Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 23, 1999
Publication Date: N/A
Interpretive Summary: Applying spray uniformly over a field is the first step in effective pest control. The most basic requirement for uniform application is maintaining a uniform spray mixture in the sprayer tank. Some pest control products, especially dry formulations, tend to float or sink to the bottom of the tank and require constant agitation to maintain a uniform mixture. Most commercial sprayers use hydraulic mixing, i.e., some of the liquid mixture from the pump is directed back into the bottom of the sprayer tank, usually through an agitating nozzle, to achieve the required mixing. Tests have shown that some sprayers have a significant increase in formulation concentration as the last 10% of the tank capacity is sprayed. This paper presents a unique procedure to measure and calculate an agitation effectiveness index (AFEF) which quantifies the mixing efficiency of a sprayer. This is the first time such an index has been used to rate the mixing effectiveness of sprayer agitation systems. The AGEF does not depend on tank size or shape or mixture concentration. Examples of measured tank mixture concentration during the entire time required to spray all of the mixture in the tank are shown. Significant differences in measured AGEF values were found among several agitation systems on a test sprayer. This procedure should be useful for sprayer manufacturers who want to test the agitation effectiveness of their sprayers.
Technical Abstract: An agitation effectiveness index (AGEF) was defined to help evaluate the effectiveness of hydraulic agitation systems in agricultural sprayer tanks regardless of tank size and shape. AGEF was calculated based on three measured mixing criteria: particle deposits remaining on the bottom of the tank following the application, the coefficient of variation of the mixture concentration in the line to the boom, and the ratio of maximum deviation of the mixture concentration at the tank outlet to the mean concentration measured during the application. The concentration of simulated wettable powder pesticides during an application was evaluated by employing a surface scatter type turbidimeter. The results showed that AGEF was sensitive enough to enable reasonable comparisons and that this method can be used to standardize minimum requirements of a hydraulic jet agitation system. The ratio of AGEF to required hydraulic power of the agitation system was also used as another parameter to evaluate sprayer tank agitation systems. AGEF and the power ratio provided a novel approach to identify efficient agitation systems with low energy requirements.