The performance of specially-built gas nozzles for thermal weed control

Abstract

The aim of this study was to develop a gas nozzle that can be used more appropriately in flame weeding compared to commercial ones. For this purpose, three different types of nozzles were built, tested at gas pressures of 1.0-3.0 bar, and flowrate-pressure characteristics were determined using gravimetric method. Among the gas nozzles built, 3-hole 1 mm diameter nozzle (Type1) was found to be appropriate to provide targeted LPG gas doses of 40-130 kg ha(-1) at a pressure range of 1.5-2.5 bar. This nozzle decreased the high ground speeds for low gas doses that had to be applied using the commercial gas nozzle, and increased the low ground speeds for high gas doses. As a result, the required ground speed range of 1.8-8.1 km h(-1) for the commercial nozzle was improved to 3.5-6.5 km h(-1) at an operating gas pressure of 2.0 bar. Field capacity can be increased using the specially-built nozzle since ground speeds were increased at high doses. Also, the exposure time of weeds to heat was increased about 20% at low doses, potentially increasing the flaming efficiency. Due to small hole diameters, Type2 and Type3 were not appropriate for tractor-mounted flame weeders. It was concluded that the result of the study to develop specially-built gas nozzle (Type1) as an alternative to commercial ones was positive.