Rules for use and the operating principle of moisture meters

In the construction industry, moisture meters are indispensable instruments, particularly when handling concrete. By assisting in the determination of the moisture content of different materials, these tools guarantee that building projects adhere to safety and quality standards. Knowing how to use moisture meters and the fundamentals of how they work can help you avoid future structural problems and save time and money.

It’s simple to use a moisture meter, but in order to obtain accurate readings, you must adhere to certain instructions. First, make sure the device is calibrated correctly in accordance with the guidelines provided by the manufacturer. There are various varieties of moisture meters that are suitable for various materials and circumstances, such as pin-type and pinless models. Reliable results depend on the type you choose for your project.

A moisture meter’s basic method of operation is to measure the material’s electrical resistance or dielectric characteristics. Electrical resistance is used by pin-type meters, which measure the resistance to an electrical current by inserting pins into the material. Conversely, pinless meters do not penetrate the material; instead, they measure moisture content using electromagnetic waves. While both approaches offer insightful information, being aware of their distinctions aids in selecting the best instrument for a given job.

Concrete and other materials can be kept in ideal condition for construction work by routinely checking their moisture content. Cracking, warping, and other structural problems can be avoided with proper moisture control. Construction professionals can maintain high standards and improve project outcomes by using moisture meters effectively.

Rule Explanation
Calibration Always calibrate the moisture meter before use to ensure accurate readings.
Surface Preparation Ensure the concrete surface is clean and free of debris for reliable measurements.
Proper Contact Place the meter firmly against the concrete for accurate moisture readings.
Consistent Pressure Apply consistent pressure when taking multiple readings to maintain accuracy.
Reading Interpretation Understand how to interpret the readings based on the specific moisture meter"s guidelines.
Operating Principle Moisture meters work by measuring the electrical resistance or dielectric properties of the concrete.

How the device works?

All contemporary electronic moisture meters operate on a similar principle, independent of design, functional purpose, measurement accuracy, and other factors.

The principle of high-frequency oscillations operates when the needle probe makes contact with the test material in the contactless flask, or when the probe approaches it. These oscillations are distributed throughout the solid’s structure and directed towards the closest plane.

After assessing the level of humidity in the test product, the device’s conductive components send pulse signals to the actuator, which reads the data and then sends it to the electronic unit in the form of digitally encrypted commands.

The electronic unit’s built-in microprocessor reads the program code, decodes the data, and displays the results on a multifunctional liquid crystal display as a percentage of moisture relative to the volume of wood or other material.

To determine whether the material needs to be refined or laid in the structure, the moisture meter’s memory can store the readings that are obtained on the screens of common appliances. Alternatively, the readings can be manually transferred to the relevant statement.

Professional devices come with a wireless data transmission module that makes it simple to store measurement results in a mobile device’s or PC’s memory and integrate them into engineering computation programs.

Preparation for operation and setup

The following algorithm must be used as part of several preparatory steps before beginning to use the moisture meter to measure the percentage of water molecules in bulk solids or the structure of solids:

  • When using a new device, it may be necessary to assemble it after removing it from the packaging, in accordance with the manual attached to the product unit.
  • Installing batteries in a special compartment on the back of the device.
  • Checking the battery charge level, if necessary, replenishing it by connecting the device adapter to the network.
  • Setting the desired operating mode on the moisture meter, since most multifunctional devices have a function for switching the type of materials being tested.
  • Verifying the device using a reference moisture meter, hygrometer or other auxiliary equipment that shows the actual moisture content of the material by comparing these indicators with reference parameters.
  • If the verification shows the presence of an error beyond the maximum permissible values, the user must also calibrate the moisture meter by forcibly adjusting the measured moisture content of wood, concrete, brick, soil or other materials with reference values ​​identified previously.

The lack of calibration or verification will prevent the user from getting accurate information about the material’s humidity, which could have unfavorable effects.

A verification certificate issued by specialized companies authorized to make adjustments to metrological devices of that category should always be attached to professional equipment.

How to use the unit correctly?

Even though the working principle of all moisture meters is similar, the algorithms for each of these types of devices may vary slightly because they are made for different materials.

The operating instructions for all current electronic moisture meters made for different types of materials are listed below, along with a description of the finer points to ensure the most accurate and genuine indicators.

