What is wood? This consisting of hydrophilic components material having a capillary-porous structure, and therefore it constantly contains a certain amount of water. If we consider a living tree, then here the water is needed to maintain his life, as it plays the main role, as in the human body. The amount of water contained in the tree is called humidity level. And in fact, this is one of the main and most important characteristics of the tree.

The humidity indicator is directly related to the quality of the material, has a great influence on its properties and, accordingly, on its suitability for use in certain construction work.

The level of humidity is indicated in percent, and is the ratio of the mass of water in the wood, to its dry mass.

Humidity also has the effects and interaction of material with water with rather significant characteristics, especially for processing mechanical or chemical path, for example, painting, impregnation with solutions, alloy and storage, etc.

The wood has a large content of cellulose, and water affects its activation. With this interaction, paper is made. At first, the tree smears mixing with water, and after the molding, water is removed, due to this, strong inter-ray bonds are formed in the finished material.

Also, the properties of wood directly determine the properties of products from it. When using such a material, it is necessary to select wood based on the humidity of air indoors, since it has a property to adapt to the microclimate of the room. Thus, with a lack of moisture, it will absorb her from the air and swell, with its overall, the opposite to dry. After the selection of wood and its installation, it is necessary to constantly maintain the humidity and temperature regime of the room.

Wood moisture is divided into 2 types:

1. Relative
2. Absolute

Relative humidity is determined in the percentage ratio of the mass of water to the mass of the entire material.

The absolute humidity is the relationship in the water tree to the dry mass of the wood itself, the relationship is also expressed as a percentage. On the example of the parquet, absolute humidity should vary from 6 to 12%, for the maximum manifestation of its operational abilities, this indicator should be 9%.

The concept of absolutely dry wood implies material dried to a constant mass at a temperature of from 102 to 106 degrees Celsius. In this case, the values \u200b\u200bof relative humidity are also needed, they are used in calculating the mass fraction of the components of the material in percentage ratio to absolutely dry material. This type of humidity is used to characterize wood samples when comparing them with respect to the water content.

Wood moisture degrees

1. Wet. The humidity of such a material exceeds the figure of 100% (this may be, if the wood has been in water for a long time).
2. Fresed. Humidity of such wood varies in the range from 50 to 100%.
3. Air dry. Wood dried naturally. The humidity of such a material may vary from 15 to 20 percent, depending on the climatic conditions and the time of the year, respectively.
4. Indoor dry. Such wood is also dried by naturally, but in a dry room, thereby possesses a humidity of 8-10%
5. Absolutely dry. Her drying conditions were previously indicated. Humidity is 0%

You can see the uneven distribution of water in different parts of the tree. Thus, the barrel contains less water than roots and branches; The bottom and top of the trunk is greater than the average; Crooked coniferous trees contain more water than ripe and sound wood. In coniferous rocks, in turn, the humidity of the nucleus is less than that of deciduous trees, and the moisture in the cross section is less uniformly distributed. Considering the bark is noted a significantly smaller humidity of the peel than the Luba, about 7-10 times.

Regarding the moisture content of the freshly served tree - it is 80-100%, this indicator is 2 times more at all. And on the example of coniferous rocks, the humidity of the nucleus is less than 2-3 times the humidity of the disease.

In the construction industry, the degrees of humidity distinguish several less than in general consideration:

1. Fresed. The humidity of such wood depending on the microclimate, the soil and time of the cut is from 50 to 100 percent.
2. Air dry. Wood dried naturally in air. The humidity of such wood is comparable to air humidity in the region where it dried and can be on average 15-20%.
3. Indoor dry. Wood dried in heated room, the absolute humidity of such a material is 10-14%; You can also note wet wood, it turns out during a long stay in water, the absolute humidity of such wood up to 200 and higher than percent.

Water types in wood are also distinguished, it can be hygroscopic and capillary. From these species and develops the level of humidity of the material. Gigroscopic moisture is in the walls of the cells, the capillary in turn directly in the cells themselves. Free, or capillary water from wood is removed at times less, also less affects the properties of the material.

The saturation of wood moisture at the initial level is carried out using hygroscopic water and only after a complete filling of the cell walls begins to fill directly the cells themselves. For this reason, it is the change in the associated (hygroscopic) moisture that causes a slowdown, stop or accelerating the processes of warping, drying, changes in the properties of strength and elasticity. At that moment, as a change in the level of free moisture, practically has an impact on any properties and processes.

