What is the humidity standard for wood?
Drying method:
Drying method is the temperature of the wood to test the film to the whole dry to measure the water content of the method.
First in the measured wood saw a section thickness of 10 ~ 12mm representative of the water content of the test piece. The so-called representative is the piece of dry and wet pieces of the same piece of wood consistent with, and no folder skin, knots, decay, insects and other defects. Generally should be at the distance from the edge of the saw blade 250 ~ 300mm interception. After the water content of the test piece scraping the burr and sawdust, should immediately in the accuracy of 0.01g, range of not less than 200g on the balance of its weight, the weight of G, and then put the test piece into the temperature of 103 ± 2 ℃ in the incubator bake about 6h, and then remove the weighing, and for recording, and then back into the oven to continue drying. Then every 2h weighing once, until the last two weighing the same weight, that is dry weight, recorded as Go. So that the moisture content can be calculated as follows:
W = (G-Go) / Go × 100%
As the thin test piece exposed to air in the water is easy to change, so the measurement should pay attention to intercept the test piece or remove the oven should be immediately weighed, if not immediately weighed, must be immediately packaged with plastic bags to prevent water evaporation.
The moisture content of the wood is measured accurately by the drying method and is not limited by the water content range. But the measurement needs to intercept the sample, destroy the wood, and take some time.
Drying method is the basic method of measuring the moisture content of wood, but also the most commonly used method. The above formula is the absolute moisture content, but also in the wood processing is usually referred to the wood moisture content.
Not called humidity, but called the wood moisture content.
Under normal conditions of wood and its products, there will be a certain amount of water. China's wood moisture content and the weight of dry wood after the percentage of weight, defined as the wood moisture content.
The moisture content can be calculated using the weight of the whole dry wood, and the calculated value is called the absolute moisture content and is referred to as the moisture content (W,%). Calculation formula:
W = (Gs - Ggo) / Ggo × 100%
Where: W - wood absolute moisture content;
Gs - wet wood weight;
Ggo - dry weight.
Moisture content in laboratory measurements:
Methods for measuring the moisture content of wood are drying method, electric measurement method, dry distillation method, titration method and humidity method. In the field of wood processing, drying method is usually used.
