How to measure moisture moisture moisture meter. Wood moisture meter (moisture meter): Types of device, Review of models. There are several types of wood moisture

For the use of wood for outdoor or external work, it is necessary to determine its humidity. There are several ways to "how to determine the moisture content of the wood." You can define an eye, and you can with the help of special devices. If you neglect this characteristic, then you can subsequently encounter an unpleasant situation, such as deformation or transformation into a crumb.

Without laboratory experiments, it is not difficult to notice the degree of moisture of material. If the moisture begins when the moisture begins, then this indicates a high degree of humidity, since its surplus is performed on the surface. Such a tree is unsuitable for use. If the tree, on the contrary, begins to crumble when he is cut, then this is a sign of dry material, which is also unnecessary for subsequent processing.

Setting the moisture content of wood can also be made by weighing. This method requires a sample for experience. First, the sample is put on the exact scales and write the measurement results. Then, for drying, the sample is placed in the brass oven, heated to one hundred degrees, for an hour. After that, we repeat weighing. This operation continues to stop changing the material, which means its complete drying. After the end of the experiment, humidity is calculated. For this, the end weight is subtracted from the initial weight. The result obtained is divided by weight of dry material. The result obtained must be multiplied by one hundred percent and the percentage of moisture is contained in the board.

There are also electrical appliances showing the level of moisture, called electrolylavera. They are based on changing the electrical conductivity of the material. The needles of the device are injected into the wood and direct current there. After that, the device displays the value of the degree of humidity.

Practically any wood give drying. Dried wood is more durable and durable, not exposed to rotting processes and less deformed.

There are I. folk Methods Definition of drying wood. Having conducted a line on the planing side by a chemical pencil. If the line does not get purpleThe wood is dry. Dry wood has a fragile chips, and raw - elastic. Sound from a knock on wooden material Also indicate the degree of humidity. Raw - the sound is deaf, and dry is soft and melodic. During drying wooden boardsThe resin protrudes at their ends. If, when pressing this resin, it begins to crumble, then this is a sign of wood dryness.

Summing up, you can draw the following conclusion: the quality of wood largely depends on the degree of its humidity. The land of the material, the more stronger and more resistant to rotting. Therefore, when choosing wood, it is necessary to take into account this fact.

Wood is natural materialwhich is very susceptible to changes in the level of humidity and temperature mode. The main property of wood is its hygroscopicity, that is, the ability to change the level of humidity according to the surrounding conditions. Such a process is called the "breathing" of the tree, while it can absorb air pairs (sorption) or highlights them (desorption). Such actions are a reaction to changes in the microclimate of the building. If the state of the surrounding does not change, the moisture content of wood will strive for a constant value, which is called the equilibrium (or sustainable) humidity.

June 02.

Direct - according to the technique, indirect - with the help of electrical. The first method is accurate, the second method is fast.

Determination of Wood moisture according to GOST 17231-78 (GOST 16483.7-71)

Method of the first - straight (standard, grandfathers, tested by time)

On the this moment, in Russia there are two standards, both regulatory the same method of determining wood moisture:

GOST 17231-78 Round timber and round.
Methods for determining moisture
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GOST 16483.7-71 Wood.
Methods for determining moisture
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Analogs of these standards are easy to be delayed in the metrology of any post-Soviet country. Both documents (GOST 17231-78 and GOST 16483.7-71) regulate the procedure for sampling, test methods and analysis for objective determination of the humidity of the vehicles, timber and firewood (all of the time where you can cut or unscrew the sample for research). The method of determining humidity according to GOST 17231-78 and GOST 16483.7-71 is extremely simple and consists in a systematic selection and subsequent drying of samples of the test material. At the same time, the studied sample is in drying cabinet To full drying. After that, weighing and comparing the weight of the wood studied before, and after drying.

