Mechanistic approach to predicting cook-off hazards: Reaction kinetics verification

DTA/DSC (differential thermal analysis/differential scanning calorimetry) equipment is relatively inexpensive, readily available and can be used to test rate expressions once heat losses and samples are well-characterized. Heat transfer from the sample must be accounted for or sample ignition will be predicted for any temperature perturbation. For the preignition period, DTA/DSC techniques can be used to show consistency between rate expressions and ''ignition temperature''. However, the techniques are limited in identifying discrepancies in analytical models. The proposed oxidation mechanisms for titanium give ''ignition temperatures'' near experimental values, but the failure of predictions for smaller samples indicates that either additional processes must be accounted for in the experiment or that the oxidation models are incomplete. The disagreement appears not to result from the estimated uncertainties in oxidation rates, heat losses, or titanium depletion. Predicted oxidation rates give adequate energy for ignition, although other important processes seem to be involved. To resolve these processes, experiments using equipment designed to obtain transient information with multiple diagnostics is necessary.