The process of calibration and verification of moisture meters

Comprehending the concrete’s moisture content is essential to guaranteeing the longevity and excellence of building endeavors. In order to help engineers and builders make informed decisions, moisture meters are crucial instruments for measuring the moisture content of concrete. However, these meters need to go through a procedure called calibration and verification in order to give accurate readings.

The process of calibrating a moisture meter involves making adjustments to guarantee that its readings are precise and reliable. In order to enable the device to provide accurate measurements, this entails comparing it to a recognized standard or reference. Because usage, wear and tear, and environmental factors can all affect a meter’s accuracy over time, regular calibration is essential.

On the other hand, verification is the process of making sure the moisture meter keeps working properly even after calibration. To make sure the device maintains its accuracy, it entails comparing the readings it takes with known values. Depending on how frequently the meter is used and the conditions it is exposed to, verification is usually done at different intervals.

The maintenance of moisture meter reliability requires both calibration and verification. Construction workers can stay compliant with industry standards, prevent expensive errors, and guarantee structural integrity by making sure these devices are operating properly. This procedure improves the general success of construction projects while also protecting the concrete’s quality.

Step	Description
Initial Setup	Ensure the moisture meter is clean and in good condition.
Standard Calibration	Use a standard material with known moisture content to calibrate the meter.
Verification	Compare the meter"s readings with the standard material to check accuracy.
Adjustment	If the readings are off, adjust the meter settings according to the manufacturer"s instructions.
Re-Verification	Test the meter again with the standard material to ensure accurate readings.
Regular Checks	Periodically verify and calibrate the meter to maintain accuracy.

What is it?

Moisture meter calibration consists of a series of required control operations that must be performed in a precise order. These procedures include forcing the actuator and the electronic unit’s indicator to be adjusted.

The actual moisture content of the test sample is displayed on a reference metrological device during calibration. The moisture meter is then adjusted until the previously determined reference value is reached on the indicator, at which point the settings are saved.

Based on the calibration results, the device’s error and error risk are decreased over a certain amount of time, the length of which is determined by the assembly quality and factory tolerances.

Calibration is an ongoing process that starts as soon as issues with the primary settings’ failure are detected.

What is the test for?

Moisture meter calibration is a regular, required control and commissioning procedure that yields the following outcomes:

• Achieving the ultimate accuracy of measurements of the percentage of moisture in any solid or bulk materials.
• Reducing the risk of errors and inaccuracies when measuring humidity.
• Accurate determination of properties and the possibility of unimpeded use of test samples of materials.
• Possibility of certification of materials to obtain relevant documents and identify optimal technical characteristics.
• Satisfaction with the requirements of the standards and restrictions for metrological equipment in force in our country.

When calibrating professional equipment, it’s best to do so only at authorized dealer centers or testing labs that hold the required licenses and can provide the user with a certificate attesting to the device’s complete compliance with the most recent standards.

How the process goes?

The following production and control activities are implied by the process map that is used to calibrate moisture meters.

For concrete

Guidelines and a flow diagram for this process:

• If there is an error in measurements, the foreman, knowing the readings on the reference device, makes at least 3 – 5 measurements for the same reinforced concrete structure using it.
• The places where the measurements were taken are marked with a marker, the readings are written down in a special sheet.
• The device being calibrated is applied to the same place where the measurement was previously taken with a standard device.
• The calculated indicators are determined, taking into account the error, after which the display lock key located on the control panel is held down.
• Under the lock key there are also buttons with arrows, pressing which changes the value on the screen by 0.1%.
• By repeatedly pressing the arrow keys, the humidity value is set, identical to the results that were measured using a reference moisture meter.
• The obtained data is stored in the device"s memory.

Bricks

The general calibration scheme and the concrete device settings are nearly identical:

1. To carry out accurate measurements, it is necessary that the brick is not water-saturated after immersion in an aqueous medium.
2. The obtained indicators should be compared with the data from the results of measuring the bed, edge and spoon of the brick, since the moisture content in them may differ.
3. It is recommended to separately calibrate the device when determining the error in the composition of the masonry, and then make a control measurement for individual bricks from the same batch on a pallet.

