Rationale

The microscale combustion calorimeter signal exhibits thermal drift of 5-7 W/g over the test duration and random temporal fluctuations of 1 W/g during the test when no test specimen is present during normal operation of the instrument (18). The combined effect is called baseline drift and noise, and it varies from test to test so it must be corrected in situ. Baseline drift can cause significant error in the measurement of flammability characteristics if the combustion signal of the sample is of comparable magnitude to the drift. The detection limit of the instrument is 3 W/g (18) when the calorimeter signal is corrected for baseline drift, so the limit of quantification (LOQ) is 10 x 3 W/g = 30 W/g. This ballot provides a method to correct the calorimeter signal for baseline drift when the maximum deflection of the calorimeter signal during sample combustion is less than the LOQ of 30 W/g. The baseline correction method is described in a new Appendix X3 to the standard and supporting references have been added. This ballot adds this caveat to Limitations in section 6 and clarifies Calibration in section 8. Requirements for when Appendix X3 apply are given in Section 12.