Water absorption is the unique ability of wood to absorb water with long finding with it in direct contact. Since the tree is a natural material, it is very susceptible to changes in the microclimate. The main property that the ability to adapt to various climatic conditions is hygroscopicity, i.e. The ability of the material to change the level of humidity, adapting it, under the level of the environment.

Wood has the so-called "breathe" property, that is, it distinguishes or absorbs air pores when the microclimate changes the surrounding medium. These processes are used due to cell walls. It should also be noted that with a constant, unchanged microclimate, the material will gradually strive for a constant level of humidity, which is referred to as stable or equilibrium.

Gigroscopicity - the property of wood is adapted, i.e. Change the level of its humidity, corresponding to the change in humidity of its environment. In most wood breeds, the hygroscopicity indicator is 30% at a temperature mode of 20 degrees Celsius.

As already mentioned earlier moisture in wood to share for two types: connected and free. It is the amount of associated humidity indicates the level of hygroscopicity, and its maximum amount of the limit of hygroscopicity. This limit may vary depending on the temperature regime, at 20 o C, it is 30%, when the temperature changes, the connected moisture goes into free and vice versa.

Material moisture level drop by drying. A chemically bound moisture may be present in the wood, usually substances that are part of the material, they can be eliminated by chemical processing.

The limit of hygroscopicity does not differ depending on the wood breed. In most cases, it is 30% of the mass of wood (at a temperature of 20 degrees Celsius), this is a kind of saturation point. The rest of the saturation of wood with water occurs due to free moisture.

When a change in the level of humidity, depending on the nature of the change, the wood can be soaked, with a decrease in the level of moisture, or swell, when it is increased.

In most cases, the visible change in dimensions is observed in cross section, it is less common in the longitudinal one. Speaking of dense wood, fashionably mention its greater weight and, accordingly, greater level of swelling or drying.

In the cavity of wood cells, there is free moisture, in the walls of the cells associated accordingly. The standard timber saturation limit is 30%, and with a decrease in the level of moisture, the material dryness occurs accordingly.

If the saturation limit in all breeds is almost the same, then the ability to absorb moisture depends directly from the individual structure of the material, and, accordingly, from the rock. Some of the most hygroscopic rocks can be noted, Kempas and Pear. They react as quickly as possible to changes in the microclimate and immediately begin to change themselves.

There are also stable types of rocks that are practically not amenable to change (if there is no global change in temperature and humidity), such as oak, Merbau and so on. The bamboo wood can also be attributed to their row, which has a high level of stability to change climatic conditions and adverse environmental impact, this is one of the few species that can be even put on the floor of the bathroom.

The level of humidity in each of the rocks is also different. Low moisture wood up to 15% (maple, birch) has a tendency to rapid drying and further cracking. Moderate moisture material, up to 20% (walnut, oak), dries slower and has greater resistance to the formation of cracks. Taking into account the material of high humidity, up to 30% (for example, alder) we can say that it has a lot of resistance to drying, and according to the formation of cracks on the surface.

To determine the physico-mechanical properties of wood, it is tested by the wood, arguing to normalized humidity, on average this value reaches 12%, by air conditioning at a temperature of 18-22 degrees and air humidity of 60-70%.

Determination of wood moisture

To determine the level of humidity of the material, several methods can be distinguished.

1. In domestic conditions, this is done with the help of a special device - an electrolylagometer. The device determines the humidity based on the testimony of changes in the electrical conductivity of wood. Needles with diodes are conducted from the device, and are entered into a tree, after which the electric current is carried out, based on the conductivity data, the device shows the level of humidity in the place where the needle is introduced.
2. Also knowing the physical properties of the material, the type of wood, its density, etc., can determine this indicator by weight, warping and other signs.
3. Taking into account the color of the crust, you can define freshly stewed or ripe wood, as well as the level of its humidity.
4. If you do not need an accurate moisture rate, then you can determine the chips if it is crushed, it means that the material is wet, if it breaks or crumble, then the material is sufficiently dry
5. Wood with elevated moisture levels quite well, and on the spot where the cut remains wet traces.

Watering of sawn timber is determined by the following formula:

Where M C and M 0 is the mass of the original and dried material, respectively.

Those. In fact, this indicator is determined or by weighing or using a special instrument.

The moisture content of alloy wood - 200%, freshly served - 100%, air-dry - 15-20%.

