You should replace a used nozzle when its flow rate varies _________ percent or more from a new nozzle.

Replacing a used nozzle when its flow rate varies 5 percent or more from a new nozzle is crucial for maintaining the effectiveness and accuracy of pesticide application. Over time, nozzles can wear down due to factors such as chemical exposure, physical abrasion, and buildup of deposits. This deterioration can lead to uneven spray patterns and variations in flow rates, which can affect pesticide distribution and efficacy.

By setting the threshold at 5 percent, applicators can ensure that the equipment they use delivers a consistent and precise volume of pesticide. This is especially important in structural pest control, where adequate coverage is necessary to achieve desired pest management outcomes. A nozzle that performs outside this range may not apply the correct amount of pesticide, potentially leading to under-treatment of an infestation or excessive application, which could pose environmental and safety risks.

Choosing a higher percentage, such as 10 percent or more, could lead to significant discrepancies in application rates that might compromise pest control efforts. Therefore, adhering to the 5 percent variation guideline helps ensure optimal performance of spraying equipment and promotes responsible pesticide application practices.