Types of moisture meters - how they work, distinctive features

A moisture meter refers to an electronic instrument used to measure the moisture content as a percentage of the total weight of an object. Such devices help to carry out a qualitative analysis of various materials and most accurately assess their characteristics necessary for further storage and operation for their intended purpose. Therefore, moisture meters are essential to effectively monitor and maintain optimal productivity levels in many industries, including wood, agriculture and construction.

Peculiarities

A moisture meter is a device that measures the percentage of moisture in a gas or solid. Such a device can also be used for working with bulk materials. The well-known hygrometer (determiner of relative air humidity) is a special case of a moisture meter. The purpose of using such devices is varied: they allow you to control the microclimate and comply with technological requirements. Modern moisture measuring instruments are manufactured almost exclusively on an electronic component base.

This technique is especially important in industry, where many types of raw materials, semi-finished and finished products can absorb significant amounts of moisture from the air. It inevitably affects the quality of finished products, their durability, and sometimes even prevents you from getting at least a decent product. Therefore, very strict requirements are imposed on the moisture meter.

Due to the variety of applications, it is impossible to get by with just one version of such a device. And therefore, many varieties of such technology have appeared.

This is interesting: Fuel and oil consumption rates for a tractor - calculation, formula

Wood moisture meter

Instruments for measuring wood moisture are distinguished by measurement methods:

• Conductometric - based on measuring electrical conductivity between two points - electrodes,
• Dielcometric – based on measuring the dielectric constant of a material,
• By definition of the reflectivity of IR radiation,
• By attenuation of microwave radiation when passing through the test sample.

"MEGEON 20502"
The most common are needle (conductometric) and non-contact (dielkometric) moisture meters. Devices that work with microwave and IR radiation are manufactured in a stationary design and are intended for use on wood processing production lines and in the production of particle boards (chipboards).

Basic selection options

Wood moisture meters are available to the mass consumer; different models have their own advantages and disadvantages. To work with lumber, you can limit yourself to a needle moisture meter; when making furniture, working with plywood, MDF and chipboard, it is better to choose a non-contact model. Modern models are compact, have an LCD display, an intuitive interface and are equipped with additional options: temperature measurement, storing results, automatic shutdown, etc.

Features of various types of moisture meters are:

• Needle moisture meters are the cheapest, they are simple and compact, and allow you to quickly take measurements. This type of meters has a significant error when the sample humidity exceeds 30%. During measurements, the integrity of the surface is compromised. The devices are designed to work with chemically untreated lumber.
• Non-contact moisture meters are more expensive, equipped with an electromagnetic field generator and processor, and consume more energy. The measurement accuracy is affected by surface roughness; on uneven surfaces the device produces significant errors. Non-contact moisture meters are multifunctional; the devices allow you to work with wood and other materials: sawdust, chipboard, concrete, MDF, plasterboard.

The consumer decides which moisture meter to choose depending on the tasks being solved.

How to do it yourself?

If necessary, you can make a moisture meter for wood with your own hands. Its circuit includes a dielectric-type sensor. The device will also require a compact generator. Its maximum frequency parameter must be no more than 30 MHz. It is more advisable to select needle contacts for a homemade model. Also, to make a moisture meter for wood with your own hands, you will need a three-channel type microcircuit.

The dielectric constant of the device should be around 3.5 F/m. The microprocessor for the model is selected with a pulse amplifier. Probes are most often used of the tubular type. It is more advisable to select a lowercase display. Compared to text counterparts, it is simpler. The electrodes used in moisture meters are capacitive ones. In turn, the catcher will need to be installed resistive. Lastly, batteries are selected for the model. In this case, you can use regular AA batteries.

Review of popular models

As already written above, the domestic market offers a fairly wide selection of models of moisture meters from Russian and foreign manufacturers. In this section of the article we will talk about some of them.

"Control Hydro Pro"

Appearance of "Condtrol Hydro pro"

This model is a Russian development, its main technical characteristics are given in the table below:

The cost of the model according to Yandex.Market as of the third quarter of 2022 is:

Control Hydro Pro

"EM4806"

Appearance of "EM4806"

This model is produced (Germany), its main technical characteristics are given in the table below:

The cost of the model as of the third quarter of 2022 is 1,500 – 2,000 rubles.

"GMH 3830"

Appearance of "GMH 3830"

The model is produced by GREISINGER electronic GmbH (Germany), its main technical characteristics are given in the table below:

The cost of the model according to Yandex.Market as of the third quarter of 2022 is:

GREISINGER GMH 3830

"SEM DT-125N"

Appearance of "SEM DT-125N"

The moisture meter is made in China, its main technical characteristics are given in the following table:

The cost of the model according to Yandex.Market as of the third quarter of 2022 is:

SEM DT-125N

Opinion about "Valkom AS101"

The presented moisture meter is in great demand in construction safra. First of all, mention should be made of a high-quality generator, which is installed with a frequency of 33 MHz. In this case, the sensor is of a dielectric type. The contacts, in turn, are needle-shaped. If you believe the reviews of experts, the measurement accuracy of the model is high.

