Downloaded from https://www.everyspec.com . . . ,. MIL-STD-2031 (SH) 40.5.7 Additiorml data. Should percent, the oxygen index shall also be the measured oxygen index at 300 be lower measured at 200 (390 “F). This ridditional data than 21 will help to define the temperature index profile more cornpletelv. 50. REPORT 50.1 Precision of measurement. Precision of measurement may be determined statistically, in accordance with ASTM D 2863, if the material is sufficiently well behaved under the experimental conditions of the test.
From a practical standpoint, for specimens from the same sample, agreement to within 0.5 percent oxygen is possible; for specimens from different samples, agreement within 1.0 percent oxygen is possible. By the very nature of the materials under examination, it is unwise to expect too great a precision of measurement unless the material is of the nature of a “secondary standard” where behavior of the material is predictable. Poly(methylmethac~late), PMMA, is such a secondary standard for oxygen index measurements. The expected oxygen index range for PMMA, under ambient conditions, 17.0-17.5 percent.
PMMA is useful for determination of instrument performance and for initial training of technical personnel. S0.2 Report eontmcts. Test reports shall include the following: a. Nomenclature manufacturer and code markings to identi~ the material evaluated and the b. Dimensions of the test specimens c. Testing conditions of the oxygen index measurements d. Individual oxygen index values, em-responding temperatures, and the average oxygen index value for the particular set of measurements c. Tabular and graphic representations of the temperature index profile f.
A description of any unusual speeimen behavior such as prolonged glowing combustion after flameout, charring, dripping, bending, erratic burning, or exeessive smoke evolution.