Airborne Particulate Cleanliness Class Comparison

 Airborne Particulate Cleanliness Classes

 Required Testing

 Optional Testing

  ISO Cleanroom Standards 

  ISO TC 209 Working Groups

Introduction

Federal Standard 209E has long been the only definition of cleanroom classification levels available from a standards organization. FS209E, Airborne Particulate Cleanliness Classes in Clean Rooms and Clean Zones, is from the U.S. General Service Administration and approved for use by all U.S. agencies. In the absence of an international standard, FS 209E was broadly used internationally.

The need for a new international standard that covered more cleanroom environmental parameters and practices led to the formation of a technical committee of the International Standards Organization. The technical committee is named, ironically, TC 209 Cleanrooms and Associated Controlled Environments. The goal of TC 209 is "standardization of equipment, facilities, and operational methods for cleanrooms and associated controlled environments. This includes procedural limits, operational limits and testing procedures to achieve desired attributes to minimize micro contamination."

This ISO committee will produce 10 new standards documents that relate to cleanrooms or clean zones (described below). The first two standards have been published: ISO 14644-1 and -2. The first document, ISO 14644-1, Cleanrooms and associated controlled environments Part 1: Classification of airborne particulates has been released as a final draft international standard (FDIS). The second document, ISO 14644-2, Cleanrooms and associated controlled environments Part 2: Testing and monitoring to prove continued compliance with ISO 14644-1; has been released as a draft international standard (DIS). Both are legal for use in trade.

By U.S. law, FS 209E can be superseded by new international standards. It is expected that 209E will be in use in some industries through the next five years, but that eventually it will be replaced globally by ISO 14644-1.

The actual text of the standards must be ordered from the appropriate standards organization (see Sources and Links). This paper gives a general overview of the required particle count measurements given in the standards.

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Summary of FS 209E and ISO 14644-1 and -2

The cleanliness classification levels defined by FS209E and ISO 14644-1 are approximately equal, except the new ISO standard uses new class designations, a metric measure of air volume and adds three additional classes - two cleaner than Class 10 and one beyond than Class 100,000. The second new ISO standard, ISO 14644-2, gives requirements for monitoring a cleanroom or clean zone to provide evidence of its continued compliance with ISO 14644-1.

The following table compares FED STD 209E to the new ISO 14644-1 classifications.

Airborne Particulate Cleanliness Class Comparison

The ISO standard also requires fewer sample locations, especially as the cleanroom/area size increases; however, the ISO standard does require minimum one minute samples, whereas the Federal Standard allows shorter samples, especially at smaller particle sizes.

For example, to certify an FS Class 10 cleanroom (ISO class 4), with 250 square feet (7.08 square meters), classified at 0.3 micron with a 1 cf/m flow rate particle counter, the required number of sample locations, sample volumes, and sample times would be as follows:

FS209E requires 10 sample locations, 19.6 liter minimum sample volume (0.85 cf), and a sample time of 51 seconds. This yields a total minimum sample time of 510 seconds and 10 equipment moves.

 ISO 14644-1 requires 5 sample locations, 19.6 liter minimum sample volume (0.85 cf ), but also a minimum sample time of one minute yielding three samples of one cubic foot. This yields a total sample time of 180 seconds and three equipment moves.

The precise count levels required by ISO 14644-1 for each classification, by particle size, are given below.

Airborne Particulate Cleanliness Classes (by cubic meter)

ISO 14644-2 determines the type and frequency of testing required to conform with the standard. The following tables indicate which tests are mandatory and which tests are optional.

Required Testing (ISO 14644-2)

Optional Testing (ISO 14644-2)

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The History and Future of ISO Cleanroom Standards

In 1992, at the urging of the Institute of Environmental Sciences, the American National Standards Institute petitioned ISO to create a technical committee on cleanrooms and associated controlled environments. This new committee, ISO TC 209, was formally established in May 1993. Its mission is to develop an international standard for cleanrooms and associated controlled environments that encompasses the standardization of equipment, facilities, and operational methods, while also defining procedural and operational limits and testing procedures to minimize contamination.

Thirty-four countries are currently active in ISO TC 209. Voting members are Australia, Belgium, China, Denmark, Finland, France, Germany, Italy, Jamaica, Japan, Korea, The Netherlands, Norway, Portugal, Russia, Sweden, Switzerland, the United Kingdom, and the United States. Nonvoting members are Bulgaria, the Czech Republic, Egypt, India, Ireland, Malaysia, New Zealand, the Philippines, Poland, Saudi Arabia, South Africa, Thailand, Turkey, Ukraine, and Yugoslavia.

Two Draft International Standards (DIS) have been released by the committee: ISO/DIS 14644-1, Cleanrooms and associated controlled environments-Part 1: Classification of airborne particulates, and ISO/DIS 14644-2 Cleanrooms and associated controlled environments-Part 2: Specifications for testing and monitoring to prove continued compliance with ISO 14644-1. These first ISO cleanroom standards are two of 10 documents (see table A) that will make up the new family of global cleanroom standards. Many of these documents are at the final voting stage and can be legally used in trade.

ISO Cleanroom Standards 

ISO/FDIS 14644-1 Classification of Air Cleanliness
This document covers the classification of air cleanliness in cleanrooms and associated controlled environments. Classification in accordance with this standard is specified and accomplished exclusively in terms of concentration of airborne particles.

