A tank on a firefighting aircraft initially is loaded with water. A polymer gel emulsion vessel is provided but gel emulsion is not activated and mixed with water in the tank until such polymer gel preparation is initiated by an operator. When initiated, a pump pulls water from the tank and returns water back to the tank with a dose of gel emulsion supplied therein. Double elbows and/or the pump impeller fully activates the polymer gel. The activated polymer gel is mixed within the tank by one of a variety of systems including sparging with air, routing of return water from the pump through nozzles and providing a baffle for generating circulatory mixing flow within the tank, or utilizing a mixer element which moves dynamically within the tank. Hydrodynamic forces associated with the aircraft passing over a body of water can power dosing of the water with polymer gel emulsion.

The boundary layer drum mixer is an apparatus which can pass through the narrow top port of a standard chemical drum or bulk container without the need to disassemble any part of the mixer or the vessel. The invention is an enclosed system with an internal arrangement of impellers and stators which draw liquid-based media from the adjacent vessel and strategically distributes it throughout the vessel through an array of outlet ports. The strategic mixing requires low energy input, minimizes the risk of media aeration and works with a wide range of fluid levels. The apparatus imparts no net external torque, and therefore, requires no rigid mounting. The upper impeller flow positively entrains particles or liquid phases that tend to float. The lower impeller flow positively entrains particles or liquid phases that tend to sink and/or remain static in boundary layers against or near the vessel walls and base.

Methods for reducing corrosion or fouling in a pipeline can include identifying a location in the pipeline where inhomogeneities in the fluid produce the conditions that promote corrosion or fouling. A mixing unit can be installed based on the identified location with blades of the mixing unit positioned inside the pipeline. Homogeneity of fluid in the pipeline can be increased downstream of the mixing unit by flowing the combined first fluid and second fluid past the blades of the mixing unit.