Mixing 101: Optimal Mixer Design

4 FACTORS FOR OPTIMAL CONFIGURATION

Getting the right mixer for the job involves so much more than simply purchasing a standard unit off-the-shelf.

There is an art to configuring a mixer that will optimize the results of an application. Selecting a mixer based solely on horsepower or RPM requirements can produce less than optimal results, and even damage your product through excessive shear.

As we discussed in an earlier post, we first need to understand the 4 Factors for Configuring a Mixer, which are:

  1. Tank Type & Volume
  2. Fluid Viscosity
  3. Specific Gravity
  4. Environment & Process

Once a Dynamix Sales Engineer understands these factors in relation to your application needs, we are ready to configure a mixer that will both maximize your investment and control your product quality.

Considerations for Optimal Mixer Selection

Typically, an industrial agitator consists of four main segments:

  1. Drive
  2. Mount
  3. Shaft
  4. Impeller

With each of these segments, there are a number of important considerations to enable optimal configuration of the mixer.

1. Mixer Drive (Inclusive)

An industrial mixer’s drive typically consists of a motor with the appropriate horsepower and a gearbox with the correct torque capacity.

Motor

The agitator motor needs to be sized to meet requirements for appropriate horsepower. Most agitators come with electric motors, but on smaller-size applications, air and hydraulic motors are used as well.

Gearbox Service Factor

Any gearbox can function for a drive but it is preferable to have a unit that has been modified or designed specifically for agitator service.

On a low speed shaft, heavy-duty bearings should be used to handle the increased stress and overhung loads.

To learn more about the benefits of gear reduction and the differences between air and electric motors, check out our related posts:

 

2. Mounting

The mount on a mixer is determined by multiple factors. The basic starting points to assess mounting requirements are:

  • Tank Size & Type
  • Mixer Size & Orientation
  • Operating Environment
  • Available Space
  • Desired Flow Pattern

Determining whether your tank is open or closed, cylindrical or square, the size of the space allowance in the mixing area – are important factors in which mount type will be selected for your mixer configuration.

Dynamix has a variety of options available for tanks of all sizes, drums, and totes, including bridge, clamp, plate, flange, pedestal, and side entry mounts.

Dig a little deeper into the variety of mounting options, read our related post:

 

3. Mixer Shaft

The shaft of a mixer is fitted according to your tank size, but there are several important considerations to take in to account. Considerations for shaft selection include: Shear and Tensile Stress, and Critical Speed

Shear & Tensile Stress

Shaft stresses are based on the level of torque produced by the drive, and positioning of the turbines on the shaft, which are factored based on the requirement of the process. Dynamix uses service factors on its shafts to ensure a rugged long-lasting mixer design.

Critical Speed

The other factor to consider is the critical speed or natural harmonic of the shaft. All shaft assemblies on our Industrial Agitators are designed to operate well below the first critical speed (CS).

4. Impellers

An impeller is a crucial part of mixer optimization. Since it is the component that does the actual mixing and produces the desired result, it must be designed and sized to maximize efficiency.

Due to the importance of impeller selection, there are multiple considerations: Geometry and Position, Material and Coatings

Geometry & Impeller Positioning

Factors to consider include the size and design of the impeller, the type of flow desired, and the size and shape of the mixing tank.

Impeller Types

There are many types of impellers, these are examples of some standard types:

  • Radial Blade – Primarily used to provide shear in gas dispersion and for low liquid level mixing with a radial flow.
  • Propeller – Typically used today on small high-speed portable mixers because their cost increases exponentially with size.
  • Pitched Blade – The workhorse of the mining industry. It has high pumping rates and is an excellent mixing impeller.
  • Airfoil Blade – The most efficient mixing blade when it comes to pumping because it utilizes laminar flow to decrease drag and increase pumping/mixing.
To learn more about impellers and flow patterns, check out our related posts:

Solution Assurance

Solution AssuranceOur engineers are highly skilled at configuring a mixer suit your process, application and product. When given the proper application specifications, we can configure a mixer that will perform as expected, and meet your process needs.

With our mixers, we offer our Solution Assurance, our process guarantee.

If you want to know more about how Dynamix can configure a solution for you, post a comment or email us at [email protected]

 

 

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Brian James the author

Dynamix Agitators incorporates over 45 years of industrial mixing experience into its industrial mixer models and the processes they are part of. Our mixers and agitators are configured to suit your process and application.