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Cole-Parmer Technical Library

Mixer Selection Guide

Mixer Applications

  • Laboratory Mixers are available with permanent magnet, universal, or air-drive motors. Choose from different mixer mounts for mounting on tanks or stands. Our variety of impellers and paddles lend versatility to the mixer you select.
  • Industrial Mixers are available with electric or air-driven motors for up to 1/2 hp. Fixed- or variable-speed and direct- or gear-driven options are available. Select from external drum lip clamp, C-clamp, or 2" NPT(M) mounting style.
  • Reversible Dispersion and Double-Helix Mixers are ideal for mixing fine powders, mixtures with solids, and highly viscous fluids. Available in universal or air motor models.
  • Static Mixers let you mix fluids as you pump them through a pipe line. The fluid moves through the mixer in an alternating clockwise/counterclockwise motion to ensure homogeneous product. They are virtually maintenance free and need no spare parts.

A Guide to Mixer Selection

Cole-Parmer offers a broad selection of mixers and mixer products to suit almost any application. Proper selection of a mixer requires knowledge of certain application variables:

  1. Container capacity: tank diameter and batch height
  2. Liquid viscosity: Different types of liquids display different characteristics when force is applied. Four most common types of liquid behavior are listed below—all of our mixers are to be used with fluids exhibiting Newtonian, pseudoplastic, or thixotropic behaviors.
  3.     Dilatant Liquids—viscosity increases as shear rate increases. Mixers can bog down and stall after initially mixing such liquids. Dilatant liquids include slurries, clay, and candy compounds.
        Newtonian Liquids—viscosity remains constant regardless of shear rate or agitation. As mixer speed increases, flow increases proportionately. Newtonian liquids include water, mineral oils, and hydrocarbons.
        Pseudoplastic Liquids—viscosity decreases as shear rate increases, but initial viscosity may be sufficiently great to prevent mixing. Typical pseudoplastic liquids are gels, latex paints, and lotions.
        Thixotropic Liquids—as with pseudoplastic liquids, viscosity decreases as shear rate or agitation increases. When agitation is stopped or reduced, hysteresis occurs and viscosity increases. Often the viscosity will not return to its initial value. Thixotropic liquids include soaps, tars, shortening, glue, inks, and peanut butter.
  4. Torque requirements: the rotational force required of the mixer motor—measured in in-oz or in-lb.
  5. Horsepower (hp) requirements: the efficiency required of the mixer motor with regard to torque (in-oz) and to the rotation speed (in revolutions per minute—rpm) as defined by the following equation:

    hp = (in-oz x rpm)/1,008,400

  6. Rotational speed (rpm) and diameter of mixing propeller: A small increase in the rpm or diameter greatly increases the power required for mixing. This relationship can be expressed as follows:

    Power α rpm3 x dia5

  7. Duty cycle: the time interval devoted to starting, running, stopping, and idling when a device is used intermittently.
  8. Power supply: electric (115 or 230 VAC) or air-drive mixers for areas where electricity is unsafe or impractical.
Related Links: Printer-friendly page

Complete Selection of Mixers and Blenders

Positioning a Mixer in a Cylindrical Vessel

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