Drying wood

Drying wood provides a process for removing moisture from the material to a certain value.

Brilliance of wood - the property of the material to reflect the sun rays falling on it. It depends on the wood of wood, the degree of its smoothness and the highlighting indicators. A high level of possession by this property differs the rocks most of the surface of which form heart-shaped rays. It is a decorative property and is taken into account when determining the tree of wood.

The dielectric property of wood is the ability that characterizes the dielectric permeability of the material.

The swelling coefficient is the value of the average swelling of the material with an increase in the moisture level by one percent.

Drying Coefficient - the value of the average drying with a decrease in the humidity level by one percent.

Balance - the property of wood is modified, that is, lose its dimensions and shape under the influence of the environment.

Boxing is longitudinally and transverse. The transverse depends on swelling and drybill relative to the radial and tangential direction, it is caused by several factors:

1. Location of annual layers
2. Place Vepiler
3. Form of cross section

The longitudinal depends on the presence of wood vices: slopes of fibers, swirls, etc.

Also, the violation of various types occurs when the equilibrium of stresses in the material during further processing (milling, division on the thinner boards, etc.)

Longitudinal jumper is most often occurring in mechanical change in the shape of the cross section of materials that are cut from different parts of the tree, or during drying.

The dried wood has a great level of strength, less undergoing the charge, not susceptible to rotting, is quite easily glued, as well as more durable than wet.

One of the large flaws of the sawn timber is a sensitive reaction to changes in the microclimate of their environment. In this connection, with increasing moisture, it absorbs water, and when in a dry room, the opposite gives moisture, as a result of which he dries and rolling.

In order to avoid the destruction of the material structure, it is necessary to maintain constant air humidity, for an open medium it is about 18%, for closed rooms 10%.

There are also many wood drying methods. The first is a natural drying, or atmospheric. At the same time, the wood is dryed out on the open space. It is necessary to put it in the shade, also to provide a shed and the presence of draft. To dry in the Sun, the tree cannot be sung, because in this case the upper part is quickly dried, while the inner remains raw, which has its own minuses. As a consequence, due to the difference in voltage, cracks appear to the surface, the process of warping is accelerated.

When drying a bar or boards, they should be folded with stacks on the foundation, or any base of at least half of the meter. The boards are stacked upwards, it reduces the chance of charging. When drying on the edges, of course, the process will go faster, but also the level of the charge will be several times higher.

Also to reduce the swinging when drying the wet, it is recommended to equip a heavy cargo over stack. Also, the ends of the bar should be painted with oil paint or other water-repellent material, it will avoid their cracking. The processing process must be started immediately after cutting.

In case the material has a high level of humidity, the ends are pre-dried by a soldering lamp, and only after that processed. The board itself is completely cleaned from the bark, for faster drying and prevent damage to insects. It should be noted that wood not purified from the cortex quickly begins to start and exposed to fungal affection. Usually after this type of drying, the moisture of the material is 12-18%.

There are other ways to dry.

1. Evaporation. This method was used in times of Russia. The essence of the process is as follows. The material was cut on the workpiece of the required size, after which it was placed in a cooled furnace for several hours, at a temperature of 65-75 degrees. Thus, this is the most evaporation. In the process, natural juice was displayed from the material and it acquired a light chocolate color, thereby emphasizing the natural pattern of wood. Such a material was subsequently treated, and after the drying was completed, it became less susceptible to cracking and warping.
2. The second way is paraffinating. It consists in treating the material of paraffin and its further drying in the furnace at a temperature of 40 degrees for several hours, and then within a few days at room temperature, and later the material did the same properties as when evaporation.
3. Best in linen oil. It provides for the filling of the capacity with flaxseed oil into which after the billet is lowered and the slow heat is written in it. After such a procedure, wood acquires a high level of waterproof and is not subjected to cracking.
4. Linear drying - provides for a decrease in linear dimensions of the material by removing the bound water from the cell walls, also discusses the options inverse, wood swelling by increasing the percentage of water.

Normalized humidity - material moisture level achieved under regulatory conditions (humidity 60-70%, temperature 18-22 degrees)

1. Volumetric drying - provides for a complete removal from the material of the bound water.

Volumetric swelling - provides for an increase in the level of bound water in the walls of cells to the limit.

