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The static mixer is a tube-like device that is used for mixing fluids, such as two liquids; two gases; or mixing a gas into a liquid by dispersing the gas into an immiscible liquid — a liquid incapable of forming a solution. A static mixer may be made with materials such as stainless steel, Teflon, or polypropylene, among others. The device itself consists of only a few parts, including a housing tube that can be cylindrical or square in shape, and baffles that are made out of plastic or metal alloys. This housing tube holds all the components within the mixer and can vary in diameter, ranging between 0.23 inches (6 mm) and 19.7 feet (6 m). The baffles are the mixing components and have a variety of shapes.
Most often, the fluids mixed in a static mixer are two liquids or a gas and a liquid. The mixing fluids do not necessarily have to be reactive, and sometimes the process results in a simple mixture or compound. One type of mixer, called a helical static mixer, has baffles that are helically shaped and cut into sections where a slight rotational modification allows for fluid mixing. This is called flow division, and it allows stratification to exponentially increase fluid mixing. A helical static mixer is often used for the mixing and application of adhesive materials for a variety of fields and disciplines.
This mixer works well with viscous liquids that react and form another viscous liquid or a solid product. One example of this type of product would be synthetic resins, which can be dispensed and delivered to certain locations where they will harden into a polymerized condition. Hardware stores sell these types of mixers for household application and they are often disposable and have packages of acrylic and epoxy adhesive materials. These kinds of mixers may also be found in a dentist’s office, where they are used for mixing sealants that are placed within a patient’s mouth for production of molds for bridges and cements. This kind of static mixer can be used in larger scale industrial applications as well, such as patching bodies of automobiles or waterproofing a boat.
In addition to these types, there are also static mixers with a blade design, which are primarily used for applications of low and medium viscosity. The mixer’s baffles also spin, which increases the amount of mixing. Another type of static mixer is the wafer style, where chemicals with light viscosity are mixed into water streams with high velocity.
A static mixer is not a tube like device. Some are. Modern ones are precision engineered and tabbed orifice plates. The use of computers and computational fluid dynamics has greatly improved static mixer design.