Document zzygjNBEkkx5dr7QGE97GBw0g

E. I. du Pont dc Nemours & Company Wilmington, Delaware imm CC: J.A. Sigaan-Tsxtile Fibers-Wila, J.A. Collins-M.L. Honack J.R. Allen CNOINCCelNa OCPARTMCMT January 5, 1971 R. B. HATDEN teithe fibers department NEMOURS BUIIDINQ, WILMINGTON INDUSTRIAL DEPARTMENTS MATERIALS ENGINEERING THERMAL INSULATION RELATIVE DUSTINESS STUD! Attached isji copy of a study report by Haskell Lab. on the dustiness of thermal insulation materials. This study was initiated by the Materials Engineering.Group of ESD and was done in conjunction with Haskell Lab. and the Engineering Test Center as a part of the Company Thermal Insulation Program. The purposeof the study was to determine the relative potential dustiness, as received from the manufacturer, of the asbestos bearing thermal insulations presently in our engineering standards. With the information contained in this report and the following information in this letter, it should be possible to select insulations, when bandied with reasonable care, that will fall within the presently established Threshold Limit Values (TLV) for asbestos dust. Conversely it points out the brands of insulation that present the greatest potential hasard. I recommend that the fiber count be used to determine the least hazardous material rather than the materials with higher coarse/ fine ratios (irrespirable/respirable) since the fiber counts are made on what are essentially respirable samples. Note that the count of fibers greater than 5 microns in length represents only an Id minute sampling period. The Threshold Limit Values (TLV) established by the American Conference of Governmental Industrial Hygienists represent time-weighted concentrations for a 7 or 8-hour work day and 40-hour work CTree thino* roe CTree uvino . . rweouaw cHKMisrmr DUP 0973632 2 January 5 1971 R. B. Hayden weak. An insulator working under noraal insulation shop conditions would be exposed to much less average concen trations. The ACGIH states "Time-weighted averages permit excursions above the' limit provided they are compensated by equivalent excursions below the limit during the work day". The statement in the report that the composition of the samples taken during sawing were the same as the samples taken after a settling period is significant in that we should not favor materials that visibly appear to have rapid settle out of dust after working them. An inquiry to all of the manufacturers of the materials we tested determined that the types of asbestos in the insulations was either amosite or chrysotile; none con tained any crocidolite, which is considered to be the least desirable. The percent of asbestos content of each of the insulations, as advised by the manufacturers compared very closely to the amounts determined in our study. Specific recommendations have not been made because the insulations showing the least fiber count can be handled so carelessly that they can become the most hazardous, and conversely the ones showing the higher fiber counts can be handled so carefully that they become the least hazardous. Since Insulation shops and operations vary widely throughout the Company the insulation selection should be made to meet the specific site conditions. If I can be of further service to you, please contact me. ENGINEERING SERVICE DIVISION GEL/cgs Attach. 0UP 0973633