Approx. According to GOST 17231-78 and GOST 16483.7-71, such a sample is considered to be such a sample, the mass of which has not changed by more than 1% after keeping in the drying cabinet for 24 hours at a temperature of 101 ... 103 ° C

Pros and cons

GOST-OSH METHODS OF WORK WORLD METHODS Very objective, but have one large disadvantage - They are cumbersome and slow. Analysis of wood on humidity can stretch to 3 days until samples dry. In addition, it requires a sample from the mass of the material under study, which is absolutely unacceptable to determine the moisture content of wood finished products

Determination of Wood moisture moisture meter

The second method is indirect (fast and modern)

In order not to bother with tedious selection and dried samples, it is much easier and more convenient to "poke" in the wood moisture meter. Moisture meter - This is a special electrical device for determining wood moisture. The action of the moisture meter is based on the principle of changing the specific electrical resistance of the wood, depending on its humidity. The moisture maker has special electrodes needles that need to be in contact with the studied wood and simply press the button. The measurement result will immediately highlight on the screen (or will be indicated by the deviation of the arrow to the desired value if the device has a lever-type scale).

Pros and cons

The determination of moisture of wood moisture meter is incredibly quick and convenient, refers to non-destructive method Control and, therefore, ideal for finished products. Alas, electric moisture makersgive a big error

Measurement errors when determining wood moisture

Error in measuring wood moisture make up

According to the technique, not more than 1%
When using electric, in the range of 2 ... 10%

Why such a big error when using moisture meters:

The needles electrodes penetrate locally, only to a depth of 5 ... 15mm. Because of this, it turns out a superficial and local study. wood material. As a result - a large percentage of error, compared with standard guest-octic methods, where the sample drying occurs throughout the volume

Using the principle of changing the specific electrical resistance of wood depending on its humidity gives an additional error. Because, the value of the specific electrical resistance of the wood depends not only on its humidity, but also from its density and resinness (for coniferous rocks). And since the wood is a very changeable value, then the likelihood of error is increasing when measuring the wood of trees in various density.
Therefore, for wood of each tree of wood there is own moisture scale. Electrical moisture makers are configured to the density of the wood of some kind of rock, as a rule - pine. For other wood breeds, manufacturers of moisture makers apply tables or embed calculators to cross the humidity.
But, even such tricks do not allow to reduce the measurement error less than 2 ... 3%, since the specific electrical resistance of the wood directly depends on the density of wood, which can be strongly changed even within the same breed of wood
cm.

Specific Wood Electrical Resistance Table Depending on the tree of the tree (visual allowance for explaining, why do we need tables to cross the moisture, depending on the tree breed when using electric moisture resources)

Breed of wood	Specific electrical resistance (humidity 0%, 20 ° C, Ohm * cm)
	alternate fibers	along the fibers
Pine	2,3*10 15	1,8*10 15
Spruce	7,6*10 16	3,8*10 16
Ash	3,3*10 16	3,8*10 15
Hornbeam	8,0*10 15	1,3*10 15
Cedar	2,5*10 16	1,9*10 15
Larch	8,6*10 15	3,3*10 15
Approx. These tables are found on the network, their authenticity is unknown. However, even a superficial view is enough to understand how much the value of the specific electrical resistance of the wood can be varied, which is based on the principle of operation of the electric moisture maker.

Measurement error Depending on the tree breed when determining the moisture content of wood moisture meter It decreases with the growth of this very humidity and practically disappears at a 100% indicator. This is explained by the fact that in the waters of wood electricity It is "directly" through water, "ignoring" with the resistance

Wood moisture measurement units

In some way, the moisture of wood was not measured - it is always expressed as a percentage of the total mass. Wood humidity is a quantitative indicator of the percentage of moisture in it. It goes without saying that the moisture of wood does not depend on the tree breed.

Free and bound moisture in wood

The bulk of moisture (water) is contained in the wood in intracellular and varnishing cavities and voids, channels, cracks, etc. But, besides this, the water molecules are contained in the chemically associated state directly in the thicker.