Relative humidity is determined by the percentage of the mass of moisture to the mass of the material in the wet state. Since the wood is hygroscopic material, then it strives for equilibrium humidity relative to the surrounding microclimate. For example, at an air temperature of 20 degrees and humidity, 100%, equilibrium by these values, the moisture of wood will be 30%.

It should be noted that the rapid change in wood moisture will lead to a warping or vice versa to swelling.

The more massive element, the more attention should be given to it with drying, since uneven drying entails the formation of cracks. When operating wooden structures, sharp drops of temperature and climatic regime should be eliminated if it seems possible.

Regarding each of the directions, the value of the dermisk is different. Thus, in radial it is 4-6%, and in a tangential 6-12 percent. As a result of this unevenness, in the drying process, there is a small warping.

It should also be aware that with a sharp drop of microclimatic conditions in the material there is an internal voltage, which leads to strain and cracking the wood. The recommended room temperature in which the wooden elements of 20 degrees Celsius are equipped, with a humidity of 40-60%.

The regulatory level of moisture for wood, which is used for construction purposes, especially for the production of glued materials, 8-15%. Consequently, the material requires a mandatory drying. In turn, the natural drying takes longer, in this way the drying of the board with a thickness of 5 centimeters under regulatory conditions (temperature 18-22 degrees and humidity 50-60%) takes 30-40 days. Artificial drying will take several times less time - 5-6 days, and at elevated temperatures, drying time is reduced to 3-4 hours.

The humidity of the material after drying must necessarily comply with the operational standards for one or another type of work.

With long-term drying, moisture from the material evaporates, which can lead to significantly deformation. The drying process itself lasts until the material reaches a certain limit on moisture indicators, the limit depends on the microclimate in which drying passes. Similarly, the process of absorption of moisture is also. Also, in some cases, the destruction is carried out - that is, a change in the size by removing the bound moisture, with the removal of free moisture, the destruction does not occur.

Like drying, the dermisk affects the linear dimensions is not directly proportional, so the destruction in the tangential direction is up to 10%, and in the radial just up to 3.5%

With a continuous process of drying, moisture in the wood decreases to a hygroscopic limit, that is, up to 0%. When carrying out such a procedure, it is necessary to carefully monitor the uniform distribution of moisture, otherwise the internal stress may be formed, which causes the deformation, changes in the size of the mechanical processing of wood.

The process of convective drying itself determines the uneven distribution of moisture, which contributes to uneven dried material, and in the future and the occurrence of internal stress.

For regular readers, customers and visitors of my site, I post GOST-S regulating regulations (%) of humidity of planed dry products. Specially systematized and combined into one table, where and in which construction and carpentry works these products are used. See Tab.

The regulations of the humidity of planed dry products. Use in construction and joinery.

Planed dry product	Purpose	Using	GOST	Humidity,%
board, Barlok.	internal work	floor manufacturing, plinth, platband, windowsill	GOST 8242.	12 ± 3.
board, Barlok.	internal work	sling Roofing System, Obsek, Counter-Complete, Furniture		12 ± 3.
bar, Board, Bar	outdoor work	the rafting roofing system, the manufacture of a wooden structure frame and its skin.		15 ± 3.
board, Barlok.	other outdoor work	production of fences, lining of small wooden buildings		12 ± 3.
from solid wood	outdoor and internal work	bearing structures - floor balkans, floor lags, window (placada) windows and doors, friend. Bearing elements	GOST 4981.	up to 20.

Simply looks like this:

Check this regulation to the customer is simply necessary, because in my opinion:

Check on the eye stated by the supplier characteristics, respectively, to trust the supplier your money, the action in my opinion bordering with the real madness!

Which way I fulfill a complete check of the stated characteristics on the site before delivery to my customers, I suggest the reader to visit a whole section of my articles dedicated to each cross section separately. In which the details and conditions are disassembled in more detail: - how to check the customer of its supplier of planed dry products.

Care Characteristics of sections of planed dry lumber, held by me before delivery Customers of the site Torgless Moscow-

The photo shows the verification of the customer of the site of humidity of the finished planed dry product on the trading areas of Torgles Moscow before delivery. Check is made by a German needle moisture meter, because The needle moisture meter gives the minimum error in the measurements produced, i.e. Allows you to establish how much the GOST regulation is performed on chamber drying.

For what you need this GOST will look at the example.

For clarity, the public photo of the material that not when was not in the drying chamber. Those. The whole technological cycle of production was broken.

