Specific gravity of firewood. Weight of a cube of firewood depending on the type of wood

The transition to alternative energy sources forces us to pay attention to wood. This is what our ancestors used to heat their homes and cook food. Stoves, fireplaces, solid fuel boilers - all these devices require wood, namely firewood. But all plants are different, and trees, having different structures and chemical compositions, differ in such characteristics as calorific value, weight, density, and humidity.

How many cubic meters of firewood are in a car trailer?

So, if the internal dimensions of the trailer

are: length - 2.05 m, width - 1.1 m, height 0.3 m, its cubic capacity will be equal to: 2.05 × 1.1 × 0.3 = 0.68 cubic meters.

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2021
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How much does firewood weigh?

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

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

Also, the amount of heat released 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 to the firebox, and in a freshly cut tree the moisture level is not less than 50%. Some of the heat will be spent on evaporation of water, so the efficiency of wet firewood is much lower. And the weight of dry firewood is significantly lower than wet firewood.

The weight of wood depends on:

• structure of wood cells, moisture content in them,
• wood density,
• parts of the plant (the heaviest parts are the branches, the lightest are the base of the trunk),
• content of salts and resins.

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

Tables of average wood weights will help make calculations simpler.
The values ​​are given conditionally for a material humidity of 15 – 20%. Interestingly, changing the moisture content of a tree does not change its density, although it greatly affects the specific gravity value. Table of some reference values ​​for wood density and weight of firewood during loading

Birch tree volume

The diameter of the tree was measured at 1.3 meters from the ground. The volume is calculated assuming that the tree is a solid mass and is measured in liters. Although the table shows birch, it provides a good guide for all trees with straight trunks.

Conclusions and comments

First of all, we wanted to test ourselves, because... Sometimes doubts arose about honesty towards our firewood buyers. Now the doubts are dispelled. Our stacking density and volume of firewood in stacked cubic meters meets the necessary requirements

.

If we turn again to the sawmill reference book (Note 1), it is obvious that the weight of 1 folded cube at a humidity of 50% will not always be 560.9 kg, because the weight of one dense cube is 790 kg - this is an average value and can range from 553 kg to 1027 kg. And, therefore, 1 stacker of birch chopped firewood (taking into account the coefficient of 0.71) can weigh from 392 kg to 729 kg. This is probably due to the different densities of trees and logs.

Of course, this experiment cannot be considered 100% objective, because At a minimum, a moisture meter is needed to determine humidity. Our forest may have different humidity levels because... There are many suppliers and the procurement and delivery times are different for everyone; accordingly, forest moisture can vary from 30 to 60%.

If you have any suggestions or comments on this material, please write to our email.

In order to transport birch firewood correctly, quickly and optimally for both the seller and the buyer, you need to know what the weight of the cube is and how much birch firewood is in a cubic meter.

The question is actually voluminous and debatable. Because firewood in dry and wet form is different. The age of the plant also affects the weight, because wood tends to accumulate mineral and organic substances. In addition, the density of the tree varies due to the presence of knots and cavities. And it depends heavily on the environment.

A few words about terms

A banal desire to find out how much firewood weighs actually turns into an interesting excursion into botany, geography, geometry and physics. Moreover, no one guarantees the accuracy of the calculation; the data will “walk” every day. Perhaps this is why sellers do not ask “how much to weigh in grams”, but suggest using the volume of wood instead of mass.

How much can a cube of firewood weigh and how to calculate it correctly? More details about everything below:

As you know from a physics course, mass (how much it weighs in kilograms/centners/tons) and weight (the force with which it is attracted to the Earth, measured in newtons) are different concepts, although in everyday life they have long become synonymous.

When talking about the weight of firewood, three points can be kept in mind:

• weight - exactly how many kilograms of wood fit into a cube in order to estimate the real cost of the product and whether the seller was deceived;
• the weight of a cube of stacked firewood - with what force the forest will press on the base of the machine, firewood stand, rack shelf, garage tiles, plank floor of the veranda, etc., when it is necessary to determine whether the building or structure will withstand such a load;
• the weight of the wood - how dense the structure is and how long it will take to dry, burn well and give off heat.

Most often, ordinary people talk about the weight of firewood, meaning mass. They are interested in how much birch chopped firewood weighs in kilograms. Such a substitution of concepts helps to avoid confusion in the dialogue between the seller and the buyer.

Number of kilowatts in 1 tree

For the calculation, firewood with 20% humidity was considered when burned in a stove with 75% efficiency.

How much firewood do you need for the winter?

