Rules of Thumb
Mixing and Agitation
  1. Mild agitation is obtained by circulating the liquid with an impeller at superficial velocities of 0.1-0.2 ft/s and intense agitation at 0.07-1.0 ft/s.
  2. Intensity of agitation using impellers in baffled tanks is measured by power input and impeller tip speeds, as given in the table.
  3. In-line blenders are adequate when a contact time of 1-2 s is sufficient, with power inputs of 0.1-0.2 hp/gal.
  4. Power and Tip Speed requirements for agitation in baffled tanks

    Operation Power Needed hp/1,000 gal Tip speed ft/min
    Blending 0.2 - 0.5  
    Homogenous reaction 0.5 - 1.5  
    Reaction with heat transfer 1.5 - 5.0 10 - 15
    Liquid - liquid transfer 5 - 10 15 - 20
    Liquid - gas mixing 5 - 10 15 - 20
    Slurrying 10  

H I N T S  A N D  R U L E S
Drying and Solids Conveyors for Particular Solids Cooling Towers Compressors and Vacuum Pumps Crushing and Grinding
Extraction, Liquid-Liquid Crystallatisation from Solution Filtration Heat Exchangers Mixing and Agitation
Particle Size Enlargement Piping Pumps Reactors Refrigeration
Heat Exchangers Size Seperation of Particles Utilities, Common Specifications Vessels (Storage Tanks) Particle Size Enlargement
C O N T A C T   G L Y D E