Namely, the natural humidity board was routine on the machine breaking an important technological cycle -chamber drying!

In the photo below, in front of the reader flooring with a cross section of 140x35x6000mm. Natural humidity. I notified with red circles defects because of which this material, after processing on the machine, cannot be used for direct purpose - flooring flooring in the house.

On separate fragments of this profiled plank, significant defects are visible:

Defects	Cause
Zadira and dimensioner material.	the blades of the machine cannot normally treat the surface of the material due to its high non-homogeneous humidity
- Easy of individual fragments of wood on the front of the board	the blades of the machine cannot normally treat the surface of the material due to its high non-homogeneous humidity;
- Very much noticeable "comb" from the work of an unevenly operating machine	the machine cannot normally treat the surface of the material because of its high non-homogeneous humidity
- Spool curve and "walks" size, then more, less. Hollows are simply not possible to further connect to Shim-groove	it is here that it seems that the board was not in the drying chamber, because The machine can not normally treat thin elements of the profiled board
- The resulting rapid process of warping in the wood	Indicates that the board was not in the chamber at all, because The board began to bend the letter "z"

In today's article, explain how important the natural moisture of wood in the manufacture of log cabins is.

Log cabins of natural humidity log

In recent years, wooden architecture is becoming increasingly popular and in demand. The desire of people to live in a house of natural environmentally friendly material is understandable and natural. In addition, the tree is a natural construction material of the Midground strip. The body is perfectly harmonized with natural material, and wood helps to get rid of the negative impact of the hectic life of urban residents.

It is intended to build, it is necessary to understand that the logs of natural humidity houses are durable and reliable, it is confirmed by centuries-old structures scattered throughout Russia, once fulfilled by our ancestors and easily undergoing changes in climatic conditions, war, snowfall, storms and floods. The masters of ancient architecture in one voice claim that the wooden house is to build solely from the natural moisture of wood.

In the old days, a chopped house was built only from logs with normal natural humidity. Specialists have long noticed that such a structure is better withstanding any cataclysms and sharp changes in weather conditions. The house will not give shrinkage, the moisture content of the natural drying wood allows the walls to breathe normally, not gaining extra moisture. A tree, like any living organism, is required for a normal existence of a lot of water. The logs going on the construction of the house should contain an optimal amount of moisture that allows the design to remain durable and monolithic.

Frams of natural humidity houses, advantages:

Existing types of sawn timber

1. Wet wood One hundred percent humidity happens after a long detention of a tree in water. Such material is strictly prohibited from any construction.
2. Fresed wood Natural humidity has in its structure from fifty to eighty percent of moisture. Parameters directly depend on the time of year and the velocity of cutting.
3. Wood Air-dry It has humidity no higher than twenty percent. This material is usually stored for a long time in the open air with natural changes in weather conditions.
4. Room and dry wood A long time is stored in covered warehouses and humidity does not exceed ten percent.
5. Fully dry wood It turns out when forced drying in special premises, the moisture content of the lumber does not exceed two percent.

How important is the moisture of wood of natural drying during construction

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Wood is a rather porous material containing a large amount of capillary filled with moisture. In practice, the moisture of wood is defined as the ratio of the weight of the water contained in the tree to the weight of absolutely dry wood. There is the concept of "free" and "bound" moisture. "Free" moisture is contained in the pores and capillary of the tree. "Related" moisture that is contained directly in wood cells.

When drying, the tree gives a destruction - decreases in the amount (volume). At the same time, the size decreases along the fibers (along the length of the board) is practically not occurring, but in the direction, the transverse move of the fibers, there is a significant change in the size (in the thickness and width of the board). The magnitude of this change depends on the wood breed and the specific value of changing the moisture content of wood. In the life, the most unpleasant surprises are associated with changing the width of the board.

For example, if you make a floor with a natural humidity board, then a decrease in its width over time can be so significant that two neighboring boards lose the engagement with each other. In this case, to remove the cracks, you will have to tear off all the boards from the lag and to be reinstalled, to intoxicate.

"What kind of humidity should there be a board?", - You ask. Everything is simple - any wooden product, in the process of its operation, seeks to the so-called "equilibrium moisture." "Equilibrium humidity" is determined by the temperature and humidity of the air in the environment where the board will be. The values \u200b\u200bof this humidity you can see in the table. For residential premises, it averages 8-10%, for the street it averages 12-14%. It is logical from this that the crude board will be inserted in the room, losing in its width, on the other hand, the dry board will be moisturized outdoors, expanding.

