CPA Vs. Rotap: Granulometric Analytical Comparison

Tyler’s Computerized Particle Analyzer 2 (CPA) uses line scan imaging software to count and analyze particles of a given sample. Each image is grouped together and analyzed using software to separate the materials in personalized size classes. Similarly, traditional particle size distribution analysis using a Rotap separates a material by sieve sizes to yield a percent of the total mass captured in each sieve. In order to compare granulometric analysis from the two machines on a sample, five different horticultural sand sources were acquired for analysis. To accurately compare the CPA with the Rotap, the same 12 sieve sizes (or size classes) were used to analyze each sample. Using the size definition Minimum Feret and comparing the percent calculated volume of each size class within each sample, the data obtained from the CPA (percent of total volume per size class) were able to be compared to the data obtained from the Rotap (percent of total mass per sieve size) due to the consistency of sand particle density. Percent of sample lost in each method was also recorded. Using a volume model, the CPA was successfully able to identify similar trends in particle size distribution with half of the sample size necessary for the Rotap, 50 g as compared to 100 g. Sample loss during Rotap and CPA analysis ranged from 0.3-2% and 0.04-0.3%, respectively. Utilizing the CPA for granulometric analysis can effectively reduce sample loss and increase efficiency while providing many additional opportunities for analytical comparisons between samples.