Rationale

"External surfaces of weights shall have a finish (Ra) of 3.2 µm (125 µin.) or less as specified in ASME B46.1." Proposed change: change shall ? should. When interpolated zero force readings are used, the zero-corrected reading at each applied force in the series shall be calculated by linear interpolation between the initial and final zero readings, in proportion to the ratio of the applied force to the maximum force in the series, as follows: Vcorr(Fi) = (Fi / Fmax) × (V(0initial) - V(0final)) + V(Fi) (5) where: V(Fi) = the indicated output reading of the force-measuring instrument at applied force Fi, V(0initial) = the zero force reading taken immediately before application of the series of forces, V(0final) = the zero force reading taken immediately after removal of the series of forces, Fi = the applied force at the i-th step of the series, and Fmax = the maximum applied force within the series. The deflection at Fi shall then be calculated as the difference between Vcorr(Fi) and V(0initial). This correction assumes the zero drift between V(0initial) and V(0final) to be linear with respect to the applied force within the series; the method shall not be applied where the magnitude of (V(0initial) - V(0final)) exceeds the zero return error criteria of 8.2.2.1. Current wording (§6.3.3): "…monitor and record the temperature as close to the elastic torque measurement standard as possible. The temperature should not change more than ±1 °C during calibration." Proposed wording: "…The temperature shall not change more than ±1 °C during calibration." Rationale: ASTM E74 already treats the analogous requirement as a shall. E2428 involves a moment arm in addition to weights; thermal effects on MU are larger than in E74, not smaller. Aligning the verb with the intent (control conditions during calibration) makes the requirement enforceable. The gravity formula in section 5 is incorrect and needs removed. 5.3.2 For the purposes of this practice, g can be calculated with sufficient uncertainty using the following formula: where: g = local acceleration due to gravity, m/s2, Ø = latitude, h = elevation above sea level in meters. NOTE 1—Eq 2 corrects for the shape of the earth and the elevation above sea level. The first term, which corrects for the shape of the earth, is a simplification of the World Geodetic System 84 Ellipsoidal Gravity Formula. The results obtained with the simplified formula differ from those in the full version by less than 0.0005 %. The second term combines a correction for altitude, the increased distance from the center of the earth, and a correction for the counteracting Bouguer effect of localized increased mass of the earth. The second term assumes a rock density of 2.67 g/cm3. If the rock density changed by 0.5 g/cm3, an error of 0.003 % would result.