Effect of adjuvants on the amount of air included in droplets generated by spray nozzles

Abstract

ABSTRACT:The air included in droplets generated by spray nozzles directly int0erferes in transport, deposition and retention of the droplets after its impact on the target. The objective of this study was to analyze the interference of adjuvants in the amount of air included in droplets generated by spray nozzles. The treatments were composed by four spray solutions containing mineral oil, vegetable oil, surfactant and water, and three spray nozzles, two air induction type and one pre-orifice. The air included was calculated by the difference between the volume of spray mix (air plus liquid) and only the liquid, which was made by means of sprayed samples captured in a funnel and collected in a graduated cylinder. The surface tension was estimated by the gravimetric method using a precision scale and a graduated pipette. The surfactant provided the largest percentage of air included in the spray. For the surface tension, the mineral oil and the surfactant had the lowest values. It was concluded that the use of adjuvants had a direct influence on the percentage of air included. In addition, products with greater ability to reduce surface tension and to form homogeneous solutions provided the increase in the percentage of air included in the droplet.KEYWORDS: application technology, air induction, pre-orifice, surface tension. INFLUÊNCIA DE ADJUVANTES NA QUANTIDADE DE AR INCLUÍDO EM GOTAS GERADAS POR PONTAS DE PULVERIZAÇÃORESUMO: O ar incluído em gotas geradas por pontas de pulverização interfere diretamente em seu transporte e deposição, influenciando também na retenção das mesmas após o impacto no alvo. O objetivo deste trabalho foi verificar a interferência de adjuvantes na quantidade de ar incluído em gotas geradas por pontas de pulverização. Os tratamentos utilizados corresponderam a soluções contendo: óleo mineral, óleo vegetal, surfatante e água, aplicados com três tipos de pontas de pulverização, sendo duas com indução de ar e uma com pré-orifício. O ar incluído foi calculado através da diferença entre o volume da mistura pulverizada (ar mais líquido) e apenas o líquido, que foi feito por meio de amostras pulverizadas, capturadas em um funil e coletadas em proveta graduada. A tensão superficial foi estimada através do método gravimétrico, utilizando uma balança de precisão e uma bureta graduada. O surfatante foi o que proporcionou maior porcentagem de ar incluído na pulverização. Para a tensão superficial, as caldas contendo óleo mineral e o surfatante tiveram os menores valores. Os resultados mostraram que o uso de adjuvantes tem influência direta na porcentagem de ar incluído. Além disso, adjuvantes com maior capacidade de redução da tensão superficial e que formam misturas mais homogêneas proporcionaram aumento da porcentagem de ar incluído nas gotas pulverizadas.PALAVRAS-CHAVE: tecnologia de aplicação, indução de ar, pré-orifício, tensão superficial.

Development and implementation of a laboratory spray device and rainfall simulator for retention research using small amounts of agroformulations

“…Among others, the effect of air inclusions in the droplets produced by the air‐induction nozzles in the rainfall simulator should be examined, as rain droplets do not have air inclusions. These air inclusions are known to modify droplet impact behaviour, such as rebound and shatter . With water alone, the proportion of air included in the spray is nevertheless very limited, even with air induction‐nozzles .…”

“…These air inclusions are known to modify droplet impact behaviour, such as rebound and shatter . With water alone, the proportion of air included in the spray is nevertheless very limited, even with air induction‐nozzles . Furthermore, water‐only droplets are assumed to lose their air inclusions by 0.2 m below the nozzle .…”

Application of rape pod sealants to reduce adverse environmental impacts

“…Data show that the addition of the surfactant delays drop breakup as a result of the decrease in average surface tension provided by the surfactant, thereby reducing the growth rate of an interfacial capillary wave . It has also been determined that the surfactant influences the amount of air that is added in the drops generated by spray nozzles . As a consequence of the different conditions of surface tension generated by the surfactant, a negative correlation between the surface tension and amount of air included has been observed, meaning that the lower the surface tension, the greater the percentage of air is included.…”

“…As a consequence of the different conditions of surface tension generated by the surfactant, a negative correlation between the surface tension and amount of air included has been observed, meaning that the lower the surface tension, the greater the percentage of air is included. Besides this, the composition of the surfactant affects these characteristics, and a water‐soluble surfactant is therefore more likely to increase the amount of air included in cases where the surfactant forms an emulsion …”

“…Besides this, the composition of the surfactant affects these characteristics, and a water-soluble surfactant is therefore more likely to increase the amount of air included in cases where the surfactant forms an emulsion. 37 The drift trial in the wind tunnel demonstrated that when 30 L of a PS solution was sprayed within 41.5 min, the solution did not end up in any containers located at a distance over 4 m. Nonetheless, the corrugated tin surface of the test bench was moist. Hence a distance of 4 m was chosen for the PS spray coverage trials.…”