Apparatus and method for dispensing a mixture of a gas and a fluid material

A method for dispensing a mixture of a fluid material and a pressurized gas, the method comprising:

• opening a dispenser to dispense an amount of the mixture from the dispenser and to supply the fluid material to a mixing chamber coupled with the dispenser;
• in response to opening the dispenser, actuating a gas injection device to inject the pressurized gas from an outlet of the gas injection device into a stream of the fluid material flowing through the mixing chamber by pneumatically moving a piston to cause a portion of a needle attached to the piston to separate from a first seat so that the pressurized gas flows past the first seat and towards the mixing chamber;
• while the pressurized gas is flowing past the first seat, allowing a plunger of a flow control element to move against a biasing force relative to a second seat located between the first seat and the outlet to provide a first condition in which the pressurized gas flows past the second seat and then to the outlet so as to flow into the fluid material in the mixing chamber;
• combining the pressurized gas with the stream of the fluid material flowing through the mixing chamber to form the mixture;
• and
• directing the mixture from the mixing chamber to the dispenser,
• wherein the actuating of the gas injection device by pneumatically moving the piston further includes pneumatically moving the piston against a biasing force provided by a biasing element interacting with the piston and needle to bias the needle to move towards engagement with the first seat.