For applications from typical to exotic.

Dyna/Mag™ magnetic mixer drives are used in labs and process plants for such common applications as hydrogenation, nitration, oxidation, and isomerization. They also find use in polymerization and catalytic reaction studies, where they drive catalyst baskets - such as the "falling basket" assemblies custom-designed by PPI for dual-phase studies.
What's more, Dyna/Mag drives are now being used in the development of materials that require high-turbulence mixing in which fluid shear is a key factor. They are even finding use in non-mixing applications - such as powering fans in pharmaceutical sterilizing equipment, where they prevent leakage of purge gases and eliminate potential contamination from lubricants.

Selecting the optimum mixing system.

For any application, choice of the proper impeller is critical for success. Impellers can be divided into two general classes, axial flow or radial flow, depending upon the angle the blade makes with the axis of the drive shaft.

Axial flow impellers make an angle of less than 90° with the mixer shaft. Figures 1, 2, and 3 illustrate this type - they are the propeller, fan turbine, and pitched paddle.

Uses: Axial flow impellers are used at high speeds to promote rapid dispersion and are used at low speeds for keeping solids in suspension.

Radial flow impellers have blades that are parallel to the axis of the mixer shaft. The smaller, multi-blade types (figure 4) are called turbines. Larger slow-speed impellers, with two to four blades (figure 5), are known as paddles, while other larger two-sided types (figure 6) are known as gate or anchor impellers.

Uses: Turbines, which come in a variety of types, provide excellent circulation of fluid throughout the mixing vessel. The diameter of a turbine impeller is normally between 0.3 and 0.6 of the tank diameter. Paddles are used at slower speeds and normally have a diameter greater than 0.6 of the tank diameter. These two types are most often used for large scale mixing of solid/ liquid suspensions. Gate and anchor impellers are used to sweep the entire peripheral area of the tank - both walls and bottom.

The Gaspersator^TM impeller (figure 7) consists of a hollow shaft and a flat blade turbine.

Uses: The Gaspersator impeller promotes rapid reactions between gases, liquids, and solids in high-pressure reaction vessels. As the shaft rotates, the turbine creates suction, drawing gas in at the top of the shaft. Gas travels through the shaft and exits as bubbles that are thoroughly dispersed by the turbine blades. The total action achieves optimum dispersion of both gases and solids within the liquid.

Baffles: Typical baffles are flat vertical strips set radially on the vessel wall (figure 8). The standard baffle width is one-twelfth of the tank diameter. Even in large vessels, four baffles typically provide the optimum effect.
Uses: High-impeller speeds lead to the formation of a vortex, often accompanied by air entrainment and an oscillating surge within the vessel. The use of baffles overcomes these problems and results in a large amount of top-to-bottom circulation. For agitation of higher viscosity fluid, baffles are typically set out one-half the baffle's width from the vessel wall to prevent accumulation of product.

Helical mixers are a variation of the gate or anchor style; such impellers (figure 9) include a blade that acts like an auger.
Uses: A helical impeller promotes thorough mixing of highly viscous compounds such as those often found in polymer reaction studies. The impeller fully sweeps the bottom and sides of the vessel, and provides maximum agitation of the full volume with the least torque and stress.

Delivering the necessary power.

The power demand created by an impeller is based on two variables: fluid circulation (pumping capacity) and fluid shear rate. The pumping capacity of an impeller is defined as the volumetric flow rate normal to the impeller discharge area. The fluid shear rate is based on the velocity of the fluid leaving the tips of the impeller.
A large impeller running at slow speed has a high pumping capacity and a low fluid shear rate, while a small impeller at high speed has a high shear rate and low pumping capacity. This means the power input may be distributed in different ways by selecting the appropriate ratio of impeller-to-tank size.
Through the latest rare-earth magnet technology, the Dyna/Mag drives offer high power for their size. The largest model can deliver up to 1,000 in-lbs (117 Nm) of static torque. Their attractive torque-to-size ratio makes Dyna/Mag drives natural replacements for mechanical drives on laboratory, pilot plant and process reactors.

Advanced designs open the application possibilities.

The Dyna/Mag magnetic drive is a new generation design, offering advantages over mechanical mixers and most of the magnetic mixers in use today. In research and process applications, the Dyna/Mag drive delivers:

Leak-tight operation. With no rotary seals, even the most hazardous and toxic gases and fluids can be handled safely.
Contamination-free agitation. With no packing or lubrication, no impurities can be introduced.
High torque. Non-Newtonian and high-viscosity compounds can be mixed easily. Integral cooling maintains optimum magnet efficiency.
Easy cleaning and maintenance. A quick-opening pressure closure allows rapid disassembly. A purge connection in the pressure closure is available.
Speed indication. A Hall-effect sensor allows monitoring of the exact rotational speed of the agitator shaft.

Complete technical assistance.
PPI representatives and field sales engineers will provide consultation. They can assist you in selecting the most economical Dyna/Mag mixing system for your application and can offer advice on refurbishing existing reactors by replacing obsolete packed or magnetic drives with a new, more powerful PPI Dyna/Mag. PPI Dyna/Mag magnetic mixers can be adapted or retrofitted to vessels or reactors originally produced by other manufacturers as well as those produced by PPI.

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© 2002 Pressure Products Industries, Inc.
Dyna/Mag and Gaspersator are trademarks of PPI. Hastelloy C276 is a trademark of the Cabot Corporation.

Experts in the design, installation, and manufacturing of high pressure products, Pressure Products Industries, Inc. can provide you with the equipment for a variety of applications. PPI specializes in the manufacturing of hydrogen gas compressors, diaphragm compressors, oxygen gas compressors, custom chemical reactors, and equipment for electronic gases. Our professional and skilled engineers and design groups strive for optimum functionality, safety, and maintainability among all of our products. Contact PPI for the best products and services available in the high pressure product industry.
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