surfaces - Effective Date
- 01-Apr-2020
- Effective Date
- 01-Oct-2015
- Effective Date
- 01-Nov-2012
- Effective Date
- 01-Nov-2012
- Effective Date
- 01-Apr-2012
- Effective Date
- 01-Sep-2011
- Effective Date
- 01-Sep-2011
- Refers
ASTM F24-09 - Standard Method for Measuring and Counting Particulate Contamination on Surfaces - Effective Date
- 01-Apr-2009
- Effective Date
- 01-Apr-2009
- Effective Date
- 01-May-2008
Overview
ASTM E2217-12(2019), titled Standard Practice for Design and Construction of Aerospace Cleanrooms and Contamination Controlled Areas, provides comprehensive guidelines for designing and constructing cleanrooms and controlled environments used in aerospace assembly and integration. Developed by ASTM International, this standard addresses factors crucial for maintaining contamination control to ensure aerospace hardware meets stringent cleanliness requirements. By implementing the recommendations in ASTM E2217, organizations can minimize the deposition of particulate and molecular contaminants on sensitive equipment, improve facility performance, and safeguard aerospace processes from potential contamination risks.
Key Topics
- Contamination Control: The standard outlines measures to restrict contaminants from entering and being generated within cleanrooms, as well as procedures for their removal during operations.
- Cleanliness Classification: It references ISO 14644-1 and ISO 14644-2 for airborne particle concentration classifications, while noting that these criteria alone may not be sufficient for aerospace applications.
- Design Considerations: Design guidelines include material selection, airflow types (unidirectional/non-unidirectional), air change rates, filtration technologies (HEPA/ULPA), room pressurization, and process-specific requirements.
- Facility Planning: Emphasizes the importance of considering current and future operational requirements, contamination sensitivity analysis, and risk assessments during the facility planning phase.
- Material and Equipment Compatibility: Advises on the selection of abrasion-resistant, low-shedding materials and details requirements for surfaces, finishes, and cleanroom hardware to avoid outgassing or corrosion.
- Operational Controls: Highlights the necessity of routine maintenance programs, personnel discipline, and operational procedures to maintain facility cleanliness.
- Hazard and Risk Management: Recommends incorporating safety features against power failure, HVAC malfunctions, seismic events, and other hazards, while ensuring compliance with building and safety codes.
Applications
ASTM E2217-12(2019) is predominantly applied in the design and construction of cleanrooms and controlled areas for:
- Aerospace Assembly and Integration: Ensuring the assembly and integration environments for spacecraft and flight hardware are contamination-free, supporting sensitive operations such as optics and sensor integration.
- Aerospace Manufacturing Facilities: Implementing contamination controls that support various cleanroom classes as needed for manufacturing components or final system assembly.
- Testing Laboratories: Creating controlled environments for testing aerospace equipment where exposure to contaminants must be tightly managed.
- Support Hardware and Infrastructure: Specifying requirements for including items such as cranes, hoists, specialized flooring, and support equipment, ensuring these do not compromise the cleanroom’s integrity.
- Sensitive Device Processing: Addressing needs for molecular filtration in areas dealing with infrared, cryogenic, or other sensitive devices.
Related Standards
ASTM E2217 aligns with various international and national standards, enhancing its utility and interoperability across the aerospace industry:
- ISO 14644 Series: Cleanrooms and associated controlled environments - Parts 1 (classification), 2 (monitoring), 3 (test methods), and 4 (design and construction).
- IEST Standards:
- IEST-RP-CC001: HEPA and ULPA Filters
- IEST-RP-CC006, IEST-RP-CC007: Testing of Cleanrooms and Filters
- IEST-RP-CC012: Cleanroom Design Considerations
- IEST-STD-CC1246: Product Cleanliness Levels and Contamination Control Program
- FED-STD-209E: Airborne Particulate Cleanliness Classes (referenced for historical comparison).
- ASTM E2042: Practice for Cleaning and Maintaining Controlled Areas and Clean Rooms.
Summary
By following ASTM E2217-12(2019), aerospace organizations can design, construct, and operate cleanrooms that meet rigorous contamination control requirements essential for high-reliability space systems. Compliance with this standard helps protect sensitive aerospace hardware, supports quality assurance, and aligns facilities with internationally recognized cleanroom best practices.
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Frequently Asked Questions
ASTM E2217-12(2019) is a standard published by ASTM International. Its full title is "Standard Practice for Design and Construction of Aerospace Cleanrooms and Contamination Controlled Areas". This standard covers: SIGNIFICANCE AND USE 4.1 This practice describes and defines factors to be taken into consideration when designing and fabricating a cleanroom or controlled area that is used for aerospace operations and fabrication. Following the suggestions herein should provide a facility that is more capable of meeting performance requirements and that will offer protection against contamination for objects fabricated and processed in such a facility. SCOPE 1.1 The purpose of this practice is to provide design and construction guidelines for contamination controlled facilities used in the assembly and integration of aerospace hardware. The guidelines herein are intended to ensure that the facilities, when used properly, will meet the cleanliness requirements of aerospace hardware and processes. The objective is to limit contamination due to the deposition of particulate and molecular contaminants on flight hardware surfaces. 1.2 One cleanliness classification of a facility is the airborne particle concentrations in accordance with ISO 14644-1 and 14644-2. Airborne particle concentrations in accordance with FED-STD-209E are included for reference. This simple classification is inadequate to describe a facility that will support the assembly and integration of spacecraft. The extended duration of hardware exposure during fabrication and testing, the sensitivity of the hardware to hydrocarbons and other molecular contaminants, and the changing requirements during assembly and integration must be considered in addition to the airborne particle concentrations. 1.3 The guidelines specified herein are intended to provide facilities that will effectively restrict contaminants from entering the facility, limit contamination generated by and within the facility, and continuously remove airborne contaminants generated during normal operations. Some items of support hardware, such as lifting equipment, stands, and shoe cleaners, are addressed since these items are often purchased and installed with the facility and may require accommodation in the design of the facility. 1.4 Active filtration of molecular contaminants (such as hydrocarbons, silicones, and other chemicals) is discussed. Such active filtration of molecular contaminants may be required for the processing of highly sensitive optical devices, especially infrared and cryogenic sensors. Control of microbiological contamination is not included although HEPA (High Efficiency Particulate Air) filtration will provide some control of airborne bacteria, spores, and other viable contaminants that are typically carried on particles of sizes 0.3 μm and larger. Control of radioactive contamination and accommodation of very hazardous materials such as propellants, strong acids or caustics, or carcinogens are not addressed. 1.5 No facility will compensate for excessive contamination generated inside the facility. In addition to an effective facility design, the user must also institute a routine maintenance program (see Practice E2042) for the facility, and personnel and operational disciplines that limit the transfer of contaminants through entry doors and contaminant generation inside the facility. 1.6 This practice only addresses guidelines for contamination control in facility design. It must be implemented in compliance with all mandatory government and regulatory building and safety codes. References to related cleanroom standards and U.S. building codes and standards may be found in IEST-RP-CC012. 1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.7.1 The values given in parentheses are provided for information only and are not considered standard. 1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and det...
