Selecting Rotor-Stator Configurations

Lab Homogenizer Rotor-Stator Configurations

Laboratory homogenizers such as offered by CAT Scientific are called on to perform multiple mixing, dispersing, and similar tasks to support R&D activity as well as to establish processing guideline that can be scaled up to commercial production.  Modular lab homogenizers allow researchers to pair multiple rotor-stator configurations to suit the specific emulsifying task at hand.  This is because variable speed homogenizer drive motors are designed to accept quick change-in, change-out of rotor-stator assemblies.  The question then, is how to choose lab homogenizer rotor-stator configurations.

Rotor-Stator 101

As the children are taught in “The Sound of Music” the beginning is a very good place to start.

A rotor-stator assembly consists of two primary components together with supporting gaskets and bearings.  These come in various diameters and lengths.  The assembly consists of (1) a rotating shaft (the rotor), one end of which is attached to the drive motor much as a bit fits into a portable drill, and (2) an equally aptly named stationary stator that surrounds the shaft and locks into the drive motor casing.

The working end of the rotor is machined with slanted knife-like edges designed to complement sharply machined slots at the open end of the stator.  When the homogenizer is operating, product is drawn into the open end of the stator and whipped with tremendous force by the knife-edged rotor through the slots of the stator, thus accomplishing the homogenizing activity.  This operating end of the system is called the generator.

Choosing Lab Homogenizer Rotor-Stator Assemblies

Rotor-stator assemblies are designed to perform a wide variety of tasks.  This post covers four very basic points to consider when selecting generator configurations.  To obtain detailed recommendations for your particular requirements please ask a question and we’ll get back to you with the answer.

1.    How deep is your mixing vessel?  Your laboratory homogenizer mounting bracket offers some flexibility but the generator should not be less than 10mm from the bottom of the vessel.    Similarly, if the generator is too close to the surface of the medium splashing may occur. This information will help you determine the length of your rotor-stator assembly.
2.    What is the viscosity of the material being emulsified?  General classifications are fine, low viscosity and viscous, each of which can be processed most efficiently by selecting the proper rotor-stator assembly.
3.    What is the physical characteristic of the material? If you are working with coarse stringy material you should use a knife grade rotor-stator assembly.
4.     What is the chemical composition of your material?  Abrasive or corrosive media require special consideration in specifying seals and bearings.

Don’t Forget Lab Homogenizer Maintenance!

Even if you repeat analysis with the same samples time after time, but especially if you vary the material being disrupted you must have a standard operating procedure to thoroughly clean the components of your rotor-stator configuration.  This helps avoid cross contamination and also serves to protect your investment in your CAT homogenizers.  For more information on maintenance please visit our post on cleaning tips for homogenizers.