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Black powder is often used as propellant in the fireworks industry, but the sulphur in the black powder will pose great risks to the environment and human health. Although there are sulphur-free propellant with metal powder and smokeless propellant prepared from expired military gunpowder to solve the problem, the high sensitivity and huge explosive power of the mental powder and instability of the expired military gunpowder lead to low security in actual application. Therefore, sulphur-free propellant which can replace black powder is urgently needed. In this study, a discharge height test was conducted for the sulphur-free environmental protection formulation [potassium perchlorate (70%), potassium hydrogen terephthalate (10%), carbon (11%), ferrocene (1%), phenolic resin (7%), calcium stearate (2%)] optimized by an orthogonal test. The thermal explosion in critical temperature was used to determine the thermal stability of sulphur-free propellant and black powder, then compared with combustion heat. The preesure-time test was used to compare the peak pressure of this two propellant. The impact, friction and flame sensitivity were also measured. It is thought that sulphur-free propellant can replace the black powder as the new environmental-friendly propellant in the fireworks industry with low sensitivity and excellent storage performance, and have great potential in application.

This study analyzed the effects of both water mist and water mist with different additives on cooling of cooking oils during fire extinguishment. The sizes of water mist drops with different additives were measured using a split-type laser particle analyzer. Full-scale extinguishment–cooling experiments using different fire extinguishing agents and oil temperatures were also conducted. The boiling over layer formed during the cooling of cooking oil using water mist could significantly enhance the cooling rate. Moreover, the expanding rate of this boiling over layer is related to oil temperature and water mass in oils. Although additives reduce water evaporation and hinder oil cooling, such additives also inhibit the expansion of the boiling over layer, thereby reducing the risk of secondary damage caused by abundant oil overflow after the fire extinguishment.

Cooking oil fires which happened in the kitchen or hotel have become quite popular over the last decades. Compare to other types of fires, cooking oil fires are very difficult to extinguish. Both foam and powder can effectively extinguish the flames over the oil surface but they are very difficult to cool the oil below its auto-ignition temperature and to prevent it from re-ignition due to their limited cooling capacity. Moreover, water mist with additives may be applied to provide additional improvements in terms of suppression effectiveness and temperature control of cooking oil fires. The present work establishes a series of home-scale experiments to study extinguishing mechanisms and effectiveness of pure water and water mist with additives against cooking oil fires. The thermal transient within the test chamber has been evaluated during the fire development as the main quantitative parameter. Results showed that water mist is shown to be efficient in cooking oil fires control, especially endowed with the chosen additives which demonstrated that water mist with additives would extinguish cooking oil fires through physical and chemical mechanisms. Furthermore, the change in fire extinguishing efficiency differs for different additives and mass fractions of the additives.