Instructions for building materials

Building material moisture meters are straightforwardly constructed, and their use is outlined in the process chart below, which varies based on the kind of stone product.

Concrete

  • The structure to be tested must be dust-free, free of oil from the formwork and dry.
  • The device is turned on and placed against the concrete plane.
  • When ensuring contact, it is important that both probes are securely attached to the plane of the pylon, wall, column or ceiling.
  • The readings on the screen are recorded in the log.
  • It is recommended to take several measurements at the bottom of the structure, then along its length, in increments of up to 500–800 mm.
  • Based on the test results, it is necessary to find the arithmetic mean between all measurements, as well as determine the maximum and minimum values.

Brick

  • 5–10 samples are selected from a batch of small-piece stone materials, each of which must be tested from the spoon and from the side of the bed.
  • If the humidity is determined for finished masonry, it is recommended to wait for some time after its construction until the cement-sand mortar has completely gained strength, since excess moisture is absorbed into the brick, which causes a failure in reliable results.
  • The method for determining the moisture content of bricks depends on the type and design of the moisture meter. For needle moisture meters, the measurement and recording scheme is little different from concrete. In the case of using a moisture meter with a spherical flask, the technology is called contactless, and the device is brought as close as possible to the plane of the brick, after which the metal plates inside the sphere begin to deform and transmit information to the actuator.

Paving slabs

  • The same moisture meters are used for paving slabs as for concrete, because, as a rule, this element of exterior decoration consists of the same basic components.
  • During the production process, it is recommended to analyze the moisture level 3-4 times, as the product hardens, every 4-5 days.
  • Humidity measurements are stopped when its percentage content drops to 10% – 15%, which indicates an almost complete set of strength of the material.
  • If you purchase tiles at a retail outlet, you should check their moisture level from both the front, end and back sides. This is due to the heterogeneous ingredients, the peculiarities of laying liquid concrete into the tile composition, as well as the possible presence of glaze on the front side, which will not allow you to get a completely objective result.
  • When buying a large batch, it is recommended to test at least 10 samples of tiles, and then compare the indicators with each other.

When it comes to determining these parameters in concrete, brick, paving slabs, and some other products that are frequently encountered in practice, mode switching buttons are typically found on the majority of professional and household moisture meters that are made to measure moisture in stone building materials.

Devices for wood

Wood moisture meters are among the most widely used metrological equipment types available today. These devices come in two varieties in real life: needle and contactless (induction). To operate either of them, there are a few basic yet crucial guidelines that must be followed:

  1. Needle moisture meters:
  2. After calibration and preparation for work, the device is turned on, the desired type of wood is configured on the multifunctional display, using the control panel keys.
  3. The moisture meter is leaned against the tree with 2 powerful needle probes, strictly perpendicular to the plane of the bar.
  4. The user forcefully plunges short and sharp spikes into the structure of the wood, after which he quickly removes the device.
  5. The screen displays the moisture content of the wood.
  6. The procedure is repeated for 2 side faces and for the end of the board or beam.
  7. Induction (contactless) moisture meters:
  8. The device is held in a horizontal position, turned on.
  9. The master carefully places the moisture meter on the surface of the bar or board.
  10. The screen instantly displays the humidity of the material.
  11. As the device moves along the product, the readings on the screen change.
  12. Professional devices have a button for setting minimum and maximum values. As the test is carried out, the moisture meter automatically records these values, after which it provides the user with ready-made statistical data.

Customers should be advised by experts that because wood is an exceptionally heterogeneous organic material, different products from the same batch may have varying moisture content percentages. In this regard, testing multiple samples from the batch at once is advised when determining these parameters.