Natural humidity, finite wood moisture

Natural humidity - This is humidity inherent in wood in a growing or just cut (sawn) condition, without additional drying. Natural humidity is not normalized and can be from 30% to 80%. Natural wood moisture fluidity varies depending on the conditions of growth and season. So, the natural humidity of fresh trees in the "Winter" Forest traditionally less humidity of fresh trees in the "summer" forest.

Initial humidity - The same as natural humidity. Only a fired tree has a maximum humidity, which for different breeds may even exceed 100%. Balz tree may have moisture in a freshly powerful state that gives up to 600%. In practice, we are dealing with less values \u200b\u200b(30-70%), because After logging, some time passes until the cutting of the tree and placing it in the dryer and it, of course, loses some amount of water. We accept for the initial humidity, the value of the moisture of wood, which it has before shipping into the drying chamber.

Finite humidity - This is the humidity that we want to get after the complete drying cycle. In this case, the appointment of the product is made from dried wood is taken into account.

First of all, wood drying is the process of removing moisture from wood by evaporation.

Wood drying is one of the most important operations in the process of wood processing. Wood dried after sawmill, but in front of woodworking. The wood is dried in order to protect it with the lesion by wood-painting and wood-cutting mushrooms during its further storage and transportation. Drying warns wood from changing shape and sizes in the process of manufacturing and operating products from it, improves wood finishing, gluing. The humidity to which the wood is dried depends on the sphere of its further use. The whole point is reduced to bring the humidity of the board to the same meaning that would have achieved the product from this board during operation in these conditions. Such a moisture value is called "equilibrium humidity", it depends on the humidity and temperature of the ambient air. For example, a board from which the parquet and other outline will be made, operated indoors - should have a humidity of 6-8% as this humidity will be equilibrium. For products that will be operated in contact with the atmosphere, (for example: wooden windows, the outer covering of the house) of the equilibrium humidity will be 11-12%.

You ask: "What will happen otherwise?" We answer: otherwise, it will be what is found in Russia completely and nearby, namely the consumer will face problems. Imagine that you bought the wall paneling in order to sew walls inside your country house or giving. If you buy a lining with a raw board with a raw board and tighten the walls of your home, it will begin to slowly dry out naturally in the already established state. Turn to the table of equilibrium humidity and experience. If you natope in the winter room up to 25 degrees Celsius, then with a standard air humidity inside indoors in 35%, the value of equilibrium humidity for the board in such a room will be 6.6%. At bases and markets, the lining can very often have moisture from 14% and higher (we met and 30%). Next, imagine that your lining begins to dry, losing water from my pores. The hike is a process called "dry" and expressed in a decrease in the size of a wooden product. The value of the heatheus depends on the wood breed, the direction of fibers in the product, etc. The main sweep is across the fibers (respectively, the thickness and width of your clapboard). When your lining will dry in the prescribed state to an equilibrium moisture, you, at the most worst case, you risk not just to see that the skin has diverged, and get the slots between the boards, almost a finger.

In industry, various wood drying technologies are used, differing in both the equipment used and the peculiarities of heat transmission drying material.
The classification of species and drying methods is usually based on heat transfer methods for which four wood drying technologies can be distinguished:

• convective drying technology;
• conductive drying technology;
• radiation technology drying;
• electrical drying technology;

Each type of drying can also have several varieties depending on the type of drying agent and features of the equipment used for wood drying. There are also combined wood drying technologies, in which various types of heat transfer (for example, convective dielectric) are used at the same time, or other signs of various wood drying technologies are combined.

Independent drying technologies

Chamber drying

Chamber drying. This is the main industrial wood drying technology, carried out in the forest-drying chambers of various designs where lumber is loaded with stacks. The drying occurs in the gaseous medium (air, flue gases, overheated pair), which by convection transmits heat heat. For heating and circulating the drying agent, the drying chambers are supplied with heating and circulating devices.

In the chamber technology of drying wood, the timer drying deadlines are relatively small (from tens of hours to several days), wood enhances any given ultimate humidity with the required capacity, the drying process is amenable to reliable regulation.

