Fundamentals of Dispersion - A Quick Reference Guide
How Dispersion Works
Dispersion is a high-speed, high-shear process requiring more horsepower to successfully achieve than simple agitation for smaller batch sizes. As the dispersion blade turns, particles contact the blades and are broken apart. In the intense turbulence surrounding the blade, particles collide at high speeds and are further broken apart.
Beyond the zone of attrition the now broken down material is thoroughly mixed and particles are dissolved or dispersed by the horizontal laminar flow extending from the blade. The flow then divides into upward and downward components at the vessel wall ensuring complete circulation.
How to Get the Most From Your Dispersion
You need to determine the optimum blade size, blade position and material depth for your project to get the best results. The blade size should measure about 1/3 the diameter of the vessel in which the blade will be used. The blade should be placed about one full blade diameter off the vessel bottom.
The maximum depth of the material should not exceed three times the diameter of the blade. The depth above the blade should not be less than the amount below the blade. Round vessels almost always provide better dispersion than square vessels because they have no “dead areas” in the corners.
When choosing your blade design, know that our blade designs A-D generate similar shearing energy (which is the hydraulic tearing apart of particles). However, our design C blades shear slightly less and generate less heat than others due to the lower number of teeth per blade.
To help choose the right dispersion blade, follow our guide.
For more information on how to get the most from dispersion, take a look at our infographic.
How to Calculate Shear
Shear is to a great extent determined by the tip speed (or rim velocity) of the blade. The faster the tip speed, the higher the shear. Tip speed should generally be from 4,000-6,000 feet per minute. The diameter of the blade will determine the RPM the shaft must turn to give the recommended tip speed. To calculate tip speed in feet per minute multiply shaft RPM x .262 x blade diameter in inches.
If you have more questions or need help choosing the parts for your system we are always here to help.