For bulk materials

Two types of moisture meters are also used to measure the amount of moisture in bulk materials: those with steel rod probes or those in containers. The following guidelines and considerations are followed when utilizing these devices:

  1. Tools with Probes:
  2. After setup, verification and calibration, the device is put into operation.
  3. Needle probes are immersed in the lower part of the embankment, to a depth of up to 300 mm.
  4. The user carefully moves the device upwards, along the natural slope of the embankment,
  5. As the moisture meter moves along the embankment, the readings on the indicator change, after which the professional moisture meter determines the average reliable moisture value.
  6. The operation is repeated from different sides of the embankment, which is especially important if the bulk material was stored in the open air, and the sun hit it from different sides.
  7. All readings are recorded in the statement, compared, after which the average moisture parameter of the bulk material is displayed.
  8. Container type:
  9. The inner cavity of the container is cleaned and dried.
  10. Up to 100 – 200 g of bulk material samples are poured into the container.
  11. The container is closed with a lid.
  12. The device is turned on and, after 10-15 seconds, it gives an accurate indicator of the percentage of moisture in the bulk material.
  13. A second sample from another area of ​​the embankment is poured into the container, and the procedure is repeated.
  14. To obtain accurate reliable readings, it is recommended to conduct up to 3-5 iterations, after which calculate the average steam meter.

It should be noted that bulk materials have a higher filtration coefficient. As a result, the percentage of moisture in the lower portion of the embankment can be two to three times higher than these indicators in the upper part. Therefore, it is advised to take measurements over the course of three to five iterations in order to obtain a reliable result, and to calculate average values afterwards.

For food products

Food products’ moisture content is measured for both semi-finished and finished goods, as well as for individual ingredients used in manufacturing.

Food product specific moisture meters are constructed from safe materials, and the following detailed instructions should be followed when using them:

  • The food sample to be tested is separated from the total mass to take measurements and eliminate the risk of contamination.
  • The moisture meter is set up according to the criterion of the boundary parameters of humidity, or according to the type of food product, if the user purchases a device designed exclusively for organic food products.
  • The needles are immersed in the middle of the sample, after which the measurement is made near its upper edge.
  • The indicators are compared with each other, compared with the quality certificate or recommendations for a specific product.
  • To obtain accurate results, it is recommended to take measurements for 2 – 3 samples from each batch.
  • Before starting the tests, do not wet or, conversely, dry the product.

These devices typically have an extremely small error rate—no more than 2%—because even small mistakes in humidity measurement can lead to improper storage conditions, which deteriorate food quality and encourage the growth of mold, pathogenic bacteria, and rotting goods.

For soil and ground

In agriculture, soil moisture meters are used extensively when a farmer or machine operator needs to precisely determine when to water or dry the soil. They are also used in construction, where they are used to measure the amount of moisture in the soil base beneath the fifth building.

These devices operate in accordance with the process diagram that follows, while also accounting for several significant quirks:

  • The moisture meter is prepared for work.
  • On a plot of land, or within the building site, the points for which measurements will be made are determined.
  • The test areas of the base are cleared of all organic inclusions – weeds, plant roots.
  • The device is turned on, and the probe is immersed in the body of the soil base to the maximum permissible depth.
  • If it is required to determine not the moisture content of crops, but the water content in the soil base for construction, the topsoil is completely removed in the measurement area.
  • For each point, one iteration is carried out after which all indicators are recorded in the table.
  • If the discrepancies in the degree of humidity exceed 10%, it is recommended to additionally select zones with a high water content and more dry soils, since their composition can be aquifers that need to be examined separately.
  • After the measurements are carried out, the minimum, maximum and average moisture indicator of the soil base is calculated, and the data is transmitted to the engineer for the preparation of the working project.

A thorough analysis of the chemical makeup of water, the existence of acidic or alkaline substances, an assessment of the area’s potential for flooding, which will aid the engineer in creating a drainage plan, and the efficiency of the construction water supply system when pit excerpts are present are all possible with a variety of specialized equipment.

Difficulties in application

Novice users of household moisture meters may make several mistakes that have detrimental effects, such as determining the moisture content level of food items, building materials, and soil bases incorrectly.