Depending on the location of moisture in the woody mass, it (moisture) is divided into two types - and

Free moisture

Free moisture is moisture, which is in intracellular and interclaim space, as well as in the cavities and voids of wood. Free moisture is also called "capillary". Free moisture is held in woody thicker due to simple mechanical connections and is easily removed from it when ordinary drying. Free moisture is water that wood can absorb in itself and then give to dry.

Related moisture

Related moisture is a specific term. The bound moisture is moisture, which is located inside the material of the walls of wood cells, directly in the very

Tree is natural material, very susceptible to temperature and humidity fluctuations. The main property of wood is hygroscopicity, that is, the ability to change moisture in accordance with the surrounding conditions. It is said that wood "breathes", that is, absorbs air pairs (sorption) or highlights them (desorption), reacting to changes in the microclimate of the room.

Wood moisture measurement with water meter

The absorption or selection of vapors is carried out due to cell walls. With constant condition ambient The level of moisture of wood will strive for a constant value, which is called the equilibrium (or sustainable) humidity.

On the ability to absorb moisture affects not only the microclimate of the room, but also the tree of wood. The most hygroscopic rocks include beech, pear, Kempas. They most quickly react to changes in the humidity level. Unlike them there are stable breeds, for example, Oak, Merbau, etc. These include bamboo stem, very resistant to adverse climatic conditions. It can be flattened even in the bathroom.
Different tree breeds possess different levels humidity. For example, birch, ram, maple, ash have low humidity (up to 15%) and when drying, have a tendency to form cracks. Oak and nut moisture and mild (up to 20%). They are relatively resistant to the formation of cracks and dry out not so quickly. Olha is one of the most resistant to drying rocks. Her humidity is 30%.

Humidity - One of the main characteristics of the wood. Under the moisture content of wood understands expressed in percentage of the mass of water to the dry mass of wood.

Absolute moisture of wood The ratio of the mass of moisture is called in this volume of wood, to the mass of absolutely dry wood. According to GOST, the absolute moisture content of the parquet should be 9% (+/- 3%).

Relative moisture of wood - This is the ratio of the mass of moisture contained in the wood, to the mass of wood in a wet state.

There are two forms of water in the wood - associated and free. Of them there is a total amount of moisture in the wood.

The bound (or hygroscopic) moisture is contained in the cell walls of wood, and the free occupies the age of cells and intercellular spaces.

Free water is easily removed than the associated, and to a lesser extent affects the properties of wood.
According to the degrees of moisture, wood is distinguished by the following types:

Wet wood
Her humidity is more than 100%. This is possible only on the condition that the wood for a long time was in water.

Freshlyructured
Its humidity ranges from 50 to 100%.

Air dry
Such wood is usually stored for a long time in the air. Its moisture can be 15-20%, depending on the climatic conditions and the season.

Room and dry wood
Its humidity is usually 8-10%.

Absolutely dry
Her humidity is 0%.

With prolonged drying, water from wood evaporates, which can entail significant deformations of the material. The process of moisture loss continues until the level of moisture in the wood does not reach a certain limit, which directly depends on the temperature and humidity of the surrounding air. A similar process occurs during sorption, that is, the absorption of moisture. A decrease in linear volumes of wood when the associated moisture is removed from it is called dry. Removal of free moisture debris does not cause.

Speeding Nonodynakova in different directions. On average, the complete linear dermisk in the tangential direction is 6-10%, and in radial - 3.5%. In a complete sweater (that is, such at which all the bound moisture is removed) the moisture of wood is reduced to the limit of hygroscopicity, that is, up to 0%. With an uneven distribution of moisture when drying wood can form internal stresses, that is, voltages arising without participation external power. Internal stresses may cause changes in the size and shape of parts in the mechanical processing of wood.

Wood properties directly determine the properties of wooden products. With excessive or insufficient moisture, wood usually absorbs or giving moisture, accordingly increasing or decreasing in volume. For high humidity In the premises, wood can swell, and with a lack of moisture, it usually dries, so everything wooden crafts, including floor coverings, require careful care.

