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ARS Home » Midwest Area » Wooster, Ohio » Application Technology Research » Research » Publications at this Location » Publication #38262
Title: A SYSTEM TO MEASURE VISCOSITIES OF SPRAY MIXTURES AT HIGH SHEAR RATES

Author
item Reichard, Donald
item ZHU HEPING - OSU/OARDC-AGRIC ENGR DEPT

Submitted to: Pesticide Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/31/1995
Publication Date: N/A
Citation: N/A

Interpretive Summary: About 1.1 billion pounds of active ingredient of conventional pesticides are used annually in the U.S., and most is applied through nozzles. Both the efficiency of pest control and amount of spray drift depend on spray droplet size, and this is greatly influenced by viscosity of the mixture when it passes through the nozzle orifice. No low cost system has been available to measure viscosities at high shear rates typical of when liquids pass through orifices to form droplets. A low cost system was developed to measure viscosities of spray mixtures at high shear rates representative of spraying pesticides. Measurements of viscosity standards indicated that the system accurately measured viscosities over a wide range of viscosities. Measurements of viscosities of mixtures containing drift control agents showed that some have greatly different viscosities at high than at low shear rates. The system enables measurements of viscosities that indicate if various materials, and concentrations, would alter spray droplet size as desired, and may be useful in development of equations to predict spray droplet size from values of physical properties of spray mixtures.

Technical Abstract: The viscosity of spray mixtures can greatly influence spray droplet sizes produced by atomizers. However, no low cost system has been available to measure the viscosity at high shear rates that are typical of pesticide mixtures passing through orifices of nozzles at pressures commonly used in agricultural spraying. An inexpensive system was developed to measure viscosity at shear rates up to 200,000/sec for both Newtonian and non-Newtonian liquids. Viscosity measurements of Newtonian liquids with viscosities ranging from 0.87 to 9.1 mPas indicated that the measured viscosity was within 5% of the actual value at various high shear rates up to 200,000/ sec. As shear rate was increased, the viscosities of mixtures of water with drift control agents Nalco-Trol, Target and an experimental formulation decreased, remained about the same, and increased respectively.