SIGNIFICANCE AND USE 4.1 This practice describes and defines factors to be taken into consideration when designing and fabricating a cleanroom or controlled area that is used for aerospace operations and fabrication. Following the suggestions herein should provide a facility that is more capable of meeting performance requirements and that will offer protection against contamination for objects fabricated and processed in such a facility. SCOPE 1.1 The purpose of this practice is to provide design and construction guidelines for contamination controlled facilities used in the assembly and integration of aerospace hardware. The guidelines herein are intended to ensure that the facilities, when used properly, will meet the cleanliness requirements of aerospace hardware and processes. The objective is to limit contamination due to the deposition of particulate and molecular contaminants on flight hardware surfaces. 1.2 One cleanliness classification of a facility is the airborne particle concentrations in accordance with ISO 14644-1 and 14644-2. Airborne particle concentrations in accordance with FED-STD-209E are included for reference. This simple classification is inadequate to describe a facility that will support the assembly and integration of spacecraft. The extended duration of hardware exposure during fabrication and testing, the sensitivity of the hardware to hydrocarbons and other molecular contaminants, and the changing requirements during assembly and integration must be considered in addition to the airborne particle concentrations. 1.3 The guidelines specified herein are intended to provide facilities that will effectively restrict contaminants from entering the facility, limit contamination generated by and within the facility, and continuously remove airborne contaminants generated during normal operations. Some items of support hardware, such as lifting equipment, stands, and shoe cleaners, are addressed since these items are often purchased and installed with the facility and may require accommodation in the design of the facility. 1.4 Active filtration of molecular contaminants (such as hydrocarbons, silicones, and other chemicals) is discussed. Such active filtration of molecular contaminants may be required for the processing of highly sensitive optical devices, especially infrared and cryogenic sensors. Control of microbiological contamination is not included although HEPA (High Efficiency Particulate Air) filtration will provide some control of airborne bacteria, spores, and other viable contaminants that are typically carried on particles of sizes 0.3 μm and larger. Control of radioactive contamination and accommodation of very hazardous materials such as propellants, strong acids or caustics, or carcinogens are not addressed. 1.5 No facility will compensate for excessive contamination generated inside the facility. In addition to an effective facility design, the user must also institute a routine maintenance program (see Practice E2042) for the facility, and personnel and operational disciplines that limit the transfer of contaminants through entry doors and contaminant generation inside the facility. 1.6 This practice only addresses guidelines for contamination control in facility design. It must be implemented in compliance with all mandatory government and regulatory building and safety codes. References to related cleanroom standards and U.S. building codes and standards may be found in IEST-RP-CC012. 1.7 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.7.1 The values given in parentheses are provided for information only and are not considered standard. 1.8 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and det...
ASTM E2217-12(2019) is classified under the following ICS (International Classification for Standards) categories: 13.040.35 - Cleanrooms and associated controlled environments; 49.020 - Aircraft and space vehicles in general. The ICS classification helps identify the subject area and facilitates finding related standards.
ASTM E2217-12(2019) has the following relationships with other standards: It is inter standard links to ASTM E2217-12, ASTM E1548-23, ASTM E1235-12(2020)e1, ASTM E1235-12(2020), ASTM E1234-12(2020), ASTM F24-20, ASTM F24-09(2015), ASTM E1235-12, ASTM E1234-12, ASTM F50-12, ASTM E1216-11, ASTM E2088-06(2011), ASTM F24-09, ASTM E1548-09, ASTM E1235-08. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ASTM E2217-12(2019) is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E2217 − 12 (Reapproved 2019)
Standard Practice for
Design and Construction of Aerospace Cleanrooms and
Contamination Controlled Areas
This standard is issued under the fixed designation E2217; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope required for the processing of highly sensitive optical devices,
especially infrared and cryogenic sensors. Control of micro-
1.1 The purpose of this practice is to provide design and
biological contamination is not included although HEPA(High
construction guidelines for contamination controlled facilities
Efficiency Particulate Air) filtration will provide some control
used in the assembly and integration of aerospace hardware.
of airborne bacteria, spores, and other viable contaminants that
The guidelines herein are intended to ensure that the facilities,
are typically carried on particles of sizes 0.3 µm and larger.
when used properly, will meet the cleanliness requirements of
Control of radioactive contamination and accommodation of
aerospace hardware and processes. The objective is to limit
very hazardous materials such as propellants, strong acids or
contamination due to the deposition of particulate and molecu-
caustics, or carcinogens are not addressed.
lar contaminants on flight hardware surfaces.
