Weight of raw wood. Specific weight of firewood. The weight of a cube of firewood depending on the type of wood

It varies over a wide range even for the same tree species. The values ​​​​of the density (specific gravity) of wood are generalized figures. The practical value of the wood density value differs from the given average table value and this is not an error.

Table of density (specific gravity) of wood
depending on the type of wood

• The table shows the density of wood at a moisture content of 12%.
• The figures in the table are taken from the Handbook of Aviation Material Masses, ed. "Engineering" Moscow 1975
• Updated on March 31, 2014, according to the method:
  Kolominova M.V., Physical properties wood: guidelines for students of the specialty 250401 "Forest Engineering", Ukhta: USTU, 2010
  Download (downloads: 382)

It is generally accepted to indicate the value of the density (specific gravity) of wood depending on the type of wood. The indicator is taken as the average value of the specific gravity, obtained by summarizing the results of multiple practical measurements. In fact, two tables of wood density are published here, taken from completely different sources. A small difference in indicators clearly indicates the variability of the density (specific gravity) of wood. Analyzing the values ​​of wood density from the above table, it is worth paying attention to the differences between the indicators of the aviation directory and the university manual. For objectivity, the value of the density of wood from both documents is given. With the reader's right to choose the priority of the importance of the primary source.

Of particular surprise is the tabular value of the density larches- 540-665 kg / m 3. Some Internet sources indicate the density of larch, equal to 1450 kg / m 3. Who to believe is not clear, which once again proves the uncertainty and unexploredness of the topic being raised. Larch is a fairly heavy material, but not so heavy that it sinks like a stone in water.

Influence of humidity on the specific gravity of wood

Specific Gravity of Driftwood

It is noteworthy that with an increase in the moisture content of wood, the dependence of the specific gravity of this material on the type of wood decreases. Specific gravity floating wood (humidity 75-85%) practically does not depend on the type of wood and is approximately 920-970 kg / m 3. This phenomenon is explained quite simply. The voids and pores in the wood are filled with water, the density (specific gravity) of which is much higher than the density of the displaced air. In its magnitude, the density of water approaches the density, the specific gravity of which practically does not depend on the type of wood. Thus, the specific gravity of pieces of wood soaked in water is less dependent on its species than in the case of dry samples. At this point, it is not superfluous to recall that for wood there is a division of classical physical concepts. (cm. )

Wood density groups

Conventionally, all tree species are divided into three groups
(according to the density of its wood, at a moisture content of 12%):

1. Rocks with low density(up to 540 kg / m3) - spruce, pine, fir, cedar, juniper, poplar, linden, willow, aspen, black and white alder, sowing chestnut, white walnut, gray and Manchurian, Amur velvet;
2. Breeds of medium density(550-740 kg / m3) - larch, yew, drooping birch, fluffy, black and yellow, oriental and European beech, elm, pear, summer oak, oriental, marsh, Mongolian, elm, elm, maple, hazel, walnut , plane tree, mountain ash, persimmon, apple tree, common ash and Manchurian;
3. breeds high density (750 kg / m3 and above) - white and sandy locust, iron birch, Caspian locust, white hickory, hornbeam, chestnut-leaved and Araksinsky oak, iron tree, boxwood, pistachio, hops.

The density of wood and its calorific value

The density (specific gravity) of wood is the main indicator of its heating energy value -. The relationship here is direct. The higher the density of the wood structure of a wood species, the more combustible woody substance it contains and the hotter these trees turn out.

The use of lumber in today's construction works ah, sorely needed. To determine the volume of these types of work, it is extremely important to correctly determine the specific gravity of the oak. Like all representatives of tree genera, oak does not have a constant specific gravity number, which complicates the selection process a bit. This is explained by given material is porous. Accordingly, the specific gravity of oak is measured based on the percentage of moisture.

From the foregoing, it follows that the main parameter when buying such building material, like oak, it is necessary to accurately know the moisture parameter. The highest moisture index has fresh, uncut trees, which have a moisture content of 30 to 80%. This is due to the fact that these trees are constantly replenished with vitamins and minerals from underground water depths, and water, in turn, is an extremely important conductor. Dried oak differs in the lowest indicator, as it has indicators tending to zero. The moisture index depends on the area, season of harvesting, as well as on the variety of oak.

The practical meaning and importance of the specific gravity of oak

Among the blanks of oak, wet, dry, dried and raw types are distinguished. However, the terms themselves do not give a clear idea of ​​the percentage of moisture, so it is extremely important to know the indicator is more or less accurate. This is also due to the fact that when performing construction work of certain types, the GOST standard for use is established. So, in the manufacture of products intended for placement in an open area, the norms provide from 11 to 14% humidity; in the manufacture of products for indoor use - from 8 to 10%; in the production of parquet - from 6 to 8%.

Weight table m3 of oak depending on humidity

It is extremely difficult to determine the percentage of such important parameter, as humidity, improvised means. These procedures are usually carried out in specially equipped laboratories.

It is very important, when buying material, to clarify the percentage of moisture. After that, using the table, it is easy to determine the weight of m3 of oak and the density of this material.

Go to alternative sources energy makes us pay attention to wood. It was it that our ancestors used to heat their homes and cook food. Furnaces, fireplaces, solid fuel boilers- for all these devices you need a tree, namely firewood. But all plants are different, and trees, having a different structure and chemical composition, differ in such characteristics as calorific value, weight, density, humidity.

How much does firewood weigh?

How to determine weight of 1 cube of firewood? Does it matter what kind of firewood you buy, fresh cut or dried? Knowing the specific gravity, moisture content and other features of wood will help to deal with this.

More than 200 species of trees and shrubs grow on the territory of our country. They all burn differently, some faster, others slower, some give off a lot of heat, and some less. When choosing a tree for a firebox, it is better to focus on a middle-aged tree, do not take too young or too old. They burn for the longest time and give off the most heat.

Also, the amount of heat given off directly depends on the density and dryness of the firewood. Wood with a moisture level of 15 - 20% is considered the most suitable for sending into the furnace, and in a freshly sawn tree, moisture is not less than 50%. Part of the heat will be spent on the evaporation of water, so the efficiency of wet firewood is much lower. Yes and dry wood weight much lower than wet ones.

The weight of wood depends on:

• structure of wood cells, their moisture content,
• wood density,
• parts of the plant (the heaviest parts are branches, the lightest are the base of the trunk),
• salt and resin content.

The weight of firewood can be determined empirically, that is, simply weigh a small piece of wood of a certain volume and, by simple calculations, find out its density (the ratio of mass in kilograms to volume in m3). But such a procedure is not convenient in all cases.

Tables of average wood weights will help make calculations easier. Conditional values ​​are given for the material moisture content of 15 - 20%. Interestingly, changing the moisture content of a tree does not change its density, although it greatly affects the value of the specific gravity.

What is the best firewood for fireboxes?

Oak firewood is considered the most optimal in terms of calorific value, followed by birch, aspen and pine.

• Oak contains few resins, but releases a lot carbon monoxide. The tart aroma of burning oak logs tones the body.
• Birch firewood burns for a long time, evenly, but has a lot of resinous substances and deposits soot in the chimney.
• conifers also used less frequently due to high resin content.
• It is not recommended to use poplar firewood, as it emits an unpleasant bitter odor and provides little heat.

Best use of firewood hardwood trees, the specific gravity of which is high. It is desirable that the firewood be dry, not freshly cut. Recall that when buying wet firewood, you pay more for the weight, but you get less heat.