MIX SCALE – SCALE OF AGITATION

Mix Scale is used to quantify the mixing intensity needed for a given process as well as provide a frame of reference for mixing scale-up.

This 1-to-10 agitation scale is based on the impeller pumping capacity divided by the tank cross-sectional area, resulting in a bulk fluid velocity. This velocity, in feet/minute (ft/min.), then is divided by 6 to obtain the scale of agitation. This simple 1-to-10 scale has been used for decades as a valuable tool for quickly describing mixing intensity.

TYPE DESCRIPTION MIXSCALE TYPICAL APPLICATION

MILD

LITTLE SURFACE MOTION, NO SPLASH, MILD RIPPLE 1 MOST STORAGE APPLICATIONS.LOW VISCOSITY BLENDING OF LIQUIDS WITH MINIMAL DIFFERENCE IN SPG'S & VISCOSITY. VISCOSITY IN THE RANGE OF 100 CPS AND BELOW. LIGHT SOLIDS MOVING ON TANK BOTTOM, NO SUSPENSION.
2
3

MODERATE

SLOW ROLLING LIQUID SURFACE OCCASIONAL WAVE WITH LITTLE SPLASH 4 LOW TO MEDIUM VISCOSITY BLENDING WITH SP.G. DIFFERENCE LESS THAN 0.6 WITH VISCOSITIES GENERALLY BELOW 5000 CPS. SOLIDS MOVING OFF BOTTOM BUT NOT SUSPENDED ANYMORE THAN 20% THROUGHOUT TANK. EASY HEAT TRANSFER.
5
6

VIGOROUS

SOME SPLASH WITH BOILING ACTION AT SURFACE, OCCASIONAL VORTEX 7 MEDIUM VISCOSITY LIQUID/LIQUID BLENDING. SP.G. DIFFERENCE LESS THAN .85 WITH VISCOSITY LESS THAN 10,000 CPS. MODERATELY SUSPENDED SOLIDS THROUGHOUT 75% ON TANK. GOOD HEAT TRANSFER.
8

VIOLENT

SPLASHING AND LARGE WAVE FORMATIONS, ERRATIC VORTEXING 9 LIQUIDS WITH VISCOSITIES LESS THAN 25,000 CPS WITH SP.G. DIFFERENCE OF 1.0. SOLIDS SUSPENDED TO COMPLETE UNIFORMITY.
10