ISO/DIS 14644-2 Cleanroom Testing for Compliance
This document specifies requirements for periodic testing of a cleanroom or clean zone to prove its continued compliance with ISO 14644-1 for the designated classification of airborne particulate cleanliness. These requirements invoke the test described in ISO 14644-1 for the classification of the cleanroom or clean zone. Additional tests are also specified, to be carried out based on the requirements of this International Standard. Optional tests, to be applied at the user's discretion, are also identified.

ISO-14644-3 Methods for Evaluating & Measuring Cleanrooms & Associated Controlled Environments

This document describes the necessary performance tests for various types of cleanrooms. The occupancy states of "as built", "at rest", and "in operation" are defined as well as appropriate levels of certification. A large index is provided on a variety of test methods and appropriate equipment.

ISO-14644-4 Cleanroom Design & Construction

This document will be a primer on the design and construction of cleanrooms. It will cover all aspects of the process from design development to startup and commissioning.

ISO-14644-5 Cleanroom Operations

This document will be a primer on cleanroom operation. It will cover all aspects of the operation of a cleanroom including entry and exit procedures for equipment and personnel, education and training, cleanroom apparel, and facility issues such as maintenance, housekeeping, monitoring, system failure, etc.

ISO-14644-6 Terms, Definitions & Units

This document will provide a consistent reference for all terms, definitions and units discussed across all ISO cleanroom standards.

ISO-14644-7 Enhanced Clean Devices

This document will focus on specialized stand-alone clean spaces including their design, construction, and operations.

ISO-14644-8 Molecular Contamination

This will be a new document covering measurement of airborne molecular contamination in clean zones. The first meeting is scheduled for December 1998.

ISO-14698-1 Biocontamination: Control General Principles

This document describes principles and basic methodology for a formal system to assess and control biocontamination where cleanroom technology is applied.

ISO-14698-2 Biocontamination: Evaluation & Interpretation of Data

This document describes basic principles and methodology for microbiological data evaluation. It provides a method of estimating of biocontamination from sampling for viable particles in zones at risk.

ISO-14698-3 Biocontamination: Methodology for Measuring Efficiency of Cleaning Inert Surfaces

This document outlines the methodology to measure the effectiveness of cleaning and/or disinfection of inert surfaces having biocontaminated wet soiling or biofilms. 

ISO TC 209 Working Groups

Listed below are ISO TC 209's seven working groups and their missions.

Working Group 1

ISO 14644-1, "Classification of Air Cleanliness" Three new classes have been added to the existing standard, Federal Standard 209, two cleaner and one dirtier.

ISO 14644-2 covers specifications for testing and monitoring. This document specifies the requirements for monitoring a cleanroom or clean zone to provide evidence of its continued compliance with ISO 14644-1 for the designated classification of airborne particulate cleanliness. A schedule of normative and informative tests is included in the document.

Working Group 2

ISO 14698-1, "Biocontamination Control General Principles". This document describes the principles and basic methodology for a formal system to assess and control biocontamination. It will include the general requirements of a sampling plan; target, alert, and action levels; qualification; and reporting.

ISO 14698-2, "Evaluation and Interpretation of Biocontamination Data." This document describes the basic principles and methodological requirements for all microbiological data evaluation and the estimation of biocontamination data obtained from sampling for viable particles. It will also include evaluation of the initial monitoring plan and of the data resulting from routine monitoring, as well as analysis of the data, trending, and record keeping.

Working Group 3

A working group on metrology and testing methods. Performance tests are specified at operational phases—as-built, at-rest, and operational. The items to be measured are categorized as either primary or user-optional tests. Primary tests include particle count, airflow velocity, airflow volume, pressure differential, and installed filter leakage. User-optional tests include flow visualization, airflow parallelism, airflow turbulence, temperature, humidity, molecule contamination, electrostatic charge, particle fallout, recovery, and integrity.

Working Group 4

ISO 14644-4, "Design and Construction." This document specifies requirements for the design and construction of cleanroom and clean air devices, as well as requirements for start-up and qualification. It also provides guidance on the basic elements of design and construction.

Working Group 5

A cleanroom operations working group. Topics to be addressed include entry/admittance, procedures, and cleaning, as well as maintenance as it relates to equipment, materials, and people.

Working Group 6

In detailing terms, definitions, and units, the definitive document of this working group must include all definitions from all approved documents of ISO TC 209. Consequently, it will be the final ISO TC 209 document.

Working Group 7

The Enhanced Clean Devices working group.

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Sources and Links

Institute of Environmental Sciences & Technology (IEST)
Arlington Place One
2340 South Arlington Heights, Suite 100
Arlington Heights, IL 60059
Phone: 1-847-981-0100
Fax: 1-847-981-4130

Standards Order Desk
Naval Publications and Forms Center
700 Robbins Ave., Section D BLD4
Philadelphia, PA. 19111
Phone: 215-697-2667
Fax: 215-697-2978

Summary of ISO Cleanroom Standards, from Midwest Cleanroom Associates

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Document P/N 2084056.  Written by Scott Hjelmervik, Software and Systems Manager, and by Joe Gecsey, Airborne Products Manager . Copyright by Pacific Scientific Instruments Company, January 1999. All Rights Reserved. Specifications subject to change without notice .