IEST to Update Outdated Mil-Standards
By Lisa A. Coleman
Mount Prospect, IL–At the urging of the U.S. Army`s Redstone Army Missile Command (Hunstville, AL), the Institute of Environmental Sciences will formally review and update Mil-Hdbk-406, -407 and Mil-Std-1246. Both Mil-Hdbk-406 and -407 are now over 20 years old.
Mil-Hdbk-406, Contamination Control Technology, Cleaning Materials, Precleaning for Precision and Use in Cleanrooms and Clean Workstations, and Mil-Hdbk-407, Contamination Control Technology, Precision Cleaning Methods and Procedures, are used primarily in the military, aerospace and related industries. About two years ago, the Institute revised Mil-Std-1246, Product Cleanliness Levels and Contamination Control Program. It will now be transformed from a military-based standard to an ANSI national standard.
According to Bob Mielke, the Institute of Environmental Sciences` technical vice president of contamination control, the review process of the military standards is, “overdue. These documents haven`t been looked at for a considerable period of time,” he says. Mielke has set up an offshoot of the normal standards and practices group–a governmental working group–due to the different procedures the government follows when voting and approving military standards.
The last publication date for Mil-Hdbk-406 was 1971. Says Joyce Steakley, manager of Lockheed Martin Missiles & Space`s material and process control laboratories and organizer of the working groups, “Mil-Hdbk-406 has very detailed information about what each type of solvent is suitable for cleaning, its physical properties and effects on other materials. If you`ve got to clean something, you`d use this document to select the best choice of cleaning materials for a specific application.”
One example of the problems with the current handbook is that it references a host of ozone-depleting and carcinogenic chemicals–benzene, carbon tetrachloride, Freon, etc.–which are no longer used in industry. Likewise, Mil-Hdbk-407, which details the precision cleaning methods using the solvents specified in -406, was last published in 1972. The 300+ page document details cleanroom construction, design, features, environmental conditions, etc. “All of it is in accordance with Fed-Std-209A. And, of course, today we`re up to Fed-Std-209E! So it`s extremely outdated,” says Steakley. The rest of Mil-Hdbk-407 defines, in great detail, cleaning methods and how to control contaminants in gases. In addition, it explains various cleaning methods referencing Mil-Std-1246A–the current revision is Mil-Std-1246C. “It (the standard) has held it`s own for quite a long time, but all that`s going to change with the elimination of many of these solvents,” adds Steakley. “It`s a major updating, which when completed will be a huge source of information. These are really `how-to` documents that give us all the details necessary for implementation.”
One working group will be assigned per standard. An organizational meeting was scheduled for mid-May. n