Abstract: An apparatus for preparing a liquid material containing microbubbles includes a dispensing nozzle and a first positive displacement gas pump. The dispensing nozzles includes a material mixing channel, a rotary gas diffuser positioned in the material mixing channel, and a rotary mixer positioned in the material mixing channel downstream of the rotary gas diffuser. The rotary gas diffuser and the rotary mixer rotate about a common axis of rotation. The first positive displacement pump has a first gas outlet opening to the material mixing channel, which is directed at an outer circumference of the rotary gas diffuser.

Abstract: A device for mixing and dispensing a pair of flowable materials includes a housing containing a pair of control valves for controlling the flow of the two materials into a mixer tube mounted on an outlet end of the housing. The mixer tube contains a mixing element within the bore of the tube. A control device such as a pneumatic piston, moves a shaft which is connected to the mixing element, to move the mixing element linearly axially within the tube to prevent the leakage of materials from within the tube after the control valves on the housing are moved to a closed position. An air motor may be connected to the shaft for rotating the mixing element within the tube to enhance the mixing of the materials moving therethrough.