Axial Flow Impeller

The impeller imparting movement of fluid from top to bottom inside the tank.

Agglomeration

Re-arrangement of zeta potential  (surface forces) in finely dispersed particles for recombining into large particles.

Baffles

Vertical plates attached to tank walls to prevent uncontrolled swirling of liquid contents. Helps in cutting vortex and promoting turbulence.

Bearing Life

Represented as L10 life, which is the number of hours of operation under a given set of load conditions during which a bearing has a 10% chance of failure.  It is 1/5^th of the average life.

Critical speed

Rotational speed corresponding to first lateral natural frequency of mixer shaft and impeller

Dilatant

Non-newtonian fluid with shear thickening behaviour.  With this fluids, viscosity increases with increasing shear rate. This is  time independent.

Deflection

The temporary bending below the elastic limit of a shaft, for instance.

Dispersion

The action or result of combining two immiscible fluids.  In impeller mixing and agitation, dispersions may be formed with two liquids or a liquid and a gas (liquid phase continuous)

Dry-Well

A weir or dam  designed around the output shaft of a speed reducer unit to prevent leakage of lubricant.

Harmonic ratio

Ratio of operating speed,  or any driving frequency to a natural frequency.

Immiscible

A condition in which two liquids fail to blend, and instead form two separate liquid phases with different properties and compositions. Interfacial tension exists along the surface separating the two phases.  In typical liquid dispersions, one or the other phase is continuous and other dispersed at given conditions.

Impeller

The general term used to describe the debice attached to the rotating shaft, which causes fluid motions.  More specifically called turbines, anchors etc..

Laminar Mixing

Laminar flow is associated normally with high-viscosity liquids. Under laminar flow conditions, inertial forces quickly die out under the action of the high viscous forces. Therefore, rotating impellers must occupy a significant proportion of the vessel if adequate bulk motion is to be achieved.

Natural frequency

First lateral vibrational frequency associated with an overhung shaft.  Primary factors include impeller weight, shaft length and diameter.  Other components, including the supports, also have natural frequencies and other modes of vibration are possible and may be important in special cases.

Newtonian Fluid

A fluid whose rate of flow is not proportional to the stress applied to it. The viscosity is independent of shear stress.

Non-Newtonian Fluid

A fluid whose rate of flow is proportional to the stress applied.  The viscosity may increase or decrease with stress, with time or with a combination of both. Also refer Pseudoplastic, Thixotropic, Dilatant, Viscoelastic.

Pumping capacity

A defined quantity used to characterize the amount of liquid motion provided by the operation of a mixing impeller.

Pseudoplastic

Non-newtonian type Shear thinning fluids.  With this of fluids, viscosity decreases with increasing shear rate. This is time independent.

Saybolt Seconds, Unieversal (SSU)

A method of reporting kinematic viscosity, most common in petroleum industry; 1000 centistokes equals 462 SSU.

Reynolds number

The ratio of inertial forces to the viscous forces for determining flow.

Rheology

It is the study of material flow behaviour.

Rheopectic Fluids

Time dependent Non-newtonian fluid. The apparent viscosity gradually builds up with time at constant shear rate.

Suspension

The action or result of combining a particulate solid and liquid, and providing sufficient motion to retain fluid characteristics

Turbulent mixing

Flow associated with low viscous liquids.  The inertial forces imparted to the fluid by the rotating impeller is sufficient to cause it to circulate throughout the vessel and back to the impeller again.

Thixotropic Liquids

Time dependent Non-newtonian fluid.  The apparent viscosity reduces with time as the material is sheared at a constant shear rate.

Viscoelastic Fluids

Non-newtonian fluid type and can exhibit elastic recovery. Behave in a part as a viscous liquid and part as an elastic solid.