MEASUREMENT SYSTEM INCH-POUND MSFC-STD-246 National Aeronautics and REVISION E Space Administration EFFECTIVE DATE: AUGUST 12, 2019 George C. Marshall Space Flight Center Marshall Space Flight Center, Alabama 35812 EM22 MSFC TECHNICAL STANDARD STANDARD DESIGN AND OPERATIONAL CRITERIA FOR CONTROLLED ENVIRONMENTAL AREAS Approved for Public Release; Distribution is Unlimited CHECK THE MASTER LIST— VERIFY THAT THIS IS THE CORRECT VERSION BEFORE USE MSFC Technical Standard EM22 Standard Design and Operational Document No.: MSFC-STD-246 Revision: E Criteria for Controlled Effective Date: August 12, 2019 Page 2 of 91 Environmental Areas DOCUMENT HISTORY LOG Status (Baseline/ Revision/ Document Effective Canceled) Revision Date Description Baseline Baseline 07/29/1966 Baseline release Revision A 04/06/1967 Update reflecting changes to FED-STD-209a. Revision B 07/31/1992 Complete rewrite. Replaces Revision A entirely. Revision C 02/11/2005 Changes made to incorporate new document requirements, reorganization changes, and add information concerning clean work areas. Revision D 03/01/2011 Complete revision. Changes clean area designations to ISO-14644-1 nomenclature, other changes consistent with current industry consensus standards and practices for aerospace cleanrooms and controlled clean facilities. Revision E 08/12/2019 Change identification of responsible organization from EM50 to Materials Test, Chemistry and Contamination Control Branch. Add recommended methods for surface particulate measurement/monitoring. Include “Idle Cleanroom” definition/status/monitoring. Correct misidentified cleanroom filter designation. Revise sampling locations for particle counts. Delete references to retired standards. CHECK THE MASTER LIST – VERIFY THAT THIS IS THE CORRECT VERSION BEFORE USE MSFC Technical Standard EM22 Standard Design and Operational Document No.: MSFC-STD-246 Revision: E Criteria for Controlled Effective Date: August 12, 2019 Page 3 of 91 Environmental Areas FOREWORD The purpose of this Standard is to present data and information that relate to contamination control of MSFC environmentally controlled areas, cleanrooms, flow benches, and unidirectional clean air devices. It specifies environmental control operating standards to be used as minimum criteria for rooms and hardware requiring environmental control. This Standard provides guidelines for selecting the environmental facilities and operating conditions necessary for contamination control of critical aerospace hardware, and associated test hardware, facilities, Ground Support Equipment (GSE), and related components for MSFC-managed projects/programs during MSFC operations; it also lists quality control measures to ensure compliance. CHECK THE MASTER LIST – VERIFY THAT THIS IS THE CORRECT VERSION BEFORE USE MSFC Technical Standard EM22 Standard Design and Operational Document No.: MSFC-STD-246 Revision: E Criteria for Controlled Effective Date: August 12, 2019 Page 4 of 91 Environmental Areas TABLE OF CONTENTS PARAGRAPH PAGE DOCUMENT HISTORY LOG ................................................................................................... 2 FOREWORD................................................................................................................................. 3 TABLE OF CONTENTS ............................................................................................................. 4 1. SCOPE ............................................................................................................................... 6 1.1 Scope. .................................................................................................................................. 6 1.2 Authority. ............................................................................................................................ 6 1.3 Responsibility. .................................................................................................................... 6 1.4 Specification on Contracts. ................................................................................................. 7 2. APPLICABLE DOCUMENTS ........................................................................................ 7 2.1 Applicable Documents. ....................................................................................................... 7 2.2 Reference Documents. ........................................................................................................ 8 3. DEFINITIONS ................................................................................................................ 10 3.1 Acronyms used in this standard. ....................................................................................... 10 3.2 Glossary of Terms. ............................................................................................................ 12 4. GENERAL REQUIREMENTS ..................................................................................... 15 4.1 Facility Classification and Identification. ......................................................................... 15 4.2 Determination of Required Environmental Controls. ....................................................... 17 4.3 Facility Operating Procedure. ........................................................................................... 18 4.4 General Operating Practices. ............................................................................................ 20 5.0 DETAILED REQUIREMENTS .................................................................................... 29 5.1 Common Design and Construction Criteria for Clean Facilities. ..................................... 29 5.2 Continuous Operation of Air Systems. ............................................................................. 33 5.3 Controlled Areas Class 8.5. .............................................................................................. 33 5.4 Clean Work Areas Class 8. ............................................................................................... 35 5.5 Conventional Flow Cleanrooms. ...................................................................................... 37 5.6 Unidirectional Flow Cleanrooms. ..................................................................................... 47 5.7 Unidirectional Flow Bench/Clean Work Station. ............................................................. 53 CHECK THE MASTER LIST – VERIFY THAT THIS IS THE CORRECT VERSION BEFORE USE MSFC Technical Standard EM22 Standard Design and Operational Document No.: MSFC-STD-246 Revision: E Criteria for Controlled Effective Date: August 12, 2019 Page 5 of 91 Environmental Areas 5.8 Clean Tents and Other Unidirectional Flow Clean Air Devices. ...................................... 61 5.9 Certification and Monitoring Practices. ............................................................................ 65 6.0 NOTES ............................................................................................................................. 72 6.1 Contamination Control...................................................................................................... 72 6.2 Establishment of Hardware Cleanliness Requirements. ................................................... 77 APPENDICIES A. Particulate Sampling In Cleanrooms And Other Controlled Clean Areas ........................ 79 B. Monitoring Of Cleanroom Garments ................................................................................ 84 C. Flow Bench General Operating Procedures ...................................................................... 88 TABLES I. Environmental Standards for Clean Facilities .................................................................. 89 FIGURES 1. Conventional Flow Cleanroom Air Patterns ..................................................................... 38 2. Conventional Flow Cleanroom Layout ............................................................................. 39 3. Unidirectional Flow Cleanroom Air Patterns ................................................................... 48 4. Unidirectional Cross-Flow Cleanroom ............................................................................. 49 5. Unidirectional Down-Flow Cleanroom ............................................................................ 49 6. Horizontal Flow Bench ..................................................................................................... 54 7. Vertical Flow Bench (non-recirculating) .......................................................................... 55 8. Down-flow Clean Tent ..................................................................................................... 63 9. Unidirectional Flow Clean Tunnel.................................................................................... 64 10. Particulate Fallout vs. Time for Cleanrooms* .................................................................. 73 11. Cleanroom Sampling Plan ................................................................................................ 82 12. Cleanroom Garment Sampling Locations ......................................................................... 85 CHECK THE MASTER LIST – VERIFY THAT THIS IS THE CORRECT VERSION BEFORE USE MSFC Technical Standard EM22 Standard Design and Operational Document No.: MSFC-STD-246 Revision: E Criteria for Controlled Effective Date: August 12, 2019 Page 6 of 91 Environmental Areas 1. SCOPE 1.1 Scope. This document establishes Marshall