Permitted working hours with a motorised backpack sprayer

Small-scale farmers often use motorised backpack sprayers to apply chemicals to crops. However, vibration from their internal combustion engines and other motive parts, such as pumps, is transmitted to the operator's body and this could cause harm. Vibration signals from a motorised backpack sprayer were measured using 3-axis accelerometers attached to the frame of the sprayer and the operator's wrist, chest, head and neck. The results from fast Fourier transform analysis showed a peak in horizontal vibrations of 3 m s−2 at a frequency of 20 Hz. According to ISO-2631-1 standard, this outcome signifies that the maximum continuous working time for practical use for the sprayer under test should therefore not exceed 1 h.