Page:NIOSH Manual of Analytical Methods - 7506.pdf/2

 BORON CARBIDE: METHOD 7506, Issue 2, dated 15 August 1994 - Page 2 of 7 REAGENTS: 1.

2. 3.

EQUIPMENT:

Boron carbide, ACS grade, <10-µm particle size. a. Wet-sieve ultrasonically with a 10-µm sieve to approximate respirable dust. Evaporate the alcohol. Dry the sieved material in an oven at 110 °C for 1 h, cool, and store in a desiccator. 2-Propanol. Desiccant.

1. Sampler: a. Filter: 37-mm diameter, 5.0-µm pore size, polyvinyl chloride filter supported with backup pad in a two-piece, 37-mm cassette filter holder (preferrably, conductive) held together by tape or cellulose shrink band. NOTE: Test PVC filter for THF digestion (see Step 4). b. Cyclone: 10-mm nylon, Higgins-Dewell (HD), or equivalent. c. Sampling head holder: Holder must keep the cassette, cyclone and coupler together rigidly so that air enters only at the cyclone inlet. 2. Bulk sampler: PVC membrane filter, 37-mm, 5-µm pore size in two-piece filter cassette. Sample closed face at 4 L/min. 3. Sampling pumps: HD cyclone, 2.2 L/min; nylon cyclone, 1.7 L/min; and bulk sampler, 3 L/min. 4. Silver membrane filters, 25-mm diameter, 0.45-µm pore size. Filters commercially available (e.g., Poretics Corp., Millipore Corp.) 5. X-ray powder diffractometer equipped with copper target X-ray tube, graphite monochromator and scintillation detector. 6. Reference specimen (mica, Arkansas stone or other stable standard) for data normalization. 7. Filtration apparatus and side-arm vacuum flask with 25- and 37-mm filter holders. 8. Sieve, 10-µm pore size, for wet sieving. 9. Analytical balance (0.01 mg). 10. Magnetic stirrer with thermally-insulated top. 11. Ultrasonic bath or probe. 12. Pipets, 2- to 20-mL. 13. Flask, volumetric, 1-L. 14. Desiccator. 15. Bottles, 1-L, with ground glass stoppers. 16. Drying oven. 17. Polyethylene wash bottle. 18. Beakers, borosilicate, 50-mL, and matching watchglasses. 19. Glue or tape for securing Ag filters to XRD sample holder.

SPECIAL PRECAUTIONS: None.

NIOSH Manual of Analytical Methods (NMAM), Fourth Edition, 8/15/94