1.5 No facility will compensate for excessive contamination
1.2 Onecleanlinessclassificationofafacilityistheairborne
generated inside the facility. In addition to an effective facility
particle concentrations in accordance with ISO 14644-1 and
design, the user must also institute a routine maintenance
14644-2. Airborne particle concentrations in accordance with
program (see Practice E2042) for the facility, and personnel
FED-STD-209E are included for reference. This simple clas-
and operational disciplines that limit the transfer of contami-
sification is inadequate to describe a facility that will support
nants through entry doors and contaminant generation inside
the assembly and integration of spacecraft. The extended
the facility.
duration of hardware exposure during fabrication and testing,
the sensitivity of the hardware to hydrocarbons and other
1.6 This practice only addresses guidelines for contamina-
molecular contaminants, and the changing requirements during
tion control in facility design. It must be implemented in
assembly and integration must be considered in addition to the
compliance with all mandatory government and regulatory
airborne particle concentrations.
building and safety codes. References to related cleanroom
standards and U.S. building codes and standards may be found
1.3 The guidelines specified herein are intended to provide
in IEST-RP-CC012.
facilities that will effectively restrict contaminants from enter-
ing the facility, limit contamination generated by and within
1.7 The values stated in SI units are to be regarded as
the facility, and continuously remove airborne contaminants
standard. No other units of measurement are included in this
generated during normal operations. Some items of support
standard.
hardware, such as lifting equipment, stands, and shoe cleaners,
1.7.1 The values given in parentheses are provided for
are addressed since these items are often purchased and
information only and are not considered standard.
installed with the facility and may require accommodation in
1.8 This standard does not purport to address all of the
the design of the facility.
safety concerns, if any, associated with its use. It is the
1.4 Active filtration of molecular contaminants (such as
responsibility of the user of this standard to establish appro-
hydrocarbons, silicones, and other chemicals) is discussed.
priate safety, health, and environmental practices and deter-
Such active filtration of molecular contaminants may be
mine the applicability of regulatory limitations prior to use.
1.9 This international standard was developed in accor-
dance with internationally recognized principles on standard-
This practice is under the jurisdiction of ASTM Committee E21 on Space
Simulation andApplications of Space Technology and is the direct responsibility of
ization established in the Decision on Principles for the
Subcommittee E21.05 on Contamination.
Development of International Standards, Guides and Recom-
Current edition approved Dec. 1, 2019. Published January 2020. Originally
mendations issued by the World Trade Organization Technical
approved in 2002. Last previous edition approved in 2012 as E2217 – 12. DOI:
10.1520/E2217-12R19. Barriers to Trade (TBT) Committee.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E2217 − 12 (2019)
2. Referenced Documents IEST-STD-CC1246 Product Cleanliness Levels and Con-
2 tamination Control Program
2.1 ASTM Standards:
2.4 U.S Government Standards:
E595 Test Method for Total Mass Loss and Collected Vola-
FED-STD-209E Airborne Particulate Cleanliness Classes in
tile Condensable Materials from Outgassing in a Vacuum
Cleanrooms and Clean Zones
Environment
E1216 Practice for Sampling for Particulate Contamination
2.5 Other Publications:
by Tape Lift
Procedural Standards for Certified Testing of Cleanrooms,
E1234 Practice for Handling, Transporting, and Installing
National Environmental Balancing Bureau (NEBB)
Nonvolatile Residue (NVR) Sample Plates Used in Envi-
ronmentally Controlled Areas for Spacecraft 3. Terminology
E1235 Test Method for Gravimetric Determination of Non-
3.1 Definitions:
volatile Residue (NVR) in Environmentally Controlled
3.1.1 aerosol, n—a gaseous suspension of fine solid or
Areas for Spacecraft
liquid particles.
E1548 Practice for Preparation ofAerospace Contamination
3.1.2 airfilters:
Control Plans
3.1.2.1 HEPA (High Effıciency Particulate Air) filter, n—a
E2042 Practice for Cleaning and Maintaining Controlled
particulate air filter having a minimum particle collection
Areas and Clean Rooms
efficiency of 99.97 % of particles greater than 0.3 µm in
E2088 Practice for Selecting, Preparing, Exposing, andAna-
accordance with IEST-RP-CC001.
lyzing Witness Surfaces for Measuring Particle Deposi-
3.1.2.2 ULPA (Ultra Low Penetration Air) filter, n—a par-
tion in Cleanrooms and Associated Controlled Environ-
ticulate air filter having a minimum particle collection effi-
ments
ciencyof99.999 %ofparticlesofsizesequaltoandlargerthan
F24 Test Method for Measuring and Counting Particulate
0.12 µm.
Contamination on Surfaces
F25 Test Method for Sizing and Counting Airborne Particu-
3.1.2.3 prefilters, n—air filters that are installed upstream of
late Contamination in Cleanrooms and Other Dust-
the HEPA or ULPA filters.
Controlled Areas
3.1.2.4 Discussion—These usually consist of rough filters
F50 Practice for Continuous Sizing and Counting of Air-
and medium efficiency filters that remove larger particles than
borne Particles in Dust-Controlled Areas and Clean
are removed by the HEPA and ULPA filters; They are used to
Rooms Using Instruments Capable of Detecting Single
reduce the number of particles trapped on the high efficiency
Sub-Micrometre and Larger Particles
filters, thereby extending the lifetimes of the HEPAand ULPA
2.2 ISO Standards:
filters.
ISO 14644-1 Cleanrooms and Associated Controlled Envi-
3.1.3 airflow:
ronments Part 1: Classification of Air Cleanliness
3.1.3.1 unidirectional airflow, n—controlled airflow through
ISO 14644-2 Cleanrooms and Associated Controlled Envi-
the entire cross-section of a cleanroom or clean zone with a
ronments Part 2: Specifications for Testing and Monitor-
steady velocity and approximately equal streamlines.
ing to Prove Continued Compliance with ISO 14644-1
ISO 14644-3 Cleanrooms and Associated Controlled Envi-
3.1.3.2 Discussion—The airflow in a cleanroom may be
ronments Part 3: Test Methods either vertical down-flow or horizontal with air leaving the
ISO 14644-4 Cleanrooms and Associated Controlled Envi-
room either through nearly continuous floor or wall vents.
ronments Part 4: Design, Construction and Start-up Equipmentandpersonnelintheroomwillcauseairturbulence,
but the airflow is still considered unidirectional.
2.3 Institute of Environmental Science and Technology
3.1.3.3 nonunidirectional airflow, n—air distribution where
Standards:
the supply air entering the cleanroom or clean zone mixes with
IEST-RP-CC001 HEPA and ULPA Filters
the internal air by means of induction.
IEST-RP-CC006 Testing Cleanrooms
IEST-RP-CC007 Testing ULPA Filters
3.1.3.4 Discussion—Air typically enters through registers
IEST-RP-CC012 Considerations in Cleanroom Design
distributed around the room above the working area and exits
IEST-RP-CC022 Electrostatic Charge in Cleanrooms and
through registers at floor level.
