6. Apparatus (see Fig. 1)
6.1 Porcelain Crucible, wide form, glazed throughout, or a silica crucible; 29- to 31-mL capacity, 46 to 49 mm in rim diameter.
6.2 Iron Crucible - Skidmore iron crucible, flanged and ringed, 65- to 82-mL capacity, 53 to 57 mm inside and 60- to 67-mm outside diameter of flange, 37 to 39 mm in height supplied with a cover without delivery tubes and having the vertical opening closed. The horizontal opening of about 6.5 mm shall be kept clean. The outside diameter of the flat bottom shall be 30 to 32 mm.
6.3 Iron Crucible - Spun sheet-iron crucible with cover; 78 to 82 mm in outside diameter at the top, 58 to 60 mm in height, and approximately 0.8 mm in thickness. Place at the bottom of this crucible, and level before each test, a layer of about 25 mL of dry sand, or enough to bring the Skidmore crucible, with cover on, nearly to the top of the sheet-iron crucible.
6.4 Wire Support - Triangle of bare Nichrome wire of approximately No. 13 B & S gage having an opening small enough to support the bottom of the sheet-iron crucible at the same level as the bottom of the heat-resistant block or hollow sheet-metal box (6.6).
6.5 Hood - Circular sheet-iron hood from 120 to 130 mm in diameter the height of the lower perpendicular side to be from 50 to 53 mm; provided at the top with a chimney 50 to 60 mm in height and 50 to 56 mm in inside diameter, which is attached to the lower part having the perpendicular sides by a cone-shaped member, bringing the total height of the complete hood to 125 to 130 mm. The hood can be made from a single piece of metal, provided it conforms to the foregoing dimensions. As a guide for the height of the flame above the chimney, a bridge made of approximately 3-mm iron or Nichrome wire, and having a height of 50 mm above the top of the chimney, shall be attached.
6.6 Insulator - Heat-resistant block, refractory ring, or hollow sheet-metal box, 150 to 175 mm in diameter if round, or on a side if square, 32 to 38 mm in thickness, provided with a metal-lined, inverted cone-shaped opening through the center; 83 mm in diameter at the bottom, and 89 mm in diameter at the top. In the case of the refractory ring no metal lining is necessary, providing the ring is of hard, heat-resistant material.
NOTE 5 - It is not know what type of insulators were used in the round robin conducted for obtaining the precision given in Section 13.
6.7 Burner, Meker type, having an orifice approximately 24 mm in diameter.
7. Sampling
7.1 For sampling techniques see Practices D 4057 and D 4177.
