Assessment of commercial in-line meters for measuring the moisture content of radiata pine lumber
2001
Simpson, I. | Haslett, T.
Four commercially available in-line moisture meters were assessed using 40-mm and 50-mm-thick Pinus radiata (radiata pine). Linear regression models were developed between the meter readings and the moisture content (MC) determined by ovendrying, and confidence intervals (CI) were determined to quantify the accuracy of the predicted actual MC. The CIs varied with MC, and surprisingly, the CI for the Lignomat and the Moisture Register Products meters decreased with increasing MC. The Elliott Bay meter predicted MC most accurately at MCs below 14 percent with its accuracy decreasing above 14 percent MC. The Lignomat meter gave the most accurate MC prediction above 14 percent. The Moisture Register Products meter was the least accurate of the meters over the range of 6 to 20 percent MC. The Wagner 683 meter had acceptable accuracy over the range of actual MC from 5 to 20 percent. Density had no effect on the Elliott Bay meter, which uses a resistance principle for determining MC. Density had a significant effect on all other meters, with the Lignomat being the least affected of the three non-resistance-type meters. However, the effect of density is considered to be insufficient to effect commercial use. Provided appropriate meter corrections are used and the meters are periodically calibrated, all four in-line meters should be acceptable for segregating unacceptably wet lumber from lumber of acceptable MC for remanufacturing uses.
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