Other Controlled Environments
3.1.3.5 mixed airflow, n—air distribution in a cleanroom or
IEST-RP-CC034 HEPA and ULPA Filter Leak Tests
clean zone in which the airflow is a mixture of both unidirec-
tional and nonunidirectional.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on This replaces MIL-STD-1246C which is inactive.
the ASTM website. This standard was cancelled 29 Nov. 2001 and is replaced by ISO 14644-1 and
Available from International Organization for Standardization (ISO), 1, ch. de ISO 14644-2. Copies of FED-STD-209E are available from the Institute of
la Voie-Creuse, CP 56, CH-1211 Geneva 20, Switzerland, http://www.iso.org. Environmental Sciences and Technology, 940 East Northwest Highway, Mount
Available from Institute of Environmental Sciences and Technology (IEST), Prospect, IL 60036, and from U.S. government sources.
Arlington Place One, 2340 S. Arlington Heights Rd., Suite 100, Arlington Heights, National Environmental Balancing Bureau, 8575 Grovemont Circle,
IL 60005-4516, http://www.iest.org. Gaithersburg, MD 20877-4121. http://www.nebb.org/contact/.
E2217 − 12 (2019)
3.1.3.6 Discussion—Different locations in a cleanroom can 3.1.11.1 Discussion—Usually, the charge flows through a
have different types of airflow. This is especially true in large spark between two bodies at different electrostatic potentials as
cleanrooms. A cleanroom design may include mixed airflow. they approach one another.
3.1.4 changing room, n—room where people using a clean-
3.1.12 electromagnetic interference (EMI), n—interference,
room change into, or out of, cleanroom apparel.
generally at radio frequencies, that is generated inside systems,
as contrasted to radio-frequency interference coming from
3.1.5 cleanroom,n—aspecializedenclosedroomemploying
control over the airborne particle concentrations, temperature, sources outside a system.
humidity, pressure, molecular contaminants, and operations.
3.1.13 facility (clean facility), n—the total real property
3.1.5.1 cleanroom (alternate), n—a room in which the
required to accomplish the cleanroom functions.
concentration of airborne particles, temperature, humidity,
3.1.13.1 Discussion—This includes all the buildings,
pressure, molecular contaminants, and operations are
cleanrooms, offices, laboratories, storage areas, HVAC
controlled, and which is constructed and used in a manner to
equipment, and other support areas for operations and person-
minimize the introduction, generation, and retention of con-
nel.
taminants inside the room.
3.1.14 gas phase adsorber cell, n—a modular container for
3.1.6 cleanroom occupancy states:
anadsorbenttotrapcontaminantgasesfromairandothergases
3.1.6.1 as-built, adj—condition where the installation is
used in processing.
complete with all services connected and functioning but with
no equipment, flight hardware and materials, or personnel
3.1.15 installation, n—cleanroom or one or more clean
present.
zones, together with all associated structures, air-treatment
systems, services, and utilities.
3.1.6.2 Discussion—For contractual purposes, the parties
involved should have an agreement that defines this state.
3.1.16 macroparticle, n—a particle with an equivalent di-
3.1.6.3 at-rest, adj—conditionwheretheinstallationiscom-
ameter greater than 5 µm.
plete with equipment installed and operating in a manner
3.1.16.1 Discussion—The M descriptor defines the mea-
agreed upon by the customer and supplier, but with no
sured or specified concentrations of macroparticles per cubic
personnel present.
meter of air. This is defined in ISO 14644-1.
3.1.6.4 operational, adj—condition where the installation is
3.1.17 monitoring, n—observations made by measurement
functioning in the specified manner, with the specified number
in accordance with a defined method and plan to provide
of personnel present and working in the agreed upon manner.
evidence of the performance of an installation.
3.1.7 clean zone, n—dedicated space in which the concen-
tration of airborne particles is controlled, which is constructed 3.1.18 nonvolatile residue (NVR), n—contaminant residue
and used in a manner to minimize the introduction, generation, without distinct dimensions. It typically consists of
and retention of particles inside the zone, and in which other hydrocarbons, silicones, and other higher molecular weight
relevant parameters, for example, temperature, humidity, species deposited through condensation, direct contact trans-
pressure, and molecular contaminants, are controlled as neces- mission (that is, fingerprints) or as residue remaining after
sary. evaporation of a liquid.
3.1.8 contaminant, n—any particulate, molecular, non-
3.1.19 outgassing, n—the evolution of gas from a material,
particulate, and biological entity that can adversely affect the
usually in a vacuum. Outgassing also occurs in a higher
product or process.
pressure environment.
3.1.9 contaminant deposition, n—particulate and molecular
3.1.19.1 Discussion—While outgassing is typically consid-
contaminants that form on surfaces resulting from processes
ered a vacuum phenomenon, some materials, such as polyvinyl
such as fallout, condensation, electrostatic attraction, and other
chloride, contain volatile components, such as plasticizers, that
mechanisms.
will diffuse from bulk materials and evaporate under standard
3.1.10 contamination controlled area, n—a specialized en-
temperatures and pressures. These volatile components are
closed facility employing control over the particulate matter in
highly contaminating to sensitive aerospace hardware.
air, temperature, and humidity that may not meet the require-
3.1.20 particle fallout, n—particulate matter that accumu-
mentsofISO14644-1orFED-STD-209EbecauseofnoHEPA
lates on surfaces due to gravity settling. This matter is often of
or ULPA type filters.
a particulate size larger than that measured by airborne particle
3.1.10.1 Discussion—For example, without a final stage of
counters.
HEPAorULPAfilters,theairborneparticleconcentrationsmay
3.1.21 radio-frequency interference (RFI), n—interference
only meet ISO Class 8.5 (FS209E Class 300 000) for particles
from sources of energy outside a system or systems, as
equal to and greater than 0.3 µm but may meet ISO Class 8
contrasted from electromagnetic interference generated inside
(FS209E Class 100 000) for particles equal to and greater than
systems.
5 µm.
3.1.11 electrostatic discharge (ESD), n—the rapid, sponta- 3.1.22 test aerosol, n—a gaseous suspension of solid or
neous transfer of electrostatic charge induced by a high liquid particles, or both, with known and controlled size
electrostatic field. distribution and concentration.
E2217 − 12 (2019)
4. Significance and Use bly and integration. Further information on determining clean-
liness requirements is found in Practice E1548.
