Charring Rate of Selected Woods--Transverse to Grain

摘要

A study was designed to determine the charring rates for wood normal to the grain, and to evaluate the effect of fire intensity, species, specific gravity, moisture content, and annual ring orientation on these rates. Other material variables studied were the springwood to summerwood ratio and volatile extractive content. The effect of variation in moisture permeability, however, was not evaluated. Laminated wood slabs, 3 inches thick, of Douglas-fir, southern pine, and white oak were vertically exposed to fire on one surface. The rate of char development was constant when the specimens were exposed to uniformly increasing fire temperatures; charring rates at three constant fire exposure temperatures were described by a pseudo-first-order reaction equation with an Arrhenius temperature-dependent rate constant. Rates of char development in each species were related to the specific gravity and moisture content of the wood. The other material characteristics considered were directly related to specific gravity and moisture content or had no significant effect on the charring rate. (Author)