Statistical Aspects of Sampling Sprays

Abstract

Sampling sprays and spray deposits actually means collecting a large but finite number of drops of various sizes. Therefore, statistically, averaged spray volume and standard deviation are based on a binomial distribution. If sample size is too small, not only the coefficient of variation will be large, but also the average drop size in the sample will be biased towards smaller drops. Typically, 104 drops are required for determining a stable drop size spectrum of a conventional nozzle with an accuracy (CV) of 2.5%. Given a required accuracy for spray deposits, the minimal target area can be derived.