4.1 This practice describes and defines factors to be taken
5.3.4 Cost analyses are necessary to evaluate the alternative
into consideration when designing and fabricating a cleanroom
design approaches.
or controlled area that is used for aerospace operations and
fabrication. Following the suggestions herein should provide a
6. General Design Practice
facility that is more capable of meeting performance require-
ments and that will offer protection against contamination for
6.1 Design Considerations:
objects fabricated and processed in such a facility.
6.1.1 The purpose of a cleanroom is to protect the hardware
and processes. Ideally, the cleanroom should be designed
5. Planning and Development of Performance and Design
around the processes and operations to be performed in the
Requirements
cleanroom. However, a typical situation involves designing a
multipurpose cleanroom. Each space system is unique and may
5.1 Purpose of a Cleanroom—A cleanroom provides three
have different requirements. Consideration should be given to
functions for a process:
including multiple requirements in the design. This can be
5.1.1 Clean air with temperature and humidity control,
accomplished in the initial construction or by allowing for the
5.1.2 Control of contaminants generated within the room,
inclusion of additional performance in the future when needed.
and
Cost-benefit analyses should be used to evaluate alternative
5.1.3 Control of the transfer of contaminants from outside
designs.
the room.
6.1.2 Spacecraft assembly and integration are usually con-
5.2 Planning—The first step is to determine the types of
sidered batch processes. Operations are performed sequentially
operations to be performed in the cleanroom and cleanliness
on each spacecraft, and different operations may have different
requirements of the hardware to be processed. Alternative
cleanliness requirements. Design of the clean facility should
designs are studied and preliminary requirements are devel-
consider these different operations and requirements.
oped during the planning phase.
6.2 ISO 14644-4 and IEST-RP-CC012 provide guidelines
5.3 Performance and Design Requirements:
for the design and construction of cleanrooms. The cognizant
5.3.1 The cognizant program materials and processes engi-
contamination control and facility engineers should do detailed
neer or contamination control engineer and facility engineer
design and operational analyses to select the design that meets
determine the requirements for a cleanroom or contamination-
the spacecraft processing requirements.
controlled area. These requirements may include, but are not
6.3 Clean Zones:
limited to the following:
6.3.1 Under some circumstances, cleanliness requirements
5.3.1.1 Maximum allowable airborne particle concentra-
can be achieved using inexpensive localized controls such as
tions in the operational condition,
soft wall enclosures (clean tents) and portable hard-walled
5.3.1.2 Types of airflow,
enclosures. These can provide either unidirectional or
5.3.1.3 Room air change rates or air velocities,
nonunidirectional, filtered airflow.They must be located within
5.3.1.4 Maximum allowable particle deposition,
afacilitythatprovidesthenecessarytemperature,humidityand
5.3.1.5 Maximum allowable airborne and surface concen-
molecularcontaminantcontrolsrequiredtosupporttherequire-
trations of molecular contaminants,
ments for the hardware unless they have their own HVAC
5.3.1.6 Types of air filters,
system.When required, self-contained temperature and humid-
5.3.1.7 Need for and properties of piped in fluids (com-
ity control can be provided.
pressed air, nitrogen, helium, water, and so forth),
6.3.2 Air curtains and other methods of controlling air
5.3.1.8 Need for built-in equipment (cranes, platforms,
distribution can be used to protect clean zones from airborne
hoists, and so forth),
contaminants.
5.3.1.9 Overall layout and process flow,
6.3.3 Operations and procedures can be controlled to reduce
5.3.1.10 EMI and RFI requirements, and
contamination from people and activities in the specified clean
5.3.1.11 ESD requirements.
zone.
5.3.2 The cleanroom and clean facility requirements are
6.4 Hazards:
based on the cleanliness requirements of the hardware to be
6.4.1 Cleanroom facility design should consider potential
processed and the types of operations to be performed in the
cleanroom. The requirements should consider, as much as hazards to personnel and products. Risk-cost-benefit analyses
should be performed to determine the design features that are
possible, future changes in requirements so that the facility
does not become obsolete in a short time. Some enhancements required to achieve acceptable risks. Operational solutions to
meeting the risk requirements should be considered in coordi-
do not result in a significant increase in cost if implemented in
the original design. Another approach is designing to allow nation with design solutions.
enhancements to be added later if required.
6.4.2 Equipment failures and human errors can result in
5.3.3 A contamination sensitivity analysis may be per- damagetohardwareandinjuriestopersonnel.Itisimportantto
formed and contaminant allocations derived to determine considersinglepointfailuremodes,equipmentandhuman,and
facility cleanliness requirements during each phase of assem- their possible effects on products, processes, and personnel.
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Designing so that two or more failures are required to result in 7.1.1.2 Filter Face Velocity—Filterfacevelocityisspecified
a system failure reduce the probability for a system failure. in unidirectional flow cleanrooms. Typical filter face velocities
6.4.3 Electrical Power—Electrical power failures will shut are 0.46 to 0.56 m/s (90 to 110 ft/min). Lower face velocities
down equipment, instrumentation, and lighting. Critical items may not be effective in removing airborne particles but may
should have an alternative source of power. The switch from reduce air turbulence. Higher face velocities may stress the
the main power source to the alternative power source may filters and cause excessive air turbulence.
result in a short time of power interruption and transient
7.1.1.3 Unidirectional Flow—Filter face velocities must be
effects. Equipment and processes should be able to survive balanced to within 610 % to achieve effective, uniform,
these effects. Equipment that is not critical should automati-
unidirectional airflow. The configuration of the room and the
cally shut down in a safe mode. Restart when power resumes location of large equipment must also be carefully considered
should not damage equipment or processes. Manual restart
to prevent dead zones, turbulence, and reverse flow.A“smoke
should be considered to ensure that the equipment is operating test,” in which a cleanroom compatible white vapor is released
properly.
from a capsule or a smoke generator to indicate air currents,
6.4.4 Cooling Water—Cooling water failure can shut down may be useful to reveal problem areas. Water droplets have
many types of equipment. Equipment should be able to shut
been used to avoid permanent contamination from solid and
down safely without damage to the equipment or to the
liquidaerosols.Stripsofthinmetallizedfilmsmayalsobeused
process.
to determine the directions of flowing air.
