Effect of External Temperature

Pyrotechnic and propellant devices that have been conditioned at a low temperature are also expected to bum slower than identical devices that have been conditioned at warmer temperatures. This is due primarily to the fact that the temperature rise that is required, via heat transfer from the reaction zone, for the succeeding layer of material to go from its initial temperature to the ignition temperature is a larger value for a cold device than a warm one. 

the temperature at which devices are stored prior to use can be a factor in the performance of the items if no temperature equilibration to a standard value is 

Source L. Lopez, F. Taylor, and R. Broad, The Replacement of Undesirable Barium Chromate by Iron (HI) Oxide in the Tungsten/Potassium Perchorate/Baiium Chromate/ 

Binder Delay System, 16th International Pyrotechnics Seminar, Jonkoping, Sweden, 1991. 

Note Composition Potassium perchlorate (33%), red iron oxide (18%), and tungsten (49%). Loading pressure 36,000 psi, column length approximately 0.64 inches. 

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To eliminate the effects of external temperature fluctuations in the calorimetric block, the calorimeter has two heat-flow meters, which are connected in opposition. The process under investigation is carried out in one of two identical calorimeter vessels, the other serving as the tare or reference element. This differential arrangement permits the compensation of parasitic phenomena such as external connections and reagent introduction heat, and it provides a good stability of the baseline. (From the development in Section II,A on thermodynamics it follows that for adsorption of gas in a Calvet calorimeter the heat measured corresponds to a differential molar enthalpy of adsorption because all other effects are compensated.)... 

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