Subtopic: Functional requirements, principles of working, construction and operation of manual, animal, tractor and renewable energy operated equipment for tillage, sowing, planting, fertilizer application, inter-cultivation, spraying, mowing, chaff cutting, harvesting and threshing
Question Statement:
Which of the following statements regarding droplet spectrum characteristics and atomization kinetics in agricultural spraying is/are CORRECT?
Options:
(A) Volume Median Diameter (VMD or $D_{v0.5}$) is the droplet diameter such that $50\%$ of the total spray volume is in droplets smaller than this value
(B) The Relative Span Factor ($RSF$) is defined as $\frac{D_{v0.9} - D_{v0.1}}{D_{v0.5}}$, where a lower value indicates a more uniform droplet spectrum
(C) Droplets having diameters smaller than $100\,\mu\text{m}$ are highly susceptible to wind drift and evaporative loss
(D) Operating hydraulic nozzles at higher liquid pressure significantly increases VMD and reduces spray drift
Answer Key:
A, B, C
Step-by-Step Solution & Explanation
- **Statement A is correct:** VMD ($D_{v0.5}$) divides the total liquid volume into two equal halves.
- **Statement B is correct:** $RSF$ measures the relative width of the droplet size distribution; a monodisperse spray has $RSF = 0$.
- **Statement C is correct:** Droplets under $100\,\mu\text{m}$ have negligible terminal settling velocity and drift extensively.
- **Statement D is incorrect:** Increasing hydraulic pressure increases liquid exit velocity and shear disintegration, producing smaller droplets (DECREASING VMD) and INCREASING drift risk.