6.4.5 HVAC—The shut down of the HVAC system or
7.1.2 Positive Pressure:
failures of components such as filters, fans, and air condition-
7.1.2.1 A positive pressure must be maintained over the
ing should be evaluated for effects on hardware and processes.
pressure in adjacent areas of lesser cleanliness to prevent
Bothfacilitydesignandoperationalproceduresolutionsshould
infiltration of external contamination through leaks and during
be considered.
the opening and closing of personnel doors. Pressure differen-
6.4.6 Seismic and Weather Events—Severe natural events,
tials in the range of 5 to 20 Pa (0.02 to 0.08 in. of water) are
such as earthquakes and hurricanes, should be considered in
frequentlyused.Whereseveralcleanroomsofvaryinglevelsof
the design of clean facilities. The probability of occurrences
cleanliness are joined as one complex, a positive pressure
and severities should be considered. Design should consider
hierarchy of cleanliness levels should be maintained, including
various levels of severity. One level is the ability for the
airlocks and changing rooms.
hardware and processes to survive with no damage or down
7.1.2.2 Higher pressures may be required when outside air
time.The next level is the ability for the facility to survive, but
pressures exceed inside pressures and result in an increased
some damage to hardware and processes is allowed. The third
leakage into the cleanroom. An example is higher pressures
level is that damage to hardware, processes, and facility
resulting from high winds.
structure is allowed, but personnel are protected.
7.1.2.3 When hazardous materials, such as propellants and
some biological materials, are being processed, it is necessary
7. Detail Design Guidelines
to maintain the room at a lower pressure than surrounding
7.1 Airflow and Pressure:
rooms. This is necessary to reduce the probability of the
7.1.1 Airflow Parameters—The airflow patterns and veloci-
hazardous material escaping from the room. The design of
ties and room air change rates in a cleanroom affects the class
facilities for the handling of hazardous materials must consider
of cleanliness that can be maintained during a given operation.
the required operations to be performed as well as the type of
Non-unidirectional flow cleanrooms rely on air dilution to
hazards involved.
continuously remove contaminants generated within the room.
7.2 Materials of Construction:
Unidirectional flow is more effective in continuously sweeping
7.2.1 General Materials Selection—Cleanrooms must be
particles from the air, but must be properly balanced and
constructed of abrasion resistant, non-shedding materials. Con-
maintained with associated higher airflows and thus higher
ventional materials of construction such as wood, carpet, flat
operating costs.
latex paint, and acoustic tile shed particles continuously during
7.1.1.1 Air Change Rate—The desired air change rate is
their life and are not acceptable for use in cleanrooms.
based on the required cleanliness class of the room air under
operational conditions and the generation of contaminants
NOTE 1—Materials and equipment specified for use in cleanrooms are
(density of operations) expected in the room. The level and
sometimes described as compatible with or meeting the requirements of a
types of activities in the room affect the numbers of particles
particular class of cleanroom air per ISO 14644-1 or FED-STD-209.
Thesedocumentsonlyapplytoconcentrationsofairborneparticlesanddo
generated. Five to twenty air changes per hour are typical for
not contain any requirements for materials and equipment.
a large, low density nonunidirectional airflow cleanroom. The
lower the class of air for operational conditions, the greater the 7.2.2 Outgassing—Outgassing from materials is a potential
number of air changes is required to remove sufficient particles contaminantforspacecraft.Materialsofconstructionshouldbe
to meet requirements. In unidirectional flow cleanrooms, the selected to minimize outgassing and VCM at the expected
air change rate is a result of the required filter face velocity and operating temperatures in the cleanroom. Additional require-
the size of the room. The design may allow for variable air ments may be added if the spacecraft contains components that
change rates. This can be used to reduce electrical power have specific, known sensitivities. Materials maybe selected
consumption when the process does not require the high air based on the Test Method E595 screening test, and existing
change rates or when the cleanroom is not being used. databases for spacecraft materials may be used. However,
E2217 − 12 (2019)
some materials suitable for use at normal cleanroom tempera- laminate, including melamine laminate computer flooring, is
tures will decompose when subjected to the 125 °C test also acceptable. These materials are also available with static-
temperature. Performing the Test Method E595 test at a lower dissipative additives. Vinyl flooring may be unacceptable in
temperature, such as 65 °C, has been successful for the some aerospace cleanrooms due to the presence of plasticizers.
screening of cleanroom materials. Compatibility with solvents and chemicals to be used in the
7.2.3 Cleaning—Due to the frequent cleaning performed on room must be considered.
cleanroom surfaces, materials that are hydrophilic or degrade
7.4.1.2 Coving—A coving or fillet seal should be used
in water are generally unacceptable. between the floor and the wall. A radius of 25 mm (1 in.) or
7.2.4 Textured Surfaces—All materials shall have a smooth,
greater is recommended. This may be provided in a troweled
cleanable finish. Textured surfaces should be limited to those epoxy installation using a cove filler. Cleanrooms where
required for safety reasons (such as floors).Textures used must
hazardous chemicals are used may require special coving for
be compatible with planned cleaning methods. spill containment.
7.2.5 Preferred Materials—Uncoated materials recom-
7.4.1.3 Floor Treatments—Floors should never be waxed.
mendedforuseincleanroomsincludestainlesssteels,Formica,
Acrylic floor coatings may be used for static dissipation in
fluoropolymers, polypropylene, polyester, and anodized alumi-
controlled areas or ISO Class 8 (FS209E class 100 000)
num. Bare polished or brushed aluminum may be acceptable
cleanrooms. Thesematerialswillwearwithtrafficandmustbe
provided it is protected from exposure to relative humidities
reapplied periodically. Reapplication must be performed only
above 60 %. Properly anodized aluminum is recommended to
on an off shift, with cleanroom hardware and work surfaces
control corrosion and reduce particle generation.
covered and protected and flight hardware removed.
7.2.6 Electrostatic Discharge (ESD)—Many of the non-
7.4.1.4 Floor Loading—Floors and floor finishes must be
metallic materials suitable for use in a cleanroom will also
designed to withstand anticipated floor loading from heavy
generate an electrostatic charge. Precautions must be taken in
equipmentsuchasforklifts,personnellifts,andflighthardware
facility design and operations to prevent damage to ESD
transporters.
sensitive equipment from facility materials of construction.