On average, heating a house with an area of ​​100 m2 for one winter requires about 10 m3 of oak firewood. However, this figure may vary slightly depending on the insulation of the house and how cold the winter will be.

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What determines the mass of a tree?

The weight of firewood is a variable value and depends on many factors and conditions. First of all, it depends on the type of tree - birch is almost one and a half times heavier than poplar, which can be explained by different densities.

The main indicators are:

• the amount of impurities and substances in wood fiber (resin, salt, liquid);
• humidity

On a note! Dry birch firewood has a moisture content of 15%, while wet birch firewood has a moisture content of 50%, this is almost a 20% difference in the mass of one cubic meter!

• part of the tree - the branches are the heaviest, then the trunk, then the roots - they are the lightest.

The age of the tree and the method (density) of laying it in a cube also matter. The period and conditions of wood storage are taken into account in the humidity parameter.

Conclusion: the same volume of birch firewood will almost always weigh differently, but within the permissible error according to the reference book.

Important! The necessary tables and calculations are given in the sawmill handbook and GOST 3243-88!

Here is the key point - a cubic meter can be clean (according to the reference book), folded (evenly and tightly folded) and bulk. It is clear that the weight characteristics of the volume will be different. Depends on how even the split log is, the range is in cm of length.

Firewood carrier Vuoksa-Wood, linen

Volume of ash in wood

How many trees are needed to produce 12,000 kW

The table shows the number of trees required to produce 12,000 kW. Calculations assume 20% moisture when burning in a 75% efficient oven.

How much does a cubic meter of chopped firewood weigh?

The moisture content of firewood varies significantly. Wood can absorb water up to 100% of its volume. Thereby doubling the weight. Such wood not only burns somewhat worse, but also pricks disgustingly. And of course it is inappropriate to transport it.

Comparison of wood firewood by moisture content:

• Wet or 100% humidity - long stay in water;
• Fresh 60-90% humidity - freshly cut wood;
• Dry and semi-dry from 20 to 8% long stay in a heated room;
• Exceptional dryness, 0% humidity - drying at a temperature of 103 degrees.

The following is considered to be a criterion for the moisture or dryness of firewood:

Up to 23% of the firewood is damp, from 14% of the firewood is dry. All this is very conditional. And in each specific case, individual conditions must be taken into account.

Counting chopped firewood by volume is not very convenient, due to the large number of air cavities and uneven stacking. Which significantly increases the volume of firewood. But a special formula for a folded cube has been developed, which can be used to count a woodpile and find out its volume and weight.

It looks like this:

The width of the woodpile, multiplied by the length, multiplied by the height, multiplied by 0.7. You will get the true volume of cubic meters.

To derive weight from cubic meters, the most important thing is to know the humidity:

• Freshly cut birch 870 kilograms per cubic meter;
• Birch dried by 50% - 790 kilograms;
• Almost dry wood 15% humidity - 640 kilograms.

The most popular and optimal vehicle for transporting firewood is the Gazelle. And therefore it is important to know the next paragraph.

Experiment: weigh 1 cube of firewood.

The Drova72 company conducted an experiment, we weighed 1 folding cube (storage meter) of birch chopped firewood, natural humidity,

50%. We will discuss the results of this experiment in more detail below.

This experiment in no way claims to be “scientific” or “100% objective”

, rather something between information from the Internet and laboratory research. But nevertheless, this is the first step on the path to truth and objectivity.

Weight of different tree species

We weigh

To begin with, we placed 1 cubic meter of birch firewood in a woodpile, just like we deliver it to our customers.

In the photo below, the volume that we will measure is outlined in red. On the left and right, we used the bagged firewood as a support so that our woodpile would not fall apart while we were measuring it.

Next, we take measurements to make sure that there is at least one stacked cubic meter of firewood in our woodpile.

The length and height of the woodpile are approximately the same, but there are discrepancies in the length of the logs due to hand sawing and splitting. The length of the logs varies from 42 to 48 cm, sometimes up to 52 cm, much more often in the range of 45-48 cm. After measuring several times, we get an average length of 45 cm.

Woodpile length 206cm, height 110cm. We calculated the length and height of the woodpile according to the minimum values. For example, the height of the woodpile turned out to have a slight difference, from 115 to 110 cm. Next, we convert the numbers into meters and multiply.

How and with what will we weigh?

To weigh our volume of firewood, we decided to put the firewood into bags and weigh them with ordinary scales. Then, add up the weight of each bag and get the total weight of 1 folding cube.

Add and get the result

As a result, we got 25 bags of firewood, the average weight of each bag

23 kg. And the total weight is 566.5 kg. Those. even a little more than we originally should have received.