To prevent the deformation of the floor covering in the room, it is necessary to maintain a constant temperature and humidity. This favorably affects not only on quality and durability. outdoor coatings and wooden furniture, but also on the health of people. With a sharp change in the temperature-humid regime in the room in the wood there are internal stresses, which lead in cracks and deformations.

The optimum indoor temperature with parquet floors should be approximately 200C, and optimum humidity Air - 40-60%. Hydrometers are used to monitor the temperature in the room, and the relative humidity in the room is maintained using air humidifiers.

Determination of wood moisture

There are several ways to determine the moisture content of wood. In domestic conditions, use a special electrolygizer instrument. The effect of the device is based on the change in the electrical conductivity of the wood, depending on its humidity. The electrical magometric needles with the supplied electric drives are injected into the wood and pass through them the electric current, while on the scale of the device immediately marks the moisture of wood in the place where needles are introduced.

Many experienced cutters determine the moisture content of the tree. Knowing the types of wood, its density and other physical sv-va, it is possible to determine the moisture content of wood by weight, by the presence of cracks on the end or along the fibers of the wood, for warning and other features.

In the color of the cortex, its size and color of wood, you can recognize ripe or freshly edged wood and the degree of its moisture. When processing the p / m of the plane, its thin chips, compressed by hand, is easily frozen - it means the material is wet. If the chips break and crumble, it indicates that the material is sufficiently dry.

With transverse cuts, sharp chisels also pay attention to chips. If they crumble or chosen the wood harvest itself, it means that the material is too dry. Very wet wood is easy to cut, and in the place of cutting from the chisel is noticeable marks. But in the end, high-quality threads are hardly able to succeed, since cracking, warping, and other addictions can not be avoided.

Drying wood

Drying wood - the process of removing moisture from wood to a certain percentage of humidity.
Dry wood has high strength, it is less breeding, not exposed to shockting, it is easily glued, it is better off, more durable. Any wood itself different breeds Very sensibly reacts to changing environmental humidity. This property is one of the shortcomings of timber.

With high humidity, wood easily absorbs water and swells, and in heated premises it dries and brends. The room is sufficient to the moisture of wood to 10%, and in the open sky - no more than 18%. There are many ways of drying wood. The easiest and most affordable - natural view Drying - atmospheric, air. It is necessary to dry wood in the shade, under a canopy and in draft.

When drying in the sun outer surface Woods are quickly heated, and the inner remains raw. Due to the voltage difference, cracks are formed, the tree is quickly brewed. Boards, timber and other p / m fit into the stacks on metal, wooden or other stands with a height of at least 50 cm. The boards are stacked by internal layers up to reduce their stacks.

It is believed that the drying of the boards put on the edges occurs faster, as they are better ventilated and the moisture evaporates more intensively, but they are more and more, especially the material of high humidity. The pile of p / m, prepared from freshly edged and alive trees, is recommended from above to seal heavy load to reduce the charge.

With natural drying on the ends, cracks are always formed, to prevent their cracking and preservation of P / m, the ends of the boards are thoroughly painted oil paint Or soak hot oil or bitumen to protect the pores of wood. Processing ends need to be immediately after transverse fuse.

If the tree is different high humidity, then the end dried by a flame soldering lamp, and then paint. The trunks (ridges) are deficatory (purified from the crust), only the ends are left for small rigs-clutch 20-25 cm width to prevent cracking. Corre is cleaned so that the tree be sinking faster and is not amazed with beetles.

The trunk left in the cortex, in relative warmth with high humidity quickly, is amazed by fungal diseases. After atmospheric drying with warm weather, the moisture of wood is 12-18%.

