Accurate Technology Pro-60 Manuale d'uso - Pagina 7

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SPECIES CORRECTIONS

The dry specific gravity (density) values for a species are based on the best, current

world data, and are used to determine the species correction factor within the meter.

The values provide average density values for the species. A coefficient of variation

(COV) of about 10% describes the variability inherent in many common domestic (US)

species.

If the specific gravity of your lumber is not listed in the Species Settings Tables

provided or you are dealing with an unknown species, the value may be determined by

referring to the "Determining the Specific Gravity" section of this manual. Additional

resources are: the Forest Products Lab at http://www.fpl.fs.fed.us/ and the Wood

Handbook at:

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/fplgtr113.htm

The Pro-60 meter can be used to measure non-wood materials if the density is similar

to wood products. Non-wood species can be measured by using the meter reading as

a relative value such as in "go/no-go" applications, or when determining if one

measurement area contains more moisture than another, i.e. measurements that do

not require a high absolute accuracy. SG formulas can't be applied to non-solid wood

species due to the presence of glues and resins, which cause a non-linear moisture

content curve. If greater accuracy is required, the ASTM oven-dry procedure can be

used to determine a meter correction value for non-solid woods.

Commentary on Species Adjustment

In 1992, a study was conducted at the Forest Research Laboratory of Oregon State

University on species correction for the Wagner Hand-Held Moisture Meters. The

species tested were Douglas Fir, Lodgepole Pine, Western Red Cedar, Western

Hemlock, White Fir, Western Larch, Engelmann Spruce, and White Oak. Three to four

40-piece samples of each species were tested. Specific gravity was found to be the

primary factor on species adjustment. A species equation as a function of specific

gravity and the meter reading was obtained using multiple-regression technique (R-

square = 0.95) as follows:

AF = 8.77 + (0.25 * MM) – (15.86 * SG) – (0.62 * SG * MM) in which

AF = Species Adjustment

MM = Meter Reading

SG = Specific Gravity in oven dry weight and 12% moisture-content volume basis.

The species adjustments provide the adjusted moisture measurements that are based

on the species adjustment determined using the species adjustment equation, with

rounding to the nearest 0.5.

Accurate Technology Pro-60

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