Next generation of consumer aerosol valve design using inert gases

The current global consumer aerosol products such as deodorants, hairsprays, air-fresheners, polish, insecticide, disinfectant\ud are primarily utilised unfriendly environmental propellant of liquefied petroleum gas (LPG) for over three decades.\ud The advantages of the new innovative technology described in this paper are: (i) no butane or other liquefied\ud hydrocarbon gas; (ii) compressed air, nitrogen or other safe gas propellant; (iii) customer acceptable spray quality and\ud consistency during can lifetime; (iv) conventional cans and filling technology. Volatile organic compounds and greenhouse\ud gases must be avoided but there are no flashing propellants replacements that would provide the good atomisation and\ud spray reach. On the basis of the energy source for atomising, the only feasible source is inert gas (i.e. compressed air),\ud which improves atomisation by gas bubbles and turbulence inside the atomiser insert of the actuator. This research\ud concentrates on using ‘bubbly flow’ in the valve stem, with injection of compressed gas into the passing flow, thus also\ud generating turbulence. Using a vapour phase tap in conventional aerosol valves allows the propellant gas into the liquid\ud flow upstream of the valve. However, forcing bubbly flow through a valve is not ideal. The novel valves designed here,\ud using compressed gas, thus achieved the following objectives when the correct combination of gas and liquid inlets to the\ud valve, and the type and size of atomiser ‘insert’ were derived:\ud 1. Produced a consistent flow rate and drop size of spray throughout the life of the can, compatible with the current\ud conventional aerosols that use LPG: a new ‘constancy’ parameter is defined and used to this end.\ud 2. Obtained a discharge flow rate suited to the product to be sprayed; typically between 0.4 g/s and 2.5 g/s.\ud 3. Attained the spray droplets size suited to the product to be sprayed; typically between 40 mm and 120 mm.