Wood drying methods

Warming methodOr wrying used in Russia for a long time. The billets are cut into parts, taking into account the size of the future product, lay in the ordinary cast iron, the sawdusts of the same workpiece are poured, poured with water and put for several hours into the drowning and cooling Russian furnace "tomit" at T \u003d 60-700C. At the same time, leaching occurs - evaporation of wood; Natural juices come out of the workpiece, the tree is painted, acquiring warm dense chocolate color, with a pronounced natural pattern of texture. Such a workpiece is easier to be processed, and after graduation, drying is less cracking and brewed.

Parafining methodThe billets are lowered into the melted paraffin and put in the oven at T \u003d 400C for several hours. Then the wood enhances the same for a few more days and acquires the same properties as after the rebel: it does not crack, does not breed, the surface becomes tinted with a distinct pattern of the texture.

Welding method in linseed oilThe dishes made of wood, stealing in flaxseed, is very waterproof and is not lightering even in everyday use. This method is acceptable today. The billet is put in the container, poured linen Oil And steamed on slow fire.

Tree - natural material, strongly susceptible to humidity. It is able to allocate and absorb moisture depending on the surrounding conditions. With the constant state of the microclimate, the moisture of wood is committed to constant indicators.

The determination of wood moisture depends largely on the tree of wood. The most hygroscopic are pear, beech, Kempas. The most persistent are the oak, bamboo, Merbau.

The use of wood for construction and repair involves compliance with the norms of humidity. Under the term "humidity" implies the percentage of water to dry wood.

Types of moisture

Severe two types of wet raw materials: relative and absolute.

Absolute

Such a concept is characterized by an attitude massword Moisture of a certain volume of wood to the weight of absolutely dry raw materials of the same size. This indicator exists established state standards. According to them, the indicators of the absolute humidity of the board must be in the boundaries of 9%.

Relative

This is the percentage of moisture, which is contained in the tree, to the mass of wet wood. In wood raw materials, water is in two forms: free and related. They indicate the total moisture in the raw material. The volume of associated moisture depends on the microclimate, as absorbed from the air. It is in the cellular structure of the tree. It is because of this, depending on the humidity of the environment, there is a swelling or destruction of the material. Remove the linked water can be possible only with drying.

Free moisture does not result in swelling, as water in this case is in the intercellular structure of the wood. But thanks to it, the density of the material increases.

In addition, the type of wood raw materials depends on the degree of its humidity.

There are several types of wood moisture:

Wet. To this category include a tree that has been exposed to water for a long time. In this case, the humidity meter indicator is more than 100%.

Fresed. The humidity of the recently feebled tree is within 50-100%.

Indoor dry. This type of material, which has long been in a heated building for a long time. Therefore, its number is within 9-13%.

Air dry. To such a type of wood belongs, which for a long time was kept by fresh air. Depending on the environmental conditions, its indicator is in the range of 15-20%.

Absolutely dry. Such indicators can only be achieved with drying in a special device. The amount of water in this case is 0.

How to find out the moisture of wood?

There are several methods how to identify wood moisture. But first we need to find out the type of plant and air moisture, because for different trees There are standards.

In order to measure the moisture of wood raw materials, as a rule, use two methods: weight or with help electric device. Their indicators may differ somewhat, but slightly.

Weight

For this method will need:

very accurate scales;

Measurement process:

To begin with, from the middle of the board, you need to saw a piece of 10-15 millimeters width. It will serve as a control breakdown. The main thing is, in this stage - to take a bar from the center of the board. It is not worth cut off from the end part, as it has a much smaller humidity.

After weighing, this piece must be sent to a special drying, the device with a temperature of about 100 °.

The first weighing is made with your own hands in five hours. All subsequent indicators are recorded with an interval of 1-2 hours.

Drying is carried out until the weight indicator starts to repeat. This means that the material has become absolutely dry. Denote by the numerical indicator of the last sample as "PC".

W \u003d (pH-PC): (PC x 100%)

W is an indicator in percent; PH - the first weight; PC - the last weight.

To get more reliable results, it is better to use two sample samples.

Electric

To conduct weight measurement of wood requires a lot of time. On average, about nine o'clock goes to such work. But there is a way that makes it much faster and more accurately determine the percentage of water in the tree.

