A SYSTEM TO MEASURE VISCOSITIES OF SPRAY MIXTURES AT HIGH-SHEAR RATES

The viscosity of spray mixtures can greatly influence the sizes of spr ay droplets produced by atomizers. However, no low-cost system has bee n available to measure the viscosity at the high shear rates that are typical of pesticide mixtures passing through orifices of nozzles at p ressures commonly used in agricultural spraying. An inexpensive system was developed to measure viscosity at shear rates up to 200 000 s(-1) for both Newtonian and non-Newtonian liquids. Viscosity measurements of Newtonian liquids with viscosities ranging from 0.87 to 9.1 mPa s i ndicated that the measured viscosity was within 5% of the actual value at various high shear rates up to 200 000 s(-1). As shear rate was in creased, the viscosities of mixtures of water with drift control agent s 'Nalco-Trol,' 'Target' and an experimental formulation decreased rem ained about the same, and increased respectively.