Document aD65EJvm5Nzajexxy1pvD5DRy

CertainTeed Corporation P.O. Box 860 Valley Forge, PA 19482 (215) 687-5000 CertainTeed April 21, 1980 Ms. Joan Wronski, Director National Loss Control Service Corporation Environmental Science Laboratory Long Grove, IL 60049 Dear Ms. Wronski: Please analyze the following PVC (FWS-B) filters for percent free silica (Quartz, Cristobalite, Tridymite) by the X-Ray diffraction method. They are as follows: Filter 7# S'.o x Dust Weight A 459 f'l* A 462 \ A 470. A 476* oil OZ3 Dll 07V A 504 ' A 551 * A 546. A 500* A 469 12.7. in. 1>7 7. 11 7. 1.27. <1 7. 2,8 7. 0.133 mg. 0.167 mg. 0.126 mg. 0.149 mg. 0.491 mg. 4.21 mg. 15.7 mg. 9.77 mg. 0.383 mg. BLANK If you have any questions, please feel free to call me. Corporate Industrial Hygienist TCS/ejb Enclosures (10) 125 CTD019197