Abstract: A disinfestation system for agricultural products, for example recovered tobacco, comprises a disinfestation unit which is releasably connected to plural containers. The disinfestation unit supplies a disinfestation gas (CO.sub.2) through the conduit means to the container, and periodically withdraws sample gas from said container. A thermal conductivity detector produces an electrical signal representation of the level of CO.sub.2 in the container, which is supplied, along with a temperature dependent signal, to a computer. The processor controls the introduction of additional CO.sub.2 throughout the process. Preferably, the system also includes heater elements, and the processor generates control signals for controlling temperature in the container. The computer controls the disinfestation process of multiple containers such multiple disinfestation processes can be carried out simultaneously.

Abstract: Tobacco is graded by size by separating a sample into size fractions using a rotary drum screen. The sample is characterized by two distribution curves, one for a finer portion and the other for a coarser portion. The crossing point of logarithmic plots of the percentage by weight vs. particle size distributions of the two portions provides a precise and sensitive descriptor, which can be termed as a "percent desirable fraction," for grading the size characteristics of threshed or cut tobacco.