Some countries even have two or more methods. At present, the main imported log inspection methods and measurement units commonly used are as follows:
1) The International System of Units is used to measure meters (m), centimeters (cm) and cubic meters (m3).
(1) Timber length measurement: The length of the log is measured at the shortest distance between the two ends of the large and small heads.
(2) diameter measurement: through the center of the small head section, first measure the short diameter, and then through the center of the short diameter to measure the long diameter vertically (as if to take the maximum and minimum value through the center of the tree, not necessarily vertical), without skin measurement, such as the short diameter is less than 26cm, the difference between the length and short diameter is more than 2cm or the short diameter is more than 26cm, and the difference between the length and short diameter is more than 4cm, with the average of its length and short diameter, after the rounding for the ruler diameter. If the difference between the length and the short diameter is less than the above provisions, the short diameter shall be used as the inspection diameter after the short diameter is entered (see GB144-95 "Log Inspection, Size Inspection").
(3) Volume calculation:
A) The volume of log from 4~12cm is determined by the formula V=0.7854L(D+0.45L+0.2) 2 ÷10000;
B) The volume of log with a diameter of more than 14cm is determined by the formula V=0.7854L〔D+0.5L+0.005L2 +0.000125L· (14-L)· (D-10)] 2 ÷ 10,000 OK.
Where: V-volume(m3); L-ruler length (m); D-ruler diameter (cm). See GB4814-84 "Log Volume Table".
This method is applicable to the export and some of the logs specified in the import contract.
2) In imperial units, the units of measurement are feet, inches, and board feet.
(1) Timber length inspection: Measurement on the shortest side of the cross-section at both ends of the log. When one or both ends of a log are broken or damaged, the nearest two points should be taken at one or both ends that show the diameter of the log. See the Official Rules for Measuring and Rating Logs in the United States (January 1, 1982) ;
(2) Diameter Measurement: The diameter of the log passes through the center of the section with the small head, crosses each other perpendicularly, and the average of the long diameter and the short diameter is measured as the ruler diameter, without skin measurement. See the U.S. OFFICIAL RULES FOR THE GRADING AND GRADING OF LOGS (1 JANUARY 1982) ;
(3) VOLUME CALCULATIONS: USING THE SCRIBNER VOLUME TABLE OF THE UNITED STATES (REVISED JULY 1, 1972).
Volume calculation formula: V=A×L÷12 in/ft°
Where: V-volume (board feet): A - area (square inches) of the plate figure drawn in the small head section; L-Length (ft) and 12 in/ft-Conversion factor. This method is suitable for importing logs from the United States and Canada.
