Absolute moisture sensing for cotton bales

Authors: Pelletier, Mathew

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Abstract Only
Publication Acceptance Date: 1/3/2006
Publication Date: 1/3/2006
Citation: Pelletier, M.G. 2006. Absolute moisture sensing for cotton bales. National Cotton Council Beltwide Cotton Conference. pp. 593-601.

Interpretive Summary:

Technical Abstract: With the recent prevalence of moisture restoration systems in cotton gins, more and more gins are putting moisture back into the bales immediately before the packaging operation. There are two main reasons for this recent trend, the first is that it has been found that added moisture at the bale press significantly reduces the packing force and thus reduces wear and tear. The second reason for this trend lies in cotton’s marketing on a wet basis, which provides a direct economic stimulus to add moisture back into the bale. This trend however needs to be tempered as recent research has shown that excess moisture in the bales will cause fiber degradation. This need has prompted the U.S. National Cotton Council to make a recommendation for bales to be limited to less than 7.5% moisture. This need has also led to the Mississippi Cotton Exchange to place a new ruling on acceptable bales for trade, the requirement to have less than 7.5% moisture. Thus, there is now a need for an absolute moisture sensing system that can be economically deployed into commercial cotton gins. In any absolute measurement system, there is a critical need for rapid calibration and verification of the accuracy of the sensor. The research of this study investigated methods for determination of the accuracy of through-transmission microwave sensors for quantitative analysis as well as rapid field deployable methods for in-field calibration and verification of the sensors accuracy in use. The results of the study led to the identification of suitable standards that are traceable to the U.S. NIST Laboratories. Thus, these standards can provide accurate and repeatable calibration benchmarks for both laboratory and in-field use. Utilizing these standards (NIST traceable permittivity standards), tests were conducted, utilizing the free-space microwave through-transmission technique, and found the expected accuracy for commercially deployed microwave sensors to have the potential of measuring moisture contents to +/- 0.1% moisture with a 95% confidence, r2=0.998.