Testing results prove new methods for mopping cleanrooms
04/01/2000
Tammy Wright
Mount Prospect, IL—Extensive field testing by industry has led the Institute of Environmental Science and Technology's Working Group on cleanroom housekeeping, operating and monitoring procedures to add two alternate methods of mopping walls and floors to its recommended practice (RP) 18.2.
 |
Dixon: Mop methods adopted.
More than 22 companies representing the semiconductor, wafer manufacturing, disk drive, aerospace, medical device, pharmaceutical and biotech fields answered the IEST's call last year for volunteers to determine the validity of new methods proven acceptable by technical studies (see "Wanted: volunteers to test alternate mopping methods, proven acceptable by technical studies (see "Wanted: volunteers to test alternate mopping methods," CleanRooms, July 1999, p. 6), confirms WG-CC018 Chair Anne Marie Dixon, who is also principal of Cleanroom Management Associates Inc. (Carson City, NV), as well as chairman of the U.S. Technical Advisory Group (TAG) to ISO/Technical Committee 209 and head of the U.S. delegation to ISO/TC 209.
The proposed alternate tests allowed participants to utilize existing tools, cleaning agents and disinfectants, but specified the use of a modified figure eight to mop floors and a horizontal motion for mopping walls. Current recommended methods of cleaning include mopping floors with a pull-lift technique and mopping walls with a top-down technique.
"The effort was tremendous on the part of industry, " says Dixon. "The companies confirmed, with live testing, the results of lab studies performed by the University of Arizona for particle removal and by the Research Triangle Institute for microbial removal, which showed the proposed alternate methods within 98 to 99 percent efficiency of the RP's original mopping methods."
Dixon says each participant - whose identity is being kept confidential - dedicated six to nine months to the study, submitting monthly summaries as well as a compilation report at the end of its research period, which detailed its findings. She believes the field test was an important mission from both an IEST and an ISO perspective because information was obtained from a total cross section of current cleanrooms ranging from ISO Class 3 (Class 1) to ISO Class 8 (Class 100,000).
"In some cases, firms actually performed experiments using multiple cleanrooms of various classes, " Dixon adds. "For example, one company tested the alternate methods in Class 100, 10,000 and 100,000 cleanrooms and collected and analyzed all the data."
Based on these broad results, WG-CC018 has agreed to add the two new mopping methods to its RP as acceptable alternate techniques; the original mopping methods will remain in place. Members have also decided to update the document by including new references and increased supply lists.
Dixon says the committee will review the final draft of the document when it reconvenes at the IEST's annual technical meeting being held April 30-May 4 in Providence, RI.
"I expect the revised document to be available for sale through the IEST no later than the third quarter of this year," she notes.
Editor's note: Ms. Dixon would like to publicly thank participants in this field test for graciously offering their time, manpower and facilities to move research forward and advance the science of surface contamination control.