The Nuts and Bolts of Computerized Particle Analysis

A computerized particle analyzer (CPA) can be used in a variety of ways to determine counts and particle size measurements of a sample of many materials. The utility of this instrument to analyze an assortment of materials can directly correlate to its accuracy and precision. Accuracy and precision test were conducted on Tyler’s Computer Particle Analyzer 2. The CPA uses a conveyer system to throw objects between a 34 micron line scan camera and light source to determine particle parameters and analyze samples. Tall fescue seed samples of varying counts were used to determine the accuracy of the CPA. Counts of 100, 500, 1,000, and 5,000 were analyzed for total number of rejected particles (particles not fully captured) and touching particles. The mean accuracy for each sample size, 100, 500, 1,000, and 5,000, were 98%, 98.1%, 99%, and 98.5%, respectively. Precision of the CPA was tested using machined metal washers and nuts of known sizes. Overall, particles measured with the CPA varied ± 0.2 mm (5-6 pixels) from the actual particle sizes. This error could be attributed to the oscillation or twisting of the particle as it leaves the conveyor and crosses the scanning line. Objects with surfaces that are rounded and susceptible to roll could increase in the amount of error incurred during measurements. Given the minimal amount of error incurred in a sample’s count and particle dimension analysis, the computerized particle analyzer is one of the most accurate and precise instruments available for nondestructive particle analysis.