Ergonomic studies on power operated knapsack sprayer

The ergonomic studies were carried out on agricultural workers performing spraying operation by power knapsack sprayer. Ergonomic evaluation of machines with respect to physiological parameters like heart-rate, body discomfort, postural configuration and vibrations had been carried out. The independent parameters selected were three subjects of different age groups and three engine rpm (4000, 5000 and 6000) for the machine. The heart rate varied from 96 to 117 bpm, overall discomfort rating between 2.83 and 4.50 and postural configuration between 2.67 and 9.67 while operating the sprayers. Noise at operator's ear in stationary mode while operating the machine also increased with increase in engine speed and the increase was by 18.5% when engine speed increased from 4000 to 6000 rpm. The safe exposer limit was 7 h and 3.8 h per day, respectively for engine speeds of 5000 and 6000 rpm. The acceleration decreased for all the subjects when engine speed increased from 4000 to 6000 rpm. When rpm of the sprayer was increased to 5000 rpm from 4000 rpm the vibration on exhaust and engine increased to two fold and on insecticide tank it increased to three fold under stationary conditions. Further increase in speed from 5000 to 6000 rpm the vibration on exhaust increased 1.69 fold and on engine top 1.53 fold. It can be concluded from the experiments that power knapsack sprayer should be operated at 5000 rpm continuously for 12 lit spray.