Replace nozzle when the discharge rate varies more than _________________ from the average discharge rate.

• A. 10%
• B. 20%
• C. 30%
• D. 40%

Answer: (B)

Uniform spray relies on every nozzle delivering nearly the same discharge as the others. When a nozzle wears, clogs, or is damaged, its flow can change, which means some areas would get more chemical and others less. To keep the overall application within the labeled rate and ensure even coverage, a practical rule is to replace a nozzle if its discharge rate varies more than 20% from the average of all nozzles. You’d test this by measuring each nozzle’s flow at the operating pressure and comparing it to the average; any nozzle outside the 20% window should be replaced. A smaller limit like 10% would be overly strict and cause unnecessary replacements, while larger limits like 30% or 40% would let too much variation slip through, risking under- or over-application and potential crop damage. Replacing worn or damaged nozzles helps restore a uniform spray pattern and keeps you within the label rate.