It can be used for parquet and panels. The minimum permissible temperature of the device is 0 degrees. The resolution indicator is 1 pH. The catcher itself in the device is installed of a resistive type. The microprocessor is used with a switching amplifier. The maximum humidity threshold of the device is at 40%. You can buy this moisture meter for only 1,400 rubles.

Non-contact devices

The dielcometric apparatus tests the material at a certain distance without violating its integrity. Its sensors are mounted on the working surface, replacing probes. High accuracy is ensured when quickly examining a sample, and it is also possible to store the research results in memory.

More expensive models allow scanning at a depth of 50 mm. It is advisable to use the device when it is necessary to perform a calculation based on the lower threshold of a parameter.

It also has the option to evaluate the temperature and humidity of the environment. This device is indispensable when analyzing solid and dense workpieces.

Devices for determining moisture EMCO MP500

This moisture meter is equipped with a dielcometric type sensor. If you believe customer reviews, the resolution of the device is quite high. The generator itself is used at 22 MHz. According to the documentation, the maximum permissible temperature is 40 degrees. The display in the device is of text type.

The batteries are 1 mAh, so they last a long time. In this case, the catcher is provided by the manufacturer as a resistive type. If you believe the reviews of experts, then problems with determining the importance of wood chips do not arise. The maximum measuring depth is 10 mm. The user can purchase the presented moisture meter for 1,400 rubles.

Laboratory and portable moisture meters

Grain moisture is measured in laboratory and field conditions; according to this, the entire variety of moisture analyzers is divided into laboratory and portable devices. But for moisture meters of any type, the most important characteristic is the accuracy of measurements.

The greatest accuracy in measuring grain moisture is provided by analysis based on the use of special drying ovens. To carry it out, a grain sample, previously ground, is dried for 40 minutes at a temperature of 130 degrees. The sample is then cooled and weighed. The difference between the mass of the sample before and after drying is the basis for calculating the percentage of moisture. But this method is only suitable for laboratory conditions.

Portable (portable) moisture meters for express analysis work based on measuring either the dielectric constant of a substance (dielectric moisture meters) or on the absorption of acoustic or electromagnetic vibrations by a grain sample (flow moisture meters).

This is interesting: Tractors T-150 and T-150 K - characteristics, scope of application

Reviews about "Valkom M804"

This wood moisture meter mostly receives good reviews. The main advantage of the model lies in its compactness. If we talk about design features, it is important to note that it uses probe contacts. There are two sensors directly in the housing. Thus, the measurement accuracy is quite high.

The manufacturer provides the probe in the device with a tubular type. The resolution of the device fluctuates around 1.3 pH. The maximum humidity threshold, according to the documentation for the moisture meter, is 35%. Today you can buy this model for 2 thousand rubles.

Best models

If you need to measure grain moisture, the Fauna-M model is suitable. This is a microprocessor device designed for oilseeds and grains. “Fauna-M” can be used during harvesting, and when monitoring the quality of harvested grain, and during storage, and during express analyzes during processing. The device operates in a dielectric method, and the measurement results are displayed on an alphanumeric display with backlight. There is a sensor that determines the temperature of the grains; There is also a setting that compensates for errors caused by temperature changes.

By adjusting the calibration of the device, you can adapt it to a specific type of grain crop. Even in the most difficult cases, the measurement error will not exceed 1.5%. The system is designed to work with :

• wheat;
• soybeans;
• peas;
• sunflower;
• rapeseed;
• triticale;
• mustard;
• flax;
• 8 more crops;
• optionally with chickpeas, safflower and other grain plants.

Testo 606-1 is a moisture meter for measuring the water content in wood and building materials. The model is included in the federal state register. Its memory contains characteristic curves for various types of controlled substances and wood species. You can successfully explore:

• beech;
• cement beacons;
• maple;
• concrete mixture;
• brickwork;
• pine;
• plaster;
• larch;
• mortar;
• spruce.

Thanks to the Hold option, reading measurements is simplified. The moisture meter from Testo lights up the screen and performs self-diagnosis if necessary. Other features worth noting:

• cover for protected storage;
• carrying strap;
• proprietary calibration protocol included;
• weight 0.09 kg;
• dimensions 0.119x0.046x0.025 m;
• error no more than 1%;
• measurement every second.