In order to mitigate the possibility of procuring substandard materials or to eradicate additional challenges, the following are the most frequent mistakes made by users when using moisture meters incorrectly:

  • Using a certain modification of a moisture meter for other purposes – these electronic devices are classified by area of ​​application, and for each type of building material it is recommended to use a specialized device.
  • Lack of verification or calibration of the moisture meter – when taking measurements, the user receives unreliable results that do not allow an accurate assessment of the condition of solid or bulk building material, food product or soil base, which entails negative consequences.
  • Too much pressure on the needle probes when immersing the device in wood – there is an increased risk of their plastic deformation, breakage and failure of the device.
  • Carrying out humidity measurements only in one place on the surface of the building structure – considering that concrete or wood are heterogeneous materials, it is necessary to measure the percentage of moisture in them in several places at once, and then calculate the arithmetic mean, taking into account the minimum and maximum values.
  • Incorrect selection of the mode of the universal multifunctional moisture meter – neglecting the adjustment of the sensitivity and the permissible limit of material moisture leads to an increased risk of obtaining unreliable readings, or to a failure of the device settings.
  • Carrying out measurements with discharged batteries – the moisture meter cannot correctly read the information, since the oscillation frequency is insufficient to analyze the moisture content of the tested product.

It is advised to read the documentation that comes with the device before using it to ensure that all potential errors have been ruled out. You should also view a number of videos on popular Internet channels that feature lessons and master classes taught by professionals and experts, who frequently share them with beginners.

Rules and recommendations for use

Every moisture meter has a service life and eventually experiences physical depreciation. It is advised to carry out the following basic preventive procedures or minor repairs on metrological equipment in order to ensure that this does not happen too quickly and that the device serves for many years without the need to replace it or carry out major repairs:

  • Moisture meters should be used only for its intended purpose.
  • It is recommended to study the instructions before starting operation.
  • Devices must undergo periodic verification, calibration and general diagnostics for timely detection of failures and errors.
  • Probes and analyzers must always be dedusted, cleaned of dirt, grease and moisture, in order to avoid loss of sensitivity, as well as oxidation of metal conductive parts.
  • It is recommended to recharge the battery only after it is completely discharged, since such a cycle will ensure long-term operation of the battery without rapid loss of capacity.
  • Batteries for amateur devices should be stored for a long period, separately from the moisture meter itself.
  • It is not recommended to measure humidity at sub-zero temperatures, since the device is exposed to negative atmospheric influences, and, from the point of view of metrology, such a procedure does not make sense, because the water is in a crystallized state.
  • For the same reasons, measurements should not be taken in heavy rain, since the moisture meter will show too high and unreliable water content in the test material.
  • It is forbidden to drop the device, step on it or subject it to other impacts, since this will cause not only a failure in its settings, but also a complete breakdown of the equipment.

It should be remembered that the moisture meter’s brand, place of manufacture, and year of manufacture guarantee its quality, as do the favorable comments left by pleased customers regarding a particular product modification on third-party online forums.

Useful video

Additional details regarding how video devices work:

Anyone working with concrete has to know how to use and operate moisture meters properly. In order to achieve the best strength and durability, the concrete mixture needs to have the proper amount of moisture, which is what these devices help to ensure. A more dependable and long-lasting structure can be achieved by routinely checking moisture levels, which can help prevent possible problems like cracks and structural weaknesses.

There are several varieties of moisture meters, and each is appropriate for a particular use. To obtain accurate readings, it’s crucial to adhere to the manufacturer’s instructions whether using a pin-type or pinless meter. To get accurate data and make defensible decisions regarding the concrete curing process, measurement techniques must be consistent.

Moisture meter calibration on a regular basis is also crucial. These devices may deviate from their initial settings over time, producing readings that are not accurate. It is possible to make sure that the information you gather is accurate and reliable by routinely calibrating your moisture meter. The quality of your concrete work can be significantly improved by taking this simple step.

To sum up, moisture meters are very useful instruments in the building sector. They supply vital information about moisture levels, which aids in preserving the integrity of concrete structures. You can steer clear of common pitfalls and guarantee the highest caliber of results for your concrete projects by using these devices correctly and maintaining them.

In order to guarantee the longevity and quality of concrete structures, moisture meters are vital instruments in the construction industry. They function by determining the amount of moisture in concrete, which helps stop issues like weakening, cracking, and the growth of mold. To accurately use a moisture meter, one must know how to calibrate the instrument, take precise readings at various intervals, and interpret the data to make decisions regarding the drying and curing procedures. Builders can make sure their concrete projects meet industry standards and function well over time by adhering to these guidelines.

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Andrey Ivanov

Experienced civil engineer with more than 20 years of experience. Specializing in the construction of industrial and civil facilities. Author of many publications in professional journals.

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