7. Materials
7.1 Purity of Reagents - Reagent grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all reagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.
7.2 Purity of Water - Reagent water as defined by Type II of Specification D1193.
7.3 Acetone, minimum reagent grade. (Warning - Flammable. Health hazard.)
7.4 Air, Compressed, dry and free from moisture, particulates, and oil. Air from a cylinder or a nonpulsating pump may be used. (Warning - Compressed gas under high pressure.)
7.5 Cleaning Reagent, Cleaning either in hot Nochromix (Warning - Corrosive health hazard oxidizer), or a 24h soak at room temperature in Micro solution.

NOTE 6 - Previously, chrome sulfuric acid was used in this procedure. Other test methods (for example, Test Method D1401) have demonstrated acceptable, statistically equivalent results when Nochromix or Micro is used to replace sulfuric chromic acid for cleaning.

7.6 n-Heptane, reagent grade. (Warning - Flammable. Harmful if inhaled.)

NOTE 7 - Other alternate solvents, such as toluene, etc., may be used in place of n-heptane.

8. Preparation of Apparatus
8.1 Clean the interior of the test vessel, including the air inlet and sinker, and all other glassware coming in contact with the sample, before each determination in the following manner:
8.1.1 Rinse away the oil residue with n-heptane (Warning - see 7.6) and acetone (Warning - see 7.3) and dry by air blowing.
8.1.2 Clean the apparatus by immersing in cleaning reagent in order to remove completely any traces of silicone.
8.1.3 Rinse with reagent water.
8.1.4 Rinse with acetone (Warning - see 7.3) and dry with clean compressed air (Warning - see 7.4).

NOTE 8 - Oil misting occurs during blowing. The test vessel should be in a hood, or the air outlet tube should be connected to a vent that removes the vapors.