Catalog 50A_All_Low Res - TeeJet

Spray Distribution QualityOne of the most overlooked factors that candramatically influence the effectiveness ofa given crop production chemical is spraydistribution. The uniformity of the spraydistribution across the boom or within thespray swath is an essential component toachieving maximum chemical effectivenesswith minimal cost and minimal non-targetcontamination. This is more than critical ifcarrier and chemical rates are applied atthe recommended minimum rate. Thereare many other factors influencing a cropproduction chemical’s effectiveness, suchas weather, application timing, activeingredient rates, pest infestation, etc.However, an operator must become awareof spray distribution quality if maximumefficiency is expected.Measurement TechniquesSpray distribution can be measured indifferent ways. Spraying Systems Co.®, andsome sprayer manufacturers, as well asother research and testing stations, havepatternators (spray tables) that collectthe spray from nozzles on a standardizedor real boom. These patternators have anumber of channels aligned perpendicularto the nozzle spray. The channels carry thespray liquid into vessels for measuring andanalysis (see photo with TeeJet patternator).Under controlled conditions, very accuratedistribution measurements can be madefor nozzle evaluation and development.Distribution measurements can also takeplace on an actual farm sprayer. For staticmeasurements along the sprayer boom,a patternator equal or very similar to theone described earlier is placed underthe boom in a stationary position or as asmall patternator unit scanning the wholeboom up to a width of 50 m. Any systemof patternator measures electronicallythe quantity of water in each channeland calculates the values. A distributionquality test gives the applicator importantinformation about the state of the nozzleson the boom. When much more detailedinformation about spray quality andcoverage is required, a dynamic system—spraying a tracer (dye)—can be used. Thesame is true if the distribution within theswath on a boom has to be measured.Currently, only a few test units worldwidehave the ability to perform a stationarytest. These tests usually involve shaking ormoving the spray boom to simulate actualfield and application conditions.Most of the distribution measuring devicesresult in data points representing thesprayer’s boom swath uniformity. Thesedata points can be very revealing justthrough visual observation. However, forcomparison reasons, a statistical method iswidely accepted. This method is Coefficientof Variation (Cv). The Cv compiles all thepatternator data points and summarizesthem into a simple percentage, indicatingthe amount of variation within a givendistribution. For extremely uniformdistributions under accurate conditions, theCv can be ≤ 7%. In some European countries,nozzles must conform to very strict Cvspecifications, while other countries mayrequire the sprayer’s distribution to be testedfor uniformity every one or two years. Thesetypes of stipulations emphasize the greatimportance of distribution quality and itseffect on crop production effectiveness.Factors Affecting DistributionThere are a number of factors contributingto the distribution quality of a spray boomor resulting Cv percentage. During a staticmeasurement, the following factors cansignificantly affect the distribution.K Nozzles– type– pressure– spacing– spray angle– offset angle– spray pattern quality– flow rate– overlapK Boom HeightK Worn NozzlesK Pressure LossesK Plugged FiltersK Plugged NozzlesK Plumbing Factors Influencing LiquidTurbulence at NozzleAdditionally, in the field during the sprayingapplication or during a dynamic distributiontest, the following can influence thedistribution quality:K Boom Stability– vertical movement (pitch)– horizontal movement (yaw)K Environmental Conditions– wind velocity– wind directionK Pressure Losses (sprayer plumbing)K Sprayer Speed and Resulting TurbulenceThe effect of distribution uniformity on theefficiency of a crop production chemicalcan vary under different circumstances. Thecrop production chemical itself can havedramatic influence over its efficiency. Alwaysconsult the manu fac turer’s chemical label orrecommendation before spraying.180TECHNICAL INFORMATION