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Performance Evaluation of DM and DFM Filter Respirators—WORKING DRAFT 9.15.92

below 10% leakage.[1] For the 6 DFM filters also tested at 42.5 L/min/filter, they reported leakages of 13%, 12%, 10%, 8%, 7%, and 4%.[2]
  In 1972, Hyatt et al. at LASL published the results of using a 0.82 um MMD (GSD of 1.6) NaCl aerosol to test DM and DFM filters that were approved at that time by the U.S. Bureau of Mines.[3] For 7 DM filters tested at 32 L/min/filter, they reported average filter leakages of 11.5%, 10.7%, 5.3%, 4.0%, 2.7%, 0.9%, and 0.3% and for 6 DFM filters tested at 32 L/min/filter, they reported leakages of 15.3%, 14.8%, 10.1%, 5.7%, 3.2%, and 1.4%.[4]
  In an April 1973 meeting with NIOSH, the Los Alamos Scientific Laboratory (LASL) recommended to the Institute that a small-sized sodium chloride aerosol be used for the Institute's certification testing of DM and DFM filters.’*' Last, recommended that the amount of Permissible DM- and DFM-filter leakage be mar- kedly reduced to the range of 1% to 5%. The LASL, report stated that since before 1970 British respirator standards have required that filter testing be performed with 4 test aerosol of about 0.15 to 0.20 um count median diameter. !&,/63,164

& proposed respirator selection (protection factor) guide that was “distributed to ap- propriate agencies and manufacturers for comments.” They stated that “The first (LASL] selection guide (Table XVI) received many comments, and from these Table XVII was prepared.” In addition to a column containing (assigned) protection factors



“Hyatt E.C., ot al.: Respiratory Studies for. the Nationai Institute for Occupational Safety and Health—July 1, 1972 through June 3, 1973, Loa Alamos Scientific Laboratory, Progress Report, No. LA-5620-PR (May 1974), p. 19,

’“British Standard BS 4558: Positive Pressure, Powered Respirators, British Standards House, Landon (1970),

hyatt E. C. et all: Respiratory Studies for the National Institute for Occupational Safety and Health—July 1, 1972 through June 3, 1973, Los Alamos Scientific Laboratory, Progress Report, No.

LA-5620-PR (May 1974), p. 38.

  1. ↑ Ibid., Table II, p. 794.
  2. ↑ Ibid.
  3. ↑ Hyatt E. C. et al.: Respirator R and D Related to Quality Control; LASL Project P-37, Loa Alamos Scientific Laboratory, Quarterly Report July 1 thru September 30, 1971, No. LA~4908-PR (March 1972).
  4. ↑ Ibid., Table II.
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