Installing the humidity of wood raw materials is much easier with the help of an electric moisture maker.

The principle of operation of the moisture meter is based on changing the specific electrical resistance of the material depending on its humidity. The electrodes of this device are introduced into the wood so that they are against each other. There is a current on them, and the moisture meter shows the amount of water in this area of \u200b\u200bthe tree. But since the moisture meter measures moisture only locally, it is better to repeat the measurement in several places.

How to determine the moisture of wood without technical means?

Today, the amount of water in the wood raw materials is found with the help of complex calculations and the newest devices. But the construction of people always engaged in construction. And somehow they did without progressive methods and moisture meters.

On the freshly fresh fragment it is necessary to draw a pencil feature. When the wood is wet, the line will appear after a while, if dry - no.

On the number of water in wood raw materials can "tell" chips. If they are elastic, soft, do not break down - the tree is wet. Chips of dry raw materials in the hand will break, crumble.

You can spend with your own hands on wood metal subject. Under the left, the state of the material is determined. A wet tree trail will be wet.

It is possible to determine the amount of moisture in the wood raw materials, you can hit it by some wooden subject. If the sound is deaf - the tree is wet, thin and ringing - dry.

On wood dryness also testifies the cracks at its ends. The wet material is less.

When when sawing the board with their own hands, the moisture appears in the hole, the tree contains a large number of Water and unsuitable for work. Too dry raw materials in such a processing crumbs.

Wood humidity plays a huge role in construction and repair. Raw tree In the drying process will be deformed. To avoid working this, only with dry material.

The use of sawn timber and products from wood having excessive humidity leads to deformation wooden structures, loss of strength, development of fungus and mold. Humidity is the main controlled parameter at the stage of production of materials from a tree. After the forest processing, the resulting timber is subjected to drying, on wood processing enterprises, the control of moisture content is carried out by a laboratory. When achieving a given condition, wood enters consumers and to the trading network. Humidity rates for commercial wood are defined by GOST.

Laboratory methods use laboratory methods to determine the moisture content of the woodwood. Laboratory installations are equipped with wood processing enterprises and allow measurements with high accuracy. The method is based on determining the amount of moisture, evaporated from wood samples. The test process takes a long time, requires application special equipment: thermostats, high-precision weights.

The wood is hygroscopic, when storing and transporting the material absorbs moisture from the atmosphere. Before using timber, it is important to control its humidity. Wood express tests use moisture meters.

Wood moisture meter - electronic device allowing express analysis building material and wood products.

Instruments for measuring moisture of wood are distinguished by measurement methods:

Conductometric - based on measuring electrical conductivity between two points - electrodes,
DIELKOMETRIC - based on measuring the dielectric constant of the material,
To determine the reflection coefficient of IR radiation,
Under the weakening of microwave radiation, when passing through the test sample.

"MEGEON 20502"

The most common are needle (conductive) and non-contact (dielometric) moisture makers. Instruments working with microwave and infrared radiation are manufactured in stationary design and are intended for use on the tree processing flow lines and in the production of chipboard (chipboard).

Needle moisture meter

A conductive measurement method is used - the device measures the current strength flowing between electrodes embedded in wood. The instrument scheme is simple, includes: power supply, pointed electrodes, current value in the chain is measured by a microammeter. The needles electrodes are of size from 15 to 25 mm, made of solid metal, closed with a protective cover in a non-working position. The distance between the electrodes determine the developers of the devices.

The device determines the moisture content in percentage, the result is reflected on the display and does not require recalculation. The duration of one change does not exceed 5 seconds. A feature of contact models is a limited range of application: the maximum accuracy is achieved with a humidity of from 7 to 30%, large values The error increases significantly. The accuracy of measurements using needle moisture meters is affected by the tree of wood. It is recommended to use for measurements on wood that has not been chemical processing.

