A reductant delivery unit with a freeze prevention selective catalytic reduction solution for a vehicle having an exhaust flow path, comprising:
- an exhaust system having a selective catalytic reduction portion where a mist of a solution containing urea, water and gas bubbles is mixed with exhaust gas from the exhaust system;
- a tank containing a solution of urea and water and including an air space above the solution;
- a device disposed at least partly within the tank and configured to selectively generate a pressurized solution of urea, water and air bubbles at an outlet of the device, the device comprising a compressed gas canister in fluid communication with a pump, the outlet of the device being an outlet of the pump;
- a selectively pressurized solution supply line, in fluid communication with the outlet of the device, the supply line containing the solution of urea, water and gas bubbles, where the solution is present in the selectively pressurized solution supply line in a pressurized state and a depressurized state, where the gas bubbles are smaller and have less volume when the solution is in the pressurized state and the gas bubbles are larger and have greater volume when the solution is in the depressurized state, thereby creating freezing air space when the solution is depressurized;
- an injection head connected to the selective catalytic reduction portion for introducing the mist, said injection head is connectable to said supply line and receives said solution from said supply line, wherein said selectively pressurized solution is present in said injection head and has gas bubbles that limit the potential of ice to exert its blocking force on fluid path components of the injection head, wherein said injection head includes a flow path with an inlet and an outlet, a fluid flow path through a body of the injection head including an injector flange mounted to a metallic boss that is in communication with the vehicle's exhaust flow path, a gasket sandwiched between the injector flange and a mounting surface on the exhaust boss to permit the solution to pass from the outlet to the exhaust flow path;
- wherein the selectively pressurized solution contains gas bubbles that prevent the freezing of the solution that is contained within the body of the injection head;
- a pressure relief valve connected to the pressurized solution supply line for causing solution to transition between the pressurized state and the depressurized state by relieving the pressurized state of the solution in the solution supply line, the pressure relief valve forming an injector of the reductant delivery unit with the injection head, the injection head being downstream of the relief valve, relative to flow of the solution through the pressure relief valve and the injection head, the pressure relief valve opening and closing based upon an amount of pressure in the pressurized solution supply line without being controlled by a controller.