Stainless Steel Mixing Tanks
Most mixing tanks are built from 304 or 316 grade stainless steel, two of the most common grades of the metal. Mixing tanks are used in many different ways and are utilized in the chemical, food processing, water treatment and agricultural industries to mix dry chemicals, blend dough, purify water through sedimentation and combine varieties of grain, for example. Mixers can operate at a range of different temperatures and pressures and come in many varieties; the commonality is that in most instances, movement needs to be maintained to ensure that the components and materials are mixed together. The agitator is typically the moving mechanism and the device inside the tank that does the mixing. These vary greatly in size, shape and desired results, and there are many types, including homogenizing, propeller, screw, single rotor and plow mixers.
Stainless steel is made from steel and a variety of alloys that are melted together at high temperatures then cooled and hardened. It is rolled into sheets of metal that are welded or bolted together; welded seams are watertight and are therefore used most frequently for mixing tanks. The tanks are sometimes mounted on stainless steel legs to allow for underclearance so the contents can be poured into a truck or other container while others are fitted with pipes that transport the mixture. The top of these tanks can be welded or bolted on; lids are also an option. There is always at least one opening, called a manway, and usually a variety of inlets and connections, depending on the application. The bottoms of the tank can be flat, sloped, dished or conical, according to how the materials are to be removed, how viscous the material is and what kind of mixing apparatus is inside. The three main kinds of agitators are paddle, ribbon and static mixers. Paddle mixers use a rotating shaft with fixed arms and paddle-shaped feet and are useful for mixing slurry. Ribbon mixers have long ribbon-like paddles that turn around a central axis and can be used for shearing material or removing lumps from flour, for example. Static mixers actually have no moving parts but instead force liquids around carefully placed obstructions that divide, rotate and divert the flow before recombining the material; inks or paints can be mixed using this system. Stainless steel heating or refrigeration jackets are also frequently used on mixing tanks to maintain a consistent temperature.
