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Title: UPDATE ON THE EFFECT OF CHANGES IN HUMIDITY ON HVI TESTING

Author
item Thibodeaux, Devron
item Rodgers Iii, James
item MARTIN, VIKKI - COTTON INC.
item WATSON, MICHAEL - COTTON INC.
item Delhom, Christopher - Chris

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 2/1/2007
Publication Date: 6/1/2007
Citation: Thibodeaux, D.P., Rodgers Iii, J.E., Martin, V., Watson, M., Delhom, C.D. 2007. Update on the effect of changes in humidity on hvi testing. National Cotton Council Beltwide Cotton Conference. 1206.

Interpretive Summary: Work continues on our study to determine the effects of changing testing environment on HVI measurements. Tests were conducted in the enviromental control room at the Cotton Quality Research Station in Clemson, SC. A set of 25 cottons representing both U. S. and international growths was preconditioned (dried at 60 deg. C for 24 hours) and was tested at 70 deg. F at relative humidities over a range of 45%RH and 85% RH. Results are reported on: a)the rate of change of length and strength with RH;b) the effects of introducing samples that have been pre-conditioned from the "dry side"; and c) the accuracy and efficiency of the Chinese Moisture Meter(Y412B).

Technical Abstract: The objectives of this study were to: a) determine the effect of changes in environmental conditions (deg F and % RH) on HVI measurements over a wide range of environments with a diverse set of test cottons; b) demonstrate the benefits of preconditioning samples so as to allow equilibrating to atmospheric conditions "from the dry side "; and c) test the accuracy and efficiency of the Chinese Moisture Meter (Y412B). We found that when the samples were not preconditioned they demonstrated a rather large range of slopes and offsets for the linear relationship of HVI strength with moisture content. Preconditioning the samples so that they all were introduced into the conditioned laboratory in the "dry" state significantly improved the correlation of strength with moisture content and narrowed the ranges of slopes and intercepts that might make a universal correction feasible. In addition the Chinese moisture meter, operating on the basis of conductivity, has a decent correlation (R2 = 0.80) with gravimetric moisture measurement for samples that were not introduced in the "dry" state. For pre-conditioned samples, the Chinese instrument performs much better (R2 = 0.93).