Atmospheric drying

The second on the meaning and distribution in sawmills the method of industrial wood drying, carried out in the stacks placed on a special open territory (warehouses) washed by atmospheric air without heating. Advantage of atmospheric technology drying wood-relatively low cost. In addition, this method is the most gentle. Disadvantages: seasonality (winter drying is almost stopped); big duration; High end humidity. The atmospheric wood drying technology is used mainly for drying lumber in sawmills to transport humidity and on some woodworking enterprises for drying and aligning the initial moisture content of lumber before drying in drying chambers for wood.

Drying in liquids

Drying in liquids is carried out in baths filled with hydrophobic liquid (petrolatum, butter) heated to 105-120 ° C. Intensive transmission of heat from fluid to wood allows to reduce drying period compared to chamber 3-4 times, with other things being equal. This method is used in wood canning technology to reduce its humidity before impregnation. Attempts to apply the drying of sawn timber in petrolatum at woodworking enterprises did not give positive results due to the fact that lumber after such a drying do not meet the requirements for wood for furniture and joinery and construction products.

Conductive drying technology

Conductive (contact) wood drying technology is carried out by means of heat transfer with thermal conductivity when contact with heated surfaces. It is used in small volumes for drying, thin wood materials - veneer, plywood.

Radiation drying

The radiation drying of the tree occurs when heat is transmitted with radiation from heated bodies. The efficiency of radiation drying is determined by the density of the flow of infrared rays and their permeability in solid wet bodies. The intensity of the flow of radiant energy is weakened as depicted into the material. Wood belongs to infrared materials lowered for infrared radiation (the depth of penetration is 3-7 mm), so this method does not apply for drying of sawn timber. It can be used for drying thin-sheet materials (veneer, plywood), in addition, this method is widely used in wood finishing technologies for drying paintworks. Electric stoves, electric heating elements, gas (flameless) burners, incandescent lighting electrollamps from 500 W and higher are used as emitters.

Rotary drying

Rotary drying of wood is based on the use of the centrifugal effect, due to which the free moisture is removed from the wood when it rotates on centrifuges. Mechanical removal of free moisture is achieved with a value of centripetal, acceleration of at least 100-500g (G - acceleration of free fall). Such accelerations due to the difficulty of accurate balancing centrifuges with a stack in practice have not yet been achieved, only experienced developing appropriate devices are underway. In well-known industrial rotary dryers, the centripetal acceleration does not exceed 12G. Under these conditions, mechanical dehydration is manifested to a small extent. However, the intensification of the drying process in the humidity range above the hygroscopicity limit is observed.

When installing the carousel in the drying chamber, the drying technology of sawn timber is the same as in conventional periodic chambers. Duration of drying at the first stage (from initial humidity to the limit of hygroscopicity) is reduced several times depending on the thickness, rock and initial moisture content of wood compared with the usual convective dryer with the same modes. Although rotary dryers are economical and provide high quality drying, industrial use for drying lumber rotary method has not yet found.

Vacuum drying

Vacuum drying under reduced pressure in special hermetic drying chambers. Due to the complexity of the equipment and the impossibility of obtaining a low ultimate moisture of wood, a vacuum drying of an independent value has no value. It is used in combination with other drying methods and as an auxiliary operation in the preparation of wood to impregnation.

Dielectric drying

Dielectric drying is a drying of wood in an electromagnetic field of high frequency currents, in which wood heating occurs due to dielectric losses. Due to the uniform heating of wood throughout it, the occurrence of a positive gradient of temperatures and overpressure inside its duration of the dielectric drying is ten times less convective. Due to the complexity of equipment, a large electricity consumption and not enough high quality drying, the dielectric drying actually does not find a wide application.

Combined wood drying technologies

The use of combined wood drying technologies is more efficient, such as convective dielectric and vacuum-dielectric. For mass drying, the use of these methods is not economically, but in some cases, especially when drying, expensive, responsible lumber and billets made of hardwood breeds, these methods can be used.

Convective dielectric drying

With a combined convection-dielectric technology, wood drying to a stack loaded into the chamber, equipped with thermal and fan devices, also apply high-frequency energy from a special TVH generator through electrodes located near the stack.
The consumption of heat on the drying in the drying chamber is mainly compensated by the thermal energy of the steam supplied to the calorifers, and high-frequency energy is supplied to create a positive temperature difference over the material cross section. This drop, depending on the characteristic of the material and the rigidity of the specified mode is 2-5 ° C. The quality of the convective-dielectric drying of lumber is high, as the drying is conducted with a small difference in the thickness of the material.

