Cleanroom operators must wear a cleanroom-compatible apparel system (coveralls, hood, boots, and sometimes undergarments) constructed of 100 percent polyester to prevent cleanroom contamination. But when ignited, 100 percent polyester will melt and likely cause injury to the cleanroom operator if exposed to electric arc or flash fire.
Cleanroom FR fabric
Compliance to NFPA 70E in cleanroom environments requires that all personnel working on electrical equipment operating at >50V wear arc-flash protective apparel. Polyester is specifically prohibited under any circumstances when exposed to live electrical parts operating >50V.
Construction of cleanroom FR apparel
Typical cleanroom apparel constructed of cleanroom FR fabric meets NFPA 70E Category 1. Seam construction of cleanroom FR apparel must comply with IEST-RP-CC003.3 (i.e. 100 percent 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, etc.) in the garment must be cleanroom-compatible, gamma-compatible and flame-resistant as well. Flame-resistant cleanroom apparel must meet ASTM F1506 and be labeled as such to meet NFPA 70E.Validating cleanroom FR apparel
Validation of the cleanroom flame-resistant garment system includes results of all tests performed to confirm cleanroom compatibility, gamma compatibility and flame resistance. Testing of cleanroom FR apparel must be performed to validate arc-flash resistance per ASTM F 1959 to determine the arc rating. Sterility of the garment per ANSI/AAMI/ISO 11137-2006 over time must be validated in FDA-regulated industries as well as the durability of flame resistance after many exposures of gamma radiation.
Over the past ten years, a new generation of fabrics constructed of Dupont Nomex® and durable carbon threads, and cleanroom compatible snaps and zippers encased in Nomex® fabric has been developed. These garment systems are cleanroom-compatible, gamma-compatible and flame-resistant. There now are fabrics specifically designed to meet the arc thermal and flame-resistant requirements of cleanroom operations.
Validation of cleanroom arc thermal and flame-resistant apparel begins with the Master Plan. The Master Plan is the overview of the lifecycle of the validation process. A Master Plan outline defines the steps and benchmarks of developing the validation protocol, the installation qualification, operation qualification, performance qualification, and change control.
In all of these phases, Standard Operating Procedures (SOPs) are prepared and serve as the blueprint to perform each of the qualifications. If any part of these results fails to meet the required specifications, a change control process is used to make a change to either the specification or the system.
Once the validation protocol is developed, the SOPs written, and training and responsibility assigned, the validation process is initiated.
Installation qualification (IQ) documents that the arc thermal flame-resistant cleanroom garment compares at minimum equally in fabric, construction, and barrier specifications, if not better than the currently used reusable cleanroom apparel. All supporting data (i.e. tear tensile strength, static decay, surface resistivity, pore size, moisture vapor transition rate) and documented evidence are usually provided by the supplier of the fabric and components and the apparel manufacturer and reviewed during a vendor audit.
Operation qualification (OQ) documents that the arc thermal flame-resistant garment system compares equally during normal processing operations, if not better than the currently used reusable cleanroom apparel. Typical monitoring test results of both viable and non-viable particles of the apparel system (i.e. Helmke Tumble test, Body Box, and Bacterial Filtration Efficiency) should provide the required documented evidence to compare arc thermal flame-resistant apparel to reusable apparel.
Performance qualification documents that the arc thermal flame-resistant apparel system compares equally over an extended period of time, if not better than the currently used reusable apparel. The same monitoring test results of both viable and non-viable particles of the apparel system and the same fabric testing performed initially before the laundering process began (i.e. tear tensile strength, static decay, surface resistivity, pore size, moisture vapor transition rate) as well as gamma compatibility should provide the required documented evidence to prove the arc thermal flame-resistant cleanroom apparel is as robust and reproducible as reusable cleanroom apparel.
During the validation process, changes may be required. Change control is the process for providing documented evidence of any change performed for any reason. Once it is determined that change is required, the change is documented and implemented. After implementation of the change, the changed process must be revalidated.
Once all documentation is accumulated from the installation qualification, operation qualification and performance qualification, a summary report is prepared. This completes the validation process and completes execution of the Master Plan. The summary consists of a summation of the lifecycle that has been outlined in the validation protocol, documentation of the testing and verification of test data. Once data is compiled and verified, statistical analysis is performed on the data and included in the summary report.
Cleanroom-FR compromise
If cleanroom operations require compliance to NFPA 70E Hazard/Risk Category (HRC) 2, a compromise of the two specifications must be weighed (increased contamination of the cleanroom versus protection of cleanroom operators/electricians).
Fabric and garment manufacturers worldwide constantly research the construction of arc thermal flame-resistant cleanroom garments and how to meet the compromises of wearer comfort, cleanroom compatibility, gamma compatibility and flame resistance (both Category 1 and 2) characteristics. New dual-layer systems available now offer cleanroom compatibility and HRC 2 compliance.
