Asbestos removal evaluation lab report, schools

NYC 9/11 Public Portal Document a Si5efés ‘flee- 8 for ig an pet is both yone gand 538 3 and it and on of Spen- e the ticles mea- # (30) ticle- on APPENDIX 4 143 free water to make $0 milliliters and filtered through a 0.22 pm pore size mixed cellulose ester filter or a 0.2 pm polycarbonate filter backed by an 0.45 pm pore size cellulose ester filter. If by visual observation, the initial beaker contains large non-asbestos fibers (carpet material), dhe entire suspen- sion is passed through a coarse stainless steel mesh screen. The Alters are dried and prepared for TEM analysis according to the NIOSH 7402 prepara- tion procedure ( ester filter)’ or the Yamate, et al. procedure (polycarbonate filter).” At teast two TEM grids from different areas of the filter are prepared for each sample. Alter the duree filtrations are completed, the remaining suspension is transferred to a graduated cylinder and the volume recorded. This volume is added to the volumes of the measured aliquots to obtain the total volume of the sample. This accounts for the variable amount of water absorbed in the carpet during processing. A sample blank is prepared in an identical way as the sample, although no Carpet segment Is actually used in the ultrasonic procedure. THE MICROVAC TECHNIQUE Samptes which are collected by microvacuuming are commonly referred to as microvac samples or microvac dust samples. They are collected by vacuuming a 100 cm? area (or other known area) of carpet with a membrane fitter alr-sampling cassette and vacuum pump. The sampling assembly consists of a 25-mm diameter mixed cellulose ester filter contained in a standard AHERA® air cassette with a one (1) inch piece of tubing attached to the face cap as a nozzte.’ The end of the nozzic is cut at 45 degrees. The cassette is connected to a personal sampling pump with flexible tubing, The pump and cassette assembly are calibrated to 2 Lénin. The 100-cm? area is vacuumed by moving the filter cassette nozzle across the carpet to agitate the carpet pile. The carpet is vacuumed for approxi- mately 30 seconds In ane direction, then another 30 seconds in a direction 90 degrees to the first. After one minute of vacuuming, the pump is turned off and the filter cassette nozzle is plugged and the cassetie is labeled. In the laboratory, the unopened microvacuuming cassettes are wet-wiped and then prepared for analysis under clean room conditions. The cassettes and Glters are rinsed out with particle-free water and refiltered through a second filter which is used in the analysis. The original filter is washed during the sample preparation procedure but olherwise is not used in the preparation. Specifically, the plug from the nozzie of the cassette is removed and the cassette is filled with approximately 10 ml of prefiltered water. The plug is replaced and the cassette is shaken vigorously by hand for two to direc NYC-WTC_000144620