Compliance to NFPA 70E in cleanroom environments requires that all personnel working on electrical equipment operating at >50V wear arc-flash protective garments to prevent injury. Polyester is specifically prohibited under any circumstances when exposed to live electrical parts operating >50V. The automotive industry has been using cleanroom FR garments meeting ASTM F1506 for workers exposed to electric arc for several years in their cleanrooms and recently all cleanroom industries have begun wearing these cleanroom FR garments in their manufacturing cleanrooms. The 2009 revision of NFPA 70E requires all daily wear FR garments to meet Hazard Risk Category (HRC) 2 or APTV ≥ 8 cal/cm2. The current Nomex® Cleanroom undergarment fabric and coverall, hood, boots, and frock fabrics test at ≤ 5.0 cal/cm2. Therefore, the recommended gowning configuration for compliance to NFPA 70E Hazard Risk Category 2 is:
- ISO Class 3-5 Cleanrooms = Cleanroom FR building suit top and bottom worn under Cleanroom FR coverall, hood, and boots.
- ISO Class 6-8 Cleanrooms = Cleanroom FR building suit top and bottom worn under Cleanroom FR frock.
Dupont’s filament Nomex® is used to create the flame resistant characteristic in fabrics for cleanroom applications. Normal woven Nomex® yarn generates particles in the cleanroom however the filament Nomex® used in cleanroom FR fabrics uses the same Nomex® chemical structure in a filament form to replace the fibrous forms used in most Nomex® fabrics. In most of the FR cleanroom fabrics filament Nomex® and carbon yarn is combined and woven into fabric. This resulting fabric is flame resistant, cleanroom compatible, gamma compatible, and static dissipative. Allocation requirements to military garments and the Department of Defense have created a lower supply for domestic, commercial manufacture of cleanroom FR fabric. Many orders placed today for cleanroom FR garments may not be completed for six months but research and development is ongoing to find other compliant materials for cleanroom applications.
CONSTRUCTION OF CLEANROOM FR GARMENTS
Typical cleanroom garments constructed of cleanroom FR fabric meet NFPA 70E Hazard Risk Category 1 or ATPV ≤ 5.0 cal/cm2. Seam construction of cleanroom FR garments must comply with IEST-RP-CC003.3 (i.e. 100% Nomex® filament thread for sewing, serging of all rough edges and flat feld seams, etc.) to assure cleanroom compatibility, durability of the seams, and encapsulation of particles. All other components (i.e. zippers with protective tape, protective snaps, tunnelized neoprene wrist closures, boot soles, etc.) in the garments must be cleanroom compatible, gamma compatible, and flame resistant as well. Flame resistant cleanroom garments must meet ASTM F1506 and be labeled as such to meet NFPA 70E.
VALIDATION OF CLEANROOM FR GARMENTS
The validation of the cleanroom flame resistant garment system includes all the results of the tests performed to confirm cleanroom compatibility, gamma compatibility, and flame resistance. Testing of cleanroom FR garments must be performed to validate arc-flash resistance per ASTM F1959 to determine the arc rating. The sterility of the garment per ANSI/AAMI/ISO 11137-2006 over time must be validated in the FDA regulated industries as well as the durability of flame resistance after many exposures of gamma radiation.
COMPROMISE OF CLEANROOM PROTOCOL AND FLAME RESISTANT PROTECTION
The 2009 revision of NFPA 70E requires all daily wear to meet Hazard Risk Category (HRC) 2, therefore all cleanroom operators must wear the two layers of cleanroom FR garments as stated above. Proper use of cleanroom FR garments mandates that they are worn correctly and are cleaned and repaired correctly or removed from service.
The gowning protocol requires the cleanroom FR building suit top and bottom to be donned over all natural, non-melting underwear such as silk or cotton and worn under an additional layer of cleanroom FR garments. For compliance in ISO Class 6-8 cleanroom environments, a cleanroom FR frock is donned over the building suit top and bottom using recommended cleanroom gowning protocol. A disposable Nomex® bouffant is worn under a FR balaclava or helmet and shield. FR gloves are donned to protect the hands and fingers. For compliance in ISO Class 3-5 cleanroom environments, a cleanroom FR coverall, hood, and boots are donned over the cleanroom FR building suit top and bottom using recommended cleanroom gowning protocol. A disposable Nomex® bouffant is worn under the cleanroom FR hood. FR gloves and a FR shield are donned to protect hands, fingers, and face. This dual layer cleanroom FR garment system may be heavy and hot, and operators sometimes are uncomfortable wearing these garments for long periods of time in the cleanroom environments. However, constant research and development of the fabrics, components, and construction of these garments and of meeting the compromises of wearer comfort, cleanroom compatibility, gamma compatibility, and flame resistance (both Category 1 and 2) characteristics is being conducted by fabric and garment manufacturers worldwide which offer Cleanroom compatibility and HRC2 compliance per the 2009 revision of NFPA 70E