7.4.2 Walls—Conventional wood construction is not recom-
7.2.7 Excluded Materials—Materials that are unacceptable
mended for cleanrooms because the expansion and contraction
for use in cleanrooms include wood, cork, carpet, fabric
of the wood will cause leaks to develop over time and may
curtains, exposed gypsum board, exposed plaster, and acoustic
crack some paints. Because cleanrooms are generally main-
tile. Steel and other non-corrosion resistant metals must be
tained at a lower humidity than conventional office or manu-
painted or treated to prevent corrosion. Zinc and cadmium
facturing areas, all walls must incorporate a moisture barrier to
treated steels are not recommended for use in spacecraft
prevent humidity from sweating through the walls. Prefabri-
cleanrooms since particles released from these materials are
cated walls containing insulation, utilities (such as electrical
unstable in a vacuum. Cadmium is toxic and is being removed
wiring), and factory applied cleanroom compatible finishes
from use per federal mandate.
may be suitable.
7.4.2.1 Wall Finishes—Inexpensive latex wall paints will
NOTE 2—Fabrics impregnated with low outgassing, cleanable
polymers, such as fluorocarbons, are acceptable in cleanrooms. These are powder over time and are unacceptable in cleanrooms.Accept-
frequently used as movable walls and other enclosures.
ablewallfinishesincludeepoxypaint,polyester,somelatex,or
baked enamel, of a semi-gloss or gloss type.
7.3 Materials Application:
7.4.2.2 Impact Protection—All exposed corners and high
7.3.1 Surface Preparation—Propersurfacepreparationprior
traffic areas, such as entry airlocks, should have stainless steel
totheapplicationofapaintorcoatinginacleanroomiscritical
facings or guards to prevent impact damage to the wall. Corner
to the success of the application. The manufacturer’s instruc-
guards should extend from the floor to at least the 120 mm
tions must be followed precisely, including all precleaning and
(4 ft) height.
surface texturing. For applications such as troweled epoxy
flooring, only experienced and qualified contractors should be 7.4.2.3 Colors—Walls and ceilings shall be soft white,
ivory, or other pale reflective color. Conventional epoxy colors
used.
7.3.2 Corrosion Protection—All cleanroom materials and such as gray are acceptable for floors. There is a common
misconception that all cleanroom surfaces must be painted
equipment must be protected from corrosion prior to and
during installation. At no time should cleanroom interior white.Although this may improve the illumination in the room
and the ease of inspection, some color variety is recommended
material, equipment, ducts, or HVAC system components be
stored outdoors without proper protection. to help relieve fatigue and eye strain.
7.4.3 Ceiling Materials—The minimum acceptable ceiling
7.4 Enclosure:
material is a painted gypsum board or a suspended polyester
7.4.1 Floors—All cleanroom floors must, as a minimum,
film-coated panel. Suspended panels must be clipped or sealed
provide a complete air seal and vapor barrier. Cleanrooms built
in place to prevent movement due to air pressure changes. For
over non-humidity-controlled basements, as well as those on
rooms cleaner than ISO Class 8 (FS209E Class 100 000), full
exposed or slab foundation, must protect the floor treatment or
polyester film panels or continuous painted ceiling should be
paint from moisture permeation.
7.4.1.1 Floor Finishes—The preferred floor finish for aero-
space cleanrooms is a troweled epoxy. A primer must be used
to ensure proper adhesion to the base material. Melamine Charleswater Statguard has been found to be acceptable.
E2217 − 12 (2019)
used. In unidirectional downflow cleanrooms, the ceiling will 7.5.1 Vibration Sources—Vibration sources inside or near a
be nearly 100 % filter coverage. cleanroom will enhance particle release inside the room and
under severe conditions may cause leaks in filters and duct-
7.4.4 Doors—All regular entry doors must enter through
work. Heavy equipment including the HVAC system compo-
airlocks. Emergency exit doors must meet all of the following
nents and house vacuum system must be vibration isolated.
requirements and should incorporate crash-bar mechanisms (or
Cleanrooms are incompatible with vibration and shock testing
similar emergency opening mechanism) with alarms for exit
equipment. Location of a cleanroom directly adjacent to heavy
only. Emergency exit doors must be locked to exclude entry
presses, major roadways, or loading docks that see heavy truck
from the outside.
traffic, and other sources of vibration and shock may increase
7.4.4.1 Door Features—All doors must include airtight
contaminant generation in the cleanroom.
seals. Neoprene seals are generally acceptable, but other
7.5.2 Air Intake Location—The air intake for the cleanroom
materials, such as fluoroelastomers, may be appropriate for
makeup air must be carefully located to prevent overloading of
some applications that require chemical resistance or exposure
filters or ingestion of contaminating gases that the filters will
to large temperature extremes. Large roll-up equipment doors
not remove. Cleanroom air intakes should not be located near
may require inflatable seals to maintain room pressurization.
loading docks, traffic lanes, or other areas where internal
Brush-type door seals should not be used. Foam rubber door
combustion engine powered vehicles may drive through or
sealsarenotrecommendedasthesehavebeenfoundtoquickly
idle. Exhausts from diesel engines contain large quantities of
deteriorate and shed particles or chunks of material. All
molecular and particulate contaminants. The air intakes should
personnel doors and swinging equipment doors must include
not be located near the exhaust locations of other processing
self-closing mechanisms.
facilities.
