Document wq62BGNa9m3yQgpGeoOy6058Q

TO: Dr. 0. E. Kurt FROM: E. W. Brignac DATE: November 15, 1946 SUBJECT: TS 46-42V, Respirator Filter Tests at Schuylkill Products Company Tests on two MSA "ccmfo-metal" respirator filter units to determine their efficiency in removing lead fumes from the atmosphere gave about 95$ removal of lead from air to give an average exit air analysis of 0.004 mg./cu.ft. or less over a period equivalent to four days breathing time. This is within the allowable limits of lead concentration for inorganic lead. The test method consisted of drawing air through the filter which was sealed into a funnel. The funnel was connected to two iodine scrubbers in series followed by a meter to measure the air flow. A standard air sampler was connected in parallel to determine the lead content of the ambient atmosphere. Poor' agreement was obtained between the ambient air analysis and the total lead collected in the filter units and train, probably because of varying effect of air currents on the quantity of dust collected by the two types of collection openings. The ambient air was collected through a small glass tube and the filter air w&s collected through a comparatively large area opening. Consequently, only results of analyses obtained on the filter train are used ;ln the determination of filter efficiency. The first unit was tested at a height of approximately eight feet above ground level in an area of dense fumes near the Schuylkill Products'Company lead smelter. The second unit was tested at a height of approximately 5-1/2 feet above ground level at the same location. Results of the two test3 are summarized in the attached table. During the first test, lasting approximately 120 hours, 1,461 cu.ft. of air was drawn through the filter and 52*4 mg. of lead was retained on the filter, or an average of 0.0359 mg./cu.ft. was collected. The total lead collected.in the iodine scrubbers and on the filter averaged 0.0375 mg./cU.ft. to give a lead removal efficiency of 94$ for the filter. The lead concentration in the air leaving the filter remained at less than 0.002 mg./cu.ft. throughout the test period equivalent to over four days breathing time. The initial concentration of dust in air leaving the filter was larger than the concentration at the end of the test indicating an increase in filter efficiency as a dust layer builds up on the filter. 68A *, / N9577 Sr. 0 E. Surt -2 lovember 15, 1946 During the second test, lasting approximately 190 hours, 2?2p2 cu.ft. of air was drawn through the filter and 206.7 mg. of lead was retained on the filter, cr an average of 0.0917 mg./ cu.ft. was collected. The total lead collected in the iodine scrubbers and on the filter averaged 0.095*3 mg./cu.ft. to give a lead removal efficiency of 6$ for the filter. The lead concentration in the air leaving the filter remained at less than 0.002 mg./cu.ft.'during the initial period equivalent to 4 days breathing time, with the exception.of one 0.4-day period in which abnormally high analyses were obtained on both the ambient air and filtered air streams. These results- cannot be explained from he information available The increased efficiency with time cf use noted in the first test filter was not obtained wi th the second,. Rather a decrease in efficiency was observed wi th an increase in lead concentration to 0.007 mg*/ cu.ft. at the e>ad of the' test. This is probably due to differences in filter units Pressure drop measurements taken during the second test sho';?ed fan Insignificant increase in pressure drop through the fil ier unit {less than 0.05 Inches of water) during ths test -period These tests Indicate the filter units provide adequate protection against lead dust5 however, additional tests should be made to determine the variation that might exist between filter units. Notebook References iC60. E\<B/mew E. W. Brignac 0007869 f RESPIRATOR FILTER TEST RESULTS Sample Date Tq ZUt T" 1 8/28 2 8/29 3 S/30 4 9/4 5 9/5 Total or Avg. Lead Content of Air Lead Content of Air at Sample Point __ After Filter Sample Mg. Pb Mg. Pb Sample Mg. Pb "MgTTb dumulative Volume in per Volume in per Days of cu. ft. Scrubber cu. ft. cu. ft. Scrubber cu.ft. Breaking Test Wo . 1 102 154 66.0 12.8* 14,2* 0.154 1,500 2.500 0.792 856 0.0015 .0097 .0379 .0621 ... .0603 224 107 375 4l8 .121 0.388 .134 .446 .032 .064 0.0017 .0013 .0012 ,00008 .00019 0.6 .9 2.0 3/2 4.2 349.0 5.802 0.0343 1,461 1.064 0.0009 4.2 *> 9/25 2 9/26 3 10/1 4 10/2 . 5 10/3 6 10/7 7 10/8 8 10/9 Total or Avg. Test Ho . 2 156 37.1 -- 141 98.7 91.2 111.6 II8.5 1.840 6.410 0.780 .034 .620 2.466 1.070 0.0118 381 .1727** 13(5 .0055 ,0004 ,0068 ,0221 ,0090 33-5 275 262 285 311 287 754.1 13.220 0,0326 2.,252 0.280 2.686 0.600 .312 .367 1.244 1.710 2.040 9.239 0.0007 1.1 .0197** 1.5 .0019 2.4 .0011 3.2 ,0014 39 .0043 4.7 ,0054 5.6 ,007.1 6.4 0.00p2 6 .4 '^Vacuum cut off before end of run* The resulting small sample size makes results unreliable. **Abnormal results which cannot be explained from the data obtained. ***Air meter not working. t\ & 0 u 0 7 870 N9577.01