Question

A tractor operated sprayer has 24 nozzles spaced 50 cm apart. Time lost in turning is 8% and filling the tank takes 7% of the time. If the sprayer is operated at a speed of 5 km/h, calculate the coverage area in ha per hour.

• A. 2.6
• B. 3.0
• C. 5.1
• D. 6.0

Hint:

First get the theoretical area covered per hour from swath width and speed, then reduce it by the total time lost.

Answer 1

The Correct Option is C

Step 1: Find the effective swath (working) width of the sprayer boom. There are 24 nozzles spaced 50 cm apart, so the width covered is \(24 \times 0.50 = 12\) m.

Step 2: Calculate the theoretical field capacity using the standard relation for area covered per hour, \(\text{TFC (ha/h)} = \dfrac{\text{width (m)} \times \text{speed (km/h)}}{10}\). Substituting, \(\text{TFC} = \dfrac{12 \times 5}{10} = 6\) ha/h.

Step 3: Work out the field efficiency. Time is lost in two ways here, turning at the ends of the field (8%) and stopping to refill the tank (7%). Total time lost = 8% + 7% = 15%, so the field efficiency is \(100\% - 15\% = 85\% = 0.85\).

Step 4: Multiply the theoretical field capacity by the field efficiency to get the effective (actual) field capacity: \(6 \times 0.85 = 5.1\) ha/h.

Step 5: Option 1 (2.6) and option 2 (3.0) are too low, they would result from wrongly halving the width or speed. Option 4 (6.0) ignores the time lost in turning and refilling altogether. The correct coverage area, after accounting for lost time, is 5.1 ha/h.