Condtrol Hydro-Tec is also an excellent moisture meter for working with wood and concrete. The device works very quickly. The design allows you to set the moisture content in the range of 2-65% in layers up to 0.02 m deep. The built-in sample library contains 20 types of wood, but not randomly, but divided into 9 groups. The manufacturer claims that Hydro-Tec is professional grade.

Therefore, it is readily used in woodworking, furniture, parquet, molding, window and door industries. The company warranty is given for 2 years. The device is included in the federal register. Requires a pair of AAA batteries to operate. The measurement takes no more than 1 second; and the relative air humidity during operation should not exceed 85%, permissible temperatures - 5-40 degrees above zero.

For wood and grain, Gann Hydromette Compact from Germany can be used. The German product can also work with sawn wood, fiber and particle boards no thicker than 0.025 m, gypsum and plaster. This needle-type moisture meter allows you to take into account the temperature of the material according to the table included in the delivery set. The moisture content of the plaster is indicated as a percentage of the dry mass. A 9 V dry cell or a rechargeable battery is used for power supply.

Probe devices

Probe moisture meters for wood are mainly manufactured by . If you believe the opinion of experts, their relative error parameter is extremely low. Generators in devices are used with a frequency of 20 MHz. The catchers themselves are installed of the resistive type. The minimum humidity threshold for models does not exceed 5%. In turn, the resolution of the devices is at the level of 1 pH. Displays of moisture meters are often used in line type. Some modifications are equipped with thermometers. The calibration function in devices is quite rare. You can find a model of this type on the market for 2 thousand rubles.

Testing and Calibration

The simplest option is to wrap the device in a wet cloth and then in a plastic bag. Within an hour, in a tightly closed bag, the humidity will reach 96%. The readings will stop changing. If this does not happen or the device gives incorrect readings, it cannot be trusted. More precise adjustments can be made using table salt. It is poured into a saucer and diluted with water until completely dissolved.

The solution must have a high concentration. Then the saucer is placed in a tightly locked sealed box. A moisture meter is also placed there. After 8 hours the humidity will reach 75%. As soon as this happens, the device is removed and this value is set as quickly as possible.

To learn how to choose the right moisture meter for wood, see below.

Description of "Ectech MO280"

This portable moisture meter features a protected housing. It uses a low-frequency sensor. In turn, the contacts are needle-shaped. The presented copy has a calibration function. The ambient temperature can be determined using this device. It is also important to mention the high resolution of the model.

The measurement accuracy in this case is 0.3%. The maximum humidity threshold allowed by the model is 45%. The microprocessor is provided by the manufacturer with an operational amplifier. Thus, data processing does not take much time. The memory of the presented modification is enough to make more than 20 thousand measurements. You can buy this moisture meter in a store for 1,300 rubles.

TFA 45.2033

TFA 45.2033

Country of origin: Germany. The mechanical type hygrometer is made in the shape of a circle. The case has a brass ring and an informative dial, which is divided into comfort zones. Measuring range: humidity from 0 to 100%, temperature from -15 to +55C°. The device has a wall mount.

Advantages:

• low cost;
• ease of operation;
• wall mounting option.

Main disadvantage:

• When direct sunlight hits the device, it gives readings with a large error.

Harvia SAC92200

Harvia SAC92200

Country of origin: Finland. The body of the model is made of wood in eco-style. It has the shape of a rounded square, into which a clear dial is inserted, the measurement step of which is 10 units. The body material is birch. The model has a hair operating principle. Measuring range: pressure from 0 to 100%, temperature - from -15 to +55C° .

Advantages:

• nice design;
• low cost;
• high accuracy;
• ease of operation.

Main disadvantage:

• long period of response to changes in air humidity.

Do you need a function to remember results?

The function of storing results is very important for a moisture meter, as it greatly simplifies working with it. But the most important thing is that this function provides a number of other useful features.

Firstly, based on this function, it is possible to calculate the average value based on the results of measurements. Even with the simplest moisture meter, you need to take several measurements in different places in the material. This is indicated in the instructions and without such manipulation the result cannot be considered correct. After all measurements have been completed, you need to calculate the average value, which, in principle, is not difficult. However, when we are talking about dozens of measurements per day, the possibility of automatic calculation turns out to be extremely useful.

Kinds

The market for such devices is large: from small compact moisture meters to huge devices with many different functions. Let's look at the two most popular types.

• Needle (contact) Designed for extremely accurate measurement of the moisture level of various lumber and wood products. Determination of humidity occurs by measuring and converting the electrical resistance of the material under study into a percentage using the conductometric method.
• Contactless. Designed for high-precision determination of the moisture level of wood products using the dielcometric method. The measurement takes place in several stages: the type of species is set on the device, it is leaned against the surface of the wood, a button is pressed and the measurement result is displayed on the indicator.