US Patent 7926741 Aerosol dispenser

An aerosol dispenser has a canister to contain a liquid product to be dispensed together with a propellant present at least partly as a gas and valve to control the release of the liquid product from the canister. The dispenser also has a vapor phase tap for introducing a portion of the gaseous propellant into the liquid product as it is dispensed. The dispenser has a flow control device for varying the rate at which the propellant has is introduced into the liquid product through the vapor phase tape in dependence on the pressure of the contents of the canister. The flow control device can be used to reduce the amount of propellant gas bled into the liquid product, particularly when the dispenser is full and the pressure in the canister is high, as a way of conserving the propellant gas.