Influence of nozzle type and size on drift potential by means of different wind tunnel evaluation methods

46 Wind tunnel measurements were used to measure airborne and fallout spray volumes for 10 different spray nozzles. Drift potential reduction percentages (DPRPs), expressing the reduction of the drift potential compared with the reference spraying, were calculated using the following three different approaches: DPRPV1 was based on calculating the first moment of the airborne spray profile, DPRPV2 integrating the airborne spray profile, and DPRPH integrating the fallout deposit curve. The results showed the expected fallout and airborne spray profiles. For the standard flat-fan nozzles, DPRPV1 values were the highest followed by DPRPV2 and DPRPH. For the low-drift nozzles the opposite trend was found. The larger the ISO nozzle size, the greater the DPRP values for both these nozzle types. For the air-inclusion nozzles, there was close agreement between DPRPV1, DPRPV2 and DPRPH values. This is important in the interpretation of wind tunnel data for different nozzle types and sampling methodologies.