Stainless steel is a durable, corrosion-resistant material that is used for a variety of sanitary process applications. From food and beverage processing to pharmaceuticals, chemical processing, and manufacturing, stainless steel is widely valued for its strength and high resistance to rust and corrosion. For this reason, it is the primary material used to manufacture mixers and agitators in many applications. Since most mixers and agitators come in direct contact with the product they are mixing, they must withstand exposure to moisture, corrosive chemicals, salts, and other factors that can compromise the material integrity of metal components.
Agitators and mixers are critical to an array of applications that require the smooth, easy-to-clean finish of stainless steel. Depending on the industry, a variety of mixer and agitator designs have been developed to facilitate the blending, mixing, and suspension of solids and liquids of varying consistencies. To help you find the best stainless steel mixer or agitator for your application, the team at Highland Equipment has provided a comprehensive summary of the most common mixers, their principles of operation, and common uses.
Axial Flow Mixers
Axial flow mixers include hydrofoil mixers, marine-type propellers, and wide hydrofoils. They operate at a high level of efficiency, with large flow rates that are ideal for blending materials with low to medium viscosity up to 3,000 to 5,000 cP. Axial flow mixers consist of a turning impeller or propeller in a stainless steel tank. As the impeller turns, it moves material parallel to the axis of the impeller’s rotation. This motion provides low shear, high-speed mixing of multi-liquid blends and liquid-solid suspensions. Axial mixers are often used as tank mixers for top-to-bottom blending, and are particularly effective for stratified mixtures and solid suspensions.
Mixed Flow Impellers
Mixed flow impellers use specially designed impellers to create combined axial and radial flow, both parallel and perpendicular to the impeller blade. They blend solids, liquids, and gases with medium efficiency at moderate speed, and are ideal for products with low to high-medium viscosity up to 25,000 cP. The moderate shear impact of mixed flow impellers makes them useful for blending a wider range of products and materials.
Radial Flow Impellers
Radial flow impellers are angled to direct product movement perpendicular to the impeller’s axis. Rushton impellers, open flat-blade paddle impellers, half-circle blade disc turbines, backswept open blade turbines, and backswept disc turbines are all examples of common radial flow impellers. The shape of flow passages and angles of the impeller vanes direct the product from the center of the tank to the outer walls, producing highly efficient agitation and high shear mixing. Radial flow impellers are ideal for use in sanitary stainless steel tanks for medium-high shear mixing of low- to medium-viscosity materials up to 10,000 cP. They can be used in single and multiphase mixing of liquid-liquid, liquid-solid, and gas-liquid blends.
Anchor mixers feature uniquely shaped impellers that are designed to fit close to the tank walls. This design allows the impellers to pull material from the wall surface and maintain agitation with primarily radial flow and medium-high shear. Anchor impellers are ideal for high viscosity products up to 100,000 cP, including cosmetics, pharmaceuticals, culinary sauces, condiments, and many more food related products.
Similar to anchor mixers, scraping agitators (scrape surface, swept surface) are distinguished by the scraper blades are designed to scrape the walls at slow speed, creating radial flow with medium-high shear. Scraping agitators are perfect for high-viscosity products up to 200,000 cP, and are often used in heated applications where material must be scraped from the walls to facilitate heat transfer throughout the tank and prevent the product from burning onto the tank walls.
High Shear Mixers
High shear mixers operate at extremely high speeds from 1,750 to 6,000 RPM, and are available with various impeller designs, including sawtooth (Cowles) dispersion impellers, rotor-stator shrouded turbine mixers, and Deflo, Sevin, and hybrid coaxial flow shear mixers. This type of mixer is valued for its high impact and vorticity, but requires more energy consumption than other designs. High shear mixers use high-speed rotors to push the product away from the axis toward a stationary stator, which creates the high shear necessary for homogenizing, dispersion, particle reduction, and emulsification processes.
Helical Type Impellers
Helical impellers are distinguished by the helical shape of the impeller, which is designed to provide close clearance. Depending on the shape and angle of the impeller, the product may be moved left-and-right or up-and-down. Helical impellers are designed for slow operation and extremely viscous products up to 150,000 cP. This type of impeller is often used to mix solids such as particulate and fibrous material into liquids and pastes.
Superior Mixers and Agitators for Your Stainless Steel Sanitary Process Applications
At Highland Equipment Inc., we are dedicated to providing superior quality mixers and agitators for our customers in a range of sanitary process applications from cosmetics and pharmaceuticals to food and beverage, dairy, and cannabis processing. All of our mixers and agitators are composed of passivated and polished stainless steel. In addition, we offer specialized polished finishes up to 7 Ra and electropolishing as needed for your particular application.
To learn more about our extensive selection of mixers and agitators suitable for stainless steel sanitary process applications, contact our experts today to request a quote.