7.4.4.2 High Bay Doors—Sliding panel doors are recom-
7.5.3 Support Services—Access for the repair and mainte-
mendedforhighbayentryratherthanroll-updoors.Horizontal
nance of support services, such as utilities, fluid systems, and
opening sliding doors are preferred to vertical (lift up) sliding
vacuum pumps, should be located outside the cleanroom so
doors because they have fewer horizontal surfaces to collect
that cleanroom operations and hardware cleanliness are not
dust. If a roll-up door must be used, cleanability of the door
affected.
joints must be considered. In some applications, a heavy-duty
7.6 Heating Ventilation and Air Conditioning (HVAC) Sys-
laminated fabric door may be acceptable if it can withstand the
tem:
internal room pressure. All motors, chains, and gear mecha-
7.6.1 The cleanroom HVAC system must be designed and
nisms must be enclosed as much as possible to contain
sized to maintain the required particulate cleanliness,
lubricants and debris.Amaintenance and cleaning schedule for
temperature, humidity, and positive pressure at the expected
these large doors must be established.
outside environmental extremes and during the worst case
7.4.4.3 Interlocks—Interlocks are recommended for airlock
expected use operations. Rapid recovery from upset conditions
door sets to prevent opening of both doors simultaneously. For
such as door openings and contaminant generating events is
equipment airlocks, an indicator light inside the cleanroom is
also a consideration. The quality of outside air in the facility
recommended to show when the outside door is open.
location must be considered when selecting, sizing, and ser-
7.4.5 Windows—Windows are recommended in aerospace
vicing filters. Atmospheric upset conditions have occurred
cleanrooms unless prohibited for security reasons. Windows
because of fires, volcanic eruptions, and chemical spills.
should be placed to permit viewing of the hardware and
7.6.2 Recirculation—Due to the high cost of conditioning
operations in order to minimize the need for non-production
outside air, and sizing of blowers to pass air through the filter
personnel to enter the cleanroom. Windows should be impact
stages, high use of recirculated air will minimize facility costs.
resistant glass or acrylic, fully glazed. Windows should be
The required quantity of makeup air is determined based on
included if there is a public relations requirement for the
factors such as human occupancy requirements, expected
general public to view the operations. Speaking diaphragms or
solvent and chemical usage, and air pressure requirements.
intercom systems are recommended near all windows to
Recirculated air should be returned prior to the intermediate
facilitate communication with workers inside the cleanroom.
filters for maximum HEPA filter life and minimal shutdown
7.4.6 Closed circuit television systems may be used to
time for filter servicing.
provide views of many areas within the cleanroom and can be
7.6.3 Filtration—The filtration system for a cleanroom typi-
connected to intranet and internet systems for viewing on
cally consists of three or more stages of filters: a rough filter,
computer screens.
one or more layers of intermediate or medium duty filters, and
a final HEPAor ULPAfilter.Ascreen should be included at the
7.5 Location of Cleanrooms—The location of a cleanroom
makeup inlet to keep out pests and large debris. The filtration
within a facility may seriously impact its performance. Con-
system for a controlled area is the same, except that the HEPA
siderable planning is required to have all support equipment
filterstagemaybeomitted.Chemicalandmolecularadsorption
and services in optimum locations for ease of maintenance as
filters should be considered when outside air contains unac-
well as minimizing contaminant generation within or ingestion
ceptable levels of molecular contaminants.
into the cleanroom. Equipment added later, outside a clean-
room may degrade the performance of the cleanroom. All 7.6.3.1 HEPA Filter Specification—High Efficiency Particu-
operations adjacent to the cleanroom should be evaluated for late Air (HEPA) filters must be 99.97 % efficient at removing
the following concerns: 0.3 µm and larger particles in accordance with Type C of
E2217 − 12 (2019)
IEST-RP-CC001. HEPAfilters will provide air at less than ISO are selective; therefore, the selection should be based on the
Class 5 (FS209E Class 100) if in good condition and installed quantities and types of chemicals to be adsorbed and usable
properly. In many cases, HEPA filters will approach the operational life before replacement or reactivation. Molecular
performance of ULPA filters but have not been certified to the adsorbers should be located upstream of the HEPA or ULPA
higher performance. filters because particles may be generated by the adsorber filter
media. Instrumentation and procedures are required to deter-
7.6.3.2 ULPA filters may be used in place of HEPA filters
mine when filters require replacement.
when air cleaner than that certified for HEPAfilters is required.
7.6.4 Ducts—Ducts must be sealed to prevent air leaks and
7.6.3.3 Construction of final filters should be in accordance
ingestion of outside air into the clean air supply and recircu-
with IEST-RP-CC001, type F, construction grade 1 (fire-
latedairreturn.Ductsectionsshouldideallybedeliveredtothe
resistant), with the following exceptions:
job site pre-cleaned and with the ends capped. Duct openings
(1) Cadmium-plated cold-rolled steel sheet, galvanized
should be protected during construction to prevent contamina-
steel sheet, and wood particle board are not recommended as
tion of the interior surfaces.All air ducts and plenums must be
frame materials for aerospace applications. Aluminum or
designed to withstand the pressures imposed by the HVAC
stainless steel frames are recommended.
system and outside vibration sources. Duct interior materials
(2) Acetic acid curing silicone sealants are not recom-
must be smooth, non-shedding, moisture resistant and non-
mendedastheyproduceby-productsthatmaybedetrimentalto
outgassing. The preferred duct material is anodized aluminum.
some aerospace hardware. Low outgassing (controlled volatil-
Insulation material and organic compounds should not be
ity) silicone sealants are recommended.
inside the duct. These materials either collect organic matter
(3) Dioctyl phthalate (DOP) or other volatile aerosols
from the air or contain organic matter that breed molds,
should not be used at any time during the construction and
bacteria, and viruses that can harm personnel and products.
testing of aerospace cleanroom filters. DOP has been found to
evaporateandmigratethroughthefiltersovertime,resultingin 7.6.5 Final Filter Location—HEPA filters may be installed
film contamination of optics and other sensitive surfaces. This in a facility either inside a distribution plenum or at the inlet to
exclusion must be specified on the filter purchase order since it the cleanroom. Only one type of location should be used in a
is often standard practice. It is recommended that the filter be single cleanroom.An exception is the use of local HEPAfilters
tested in accordance with IEST-RP-CC007 for penetration at to provide air to a clean zone, within the cleanroom, that has
special requirements.
rated airflow and leakage using an approved solid aerosol
challenge. Leaks at the filter media or frame should be repaired
7.6.5.1 Plenum Supply with Diffusers—HEPA filters are
at the factory. Excessive leaks at the filter face should be cause
commonly installed inside a distribution plenum outside the
for rejection. The recommendations for ordering, testing,
cleanroom and with diffuser type registers used at the point of
marking, and shipping of HEPAfilters are found in SectionA3
entry to the room. This design is used in many large clean-
of Appendix A of IEST-RP-CC001.
rooms and nonunidirectional airflow cleanrooms.All ductwork
7.6.3.4 Pre-Filters—Pre-filters are selected, sized, and in- downstr
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