"DT-125H" "

The rules for determining the humidity of the piltroduction with the use of conductometric moisture meters are established by GOST 16588-91 and coordinated with the system international standards ISO. Measures are held in different places Billets: first - at a distance of 0.5 m from the end, follow-up - through each running meter. The needles are introduced vertically for the entire length, the line connecting the needles must be parallel or perpendicular to wood fibers. The device is widely used when working with a sawn timber: a board, a bar, a block house, which does not lose freight after piercing.

"MEGEON 20502", Russia,
"ADA ZHT 125", Hong Kong,
"Sem DT-125H", China.

"CONDTROL HYDRO-TEC"

The principle of contactless devices is based on measuring the average value of the dielectric constant (insulation coefficient) microwave. Water has high conductive properties. When placing the studied sample in the induced electromagnetic field, a high-frequency current is formed. The value of the current is proportional to the humidity of the medium. In contactless moisture meters, generators are used 3-30 MHz. A condenser is included in the high-frequency chain, the capacitor discharge rate depends on the dielectric permeability of the medium. The device produces quite complicated calculations, has a built-in microprocessor. By the complexity of the device, the contactless moisture meter is superior to needle moisture meters.

"MEGEON 20610"

Microwave is universal, can be used to determine moisture in various materials. It can be a tree, plywood, plasterboard, concrete, brick, plaster or cement strainer. Measurement results depend on the wood breed and the properties of the measured material. Modern contactless moisture makers have an option on the option of choosing wood and type of material.

To measure the measurement, the instrument sensor is pressed against the surface with an effort 1.0-1.5 kg, the measurement is performed within 10-15 seconds. The range of humidity measurement range from 4 to 85%, the depth of scanning is 20-30 mm.

In the top 3 popular models include:

"CONDTROL HYDRO-TEC", Russia,
"MEGEON 20610", Russia,
"Testo 635-2", Germany.

Psychrometer and moisture meter for wood do it yourself

When equipped with a joinery workshop, it is necessary to know the humidity of the room indoors and be able to control the quality of raw materials. You can make devices to control these parameters with your own hands.

The simplest psychrometer is a device for determining air humidity, can be made within 30 minutes. For this, two ordinary indoor alcohol thermometers are needed. Thermometers can be placed on the wall or on a special stand. The underlying condition - one thermowance the expansion flask with alcohol should be wrapped with a damp cloth. The thermometers will be different: the land surrounding the air, the smaller the temperature will show the "wet" thermometer. With increasing air humidity, the difference in the testimony will be less. More accurate humidity in the workshop can be determined using a special table available on the Internet.

The Internet offers many schemes for the manufacture of moisture meters with their own hands. If you calculate the cost of components, the cost of homemade will be comparable to the cost of the most simple industrial designs. Experienced masters cost without moisture meters, determine the moisture content of wood indirect signs: in the color and elasticity of chips, by sound - when the joinery of a carpentine, dry wood makes a characteristic ringing sound, and other features.

Basic selection parameters

Wood moisture makers are available to a mass consumer, various models Have their advantages and disadvantages. To work with lumber, you can limit the needle moisture meter, in the manufacture of furniture, work with plywood, MDF and Chipboard better Select a contactless model. Modern models Compact, have an LCD display, an intuitive interface and are equipped with additional options: temperature measurement, memorization of results, automatic shutdown, etc.

Features different types moisture meters are:

Needle moisture meters are the cheapest, characterized by simplicity and compactness, allow you to quickly perform measurements. This type of meters has a significant error in a sample humidity exceeding 30%. When measuring, the integrity of the surface is disturbed. The devices are designed to work with chemically raw lumber.
Contactless moisture makers are more expensive, equipped with an electromagnetic field generator and a processor consume more energy. The measurement accuracy affects the surface roughness, on uneven surfaces the device gives significant errors. Contactless moisture makers are multifunctional, devices allow working with wood and other materials: sawdust, chipboard, concrete, MDF, plasterboard.

What moisture meter choose solves the consumer depending on the tasks being solved.