Vacuum-dielectric drying

This is another way of drying wood using TWH energy with this technology use advantages and vacuum and dielectric drying. Due to the heating of wood in the TWH field under reduced pressure, boiling water in the wood is achieved at low temperatures of wood, which helps to preserve its quality. Move moisture in wood with vacuum - dielectric wood drying is provided by all major driving forces of moisture transfer: a gradient of moisture content, temperature, overpressure, which reduces the duration of the drying.

With a vacuum - dielectric dryer, the lumber stack is placed in an autoclave or hermetic chamber, where the vacuum pump is created by a reduced medium pressure (1-20 kPa). The lower the pressure of the medium, the lower and the evaporation temperature of moisture and wood during drying. Consumption of heat drying is provided by the high-frequency energy to the wood. When using this technology, drying wood also occur operational difficulties - the complexity of the equipment, especially the commissioning and operation of high-frequency generators, the high flow of electricity to drying. Therefore, in solving questions about the use of vacuum - dielectric cameras, it is necessary to develop a feasibility study at the terms of a particular enterprise.

Induction, or electromagnetic wood dryer

The method is based on the transfer of heat material from ferromagnetic elements (steel grids) laid in a stack between rows of boards. Stacking together with these elements is located in an alternating electromagnetic field of industrial frequency (50 Hz) formed by a solenoid mounted inside the drying chamber. Steel elements (grids) are heated in the electromagnetic field, transmitting heat and air heat and air. In this case, a combined heat transfer material is happening: conductive from the contact of heated meshes with wood and convection from circulating air heated as well as grids.

Wood moisture is a value that shows the level of moisture exchange between wood and air. Since the humidity of the environment is changeable, then the wood is constantly changing. The level of this indicator affects the quality and application of sawn timber. Products with high humidity are more susceptible to mold and fungus, rotting and deformation. Therefore, dry raw materials are chosen for the construction and manufacture of wooden products.

Humidity is absolute and relative. The first represents the ratio of the mass of moisture of wood to the mass of absolutely dry wood. A more consumable, comfortable and simple value in the calculations is considered relative humidity. This is the ratio of the mass of moisture of wood to the total mass of the tree, which actually reflects the water content in the product. This value is determined, so it is applied in practice.

Humidity Wood Types

The initial indicator, as a rule, is 50-60%. With a natural dryer after 1.5-2 years, it drops to 20-30%, after which it does not change much and remains at about 25%. Allocate crude wood with humidity above 35%, semi-dry with an indicator of 25-35% and dry - less than 25%. To reduce moisture level to room and dry 7-18%, lumber dried in special drying chambers.

The following types are distinguished:

• The alloy tree, which was in water for a long time or well sent and wetted log - over 60%;
• The initial indicator of the freshly dredged tree is 45-60%;
• Air dry reaches 20-30%. This result is characteristic of logs and timber, which the long period was outdoors or were located in a dry well-ventilated room;
• Indoor-dry is dried in rooms with heating and good ventilation or in special chambers. Is 7-18%;
• Absolutely dry wood with a humidity of 0% is dried to a constant mass at a temperature of 100-105 degrees above zero.

For the construction of a house or baths use dry lumber with humidity up to 20%. Today, the safest and most effective method that allows you to achieve such indicators is a condensation drying. When drying, hot and cold air is used. This prevents the emergence of marriage and defects on a log or bar, reduces the amount of cracks and allows you to get high-quality, durable and dry lumber. Read more about condensation drying.

Log and bar for building a house

In "Marisrub" you can order the construction of wooden houses only from high-quality and carefully selected dried materials. We independently make a log and a timber under the project of a wooden house, bath, gazebo or garage. Choose individual design or refinement of the ready-made option that you will see in.

In the manufacture of applying a condensation drying, we comply with the requirements of GOST, storage and transportation norms. We carry out antiseptic and control each stage of production, which allows to obtain durable and high-quality lumber. Due to this treatment, the tree retains the initial color and natural properties for a long time. It does not rot and does not darken, it is not covered with mold. Materials are resistant to moisture and cold, wind and insects, to temperature drops.

Build wooden houses from a bar and logs from the manufacturer. Own production - Warranty of quality and low lumber prices! We offer a turnkey construction, which includes the creation of a project and the installation of a brusade or log cabin, the construction of the foundation and roof, finish inside and outside the house, installation and introduction to the operation of engineering networks. We guarantee high-quality construction on time!