Paving slabs

The calibration process is essentially the same as when a moisture meter is set up for a reinforced concrete structure.

The primary distinction is that the initial verification, which comes before the calibration, needs to be done strictly from either the front or the back of the paving slabs, depending on which side they are processed to a different degree.

Wood

• Calibration is performed with 3 iterations.
• The general scheme for setting the actual parameters relative to the percentage of moisture content displayed on the LCD screen is identical to the previous schemes.
• After checking the device from the end of the bar, the moisture meter is calibrated to achieve the permissible error.
• Next, the verification is repeated for the side face of the wooden product.
• At the final stage, the wooden bar is verified for the second perpendicular face.
• For each new iteration, if there is a discrepancy, the electronic device is calibrated.

For bulk materials

• Calibration should be performed only if the verification showed a discrepancy of more than 3%.
• It is recommended to perform calibration step by step – no more than 0.5% difference in moisture, followed by repeated verification in several places at once.
• Calibration and verification must be carried out strictly on the same day, since loose soils tend to quickly become saturated with moisture or, conversely, dry out, due to increased porosity.

For food products

• If the verification showed a discrepancy, you should pour grain or other products into the reference flask, then set the actual humidity indicators while holding the lock key and switching settings.
• After calibration, you must load a second batch of product from the same delivery with similar characteristics into the receiving bin and conduct a second iteration of verification with subsequent minor calibration.
• If significant discrepancies in error are detected between different iterations, you must empty the bin and clean the analyzers from plaque or other traces of contamination.
• A fully calibrated device is subject to repeated verification, which should not show discrepancies for different iterations of more than 1%.

For soil and soil

• Calibration is carried out exclusively in dry and cloudy weather to prevent rapid evaporation of moisture or water saturation of the soil.
• Calibration implies full compliance of the results of real measurements with the reference indicators for each zone where the moisture meter was verified.
• Considering the heterogeneity of the structure of the soil base, it is recommended to calibrate several times for different zones of the soil base under the construction site of the future real estate object.

It should be taken into account that each moisture meter from different manufacturers may have different calibration schemes, depending on its structure and functionality.

In this sense, it is advised to read the device’s operating manual and watch a number of professional video tutorials and master classes—which they frequently share with other users of the same device on the network—in order to prevent mistakes when executing this algorithm.

Verification and its differences from calibration

Verification does not require adjusting the moisture meter, in contrast to calibration. As part of this control measure, the precise ratio of the moisture content percentage is calculated by comparing the device’s actual readings with reference samples.

Verification is therefore a preventive measure, the results of which indicate whether calibration or continued operation of serviceable and adjusted equipment is necessary to ensure that its functionality is not interfered with by outside parties.

Depending on the device category and the conditions for official verification certificates for expert organizations to be available, verification should be done at least once every three, six, or twelve months.

Why is it carried out?

In order to accomplish the following objectives, calibration and moisture meter verification are essential steps that must be taken:

• Determining the accuracy of measurements of the percentage of moisture content in solid or bulk materials.
• Calculating the error that the device achieves when taking measurements.
• Making a decision on the need to calibrate an electronic device.
• Detection of other faults and the need for a complete diagnosis of the moisture meter.
• For preventive purposes, to obtain the next verification certificate – for professional equipment, which is a mandatory requirement of GOST.

The test results may be canceled and not be taken into consideration by the State Acceptance Commission or other authorities to whom they are provided upon request if the expert organization lacks a verification certificate for professional metrological equipment.

How often?

The process of verifying moisture meters is done in compliance with GOST regulations, expert organization internal policies, and manufacturer recommendations. The following values typically represent the average time interval between consecutive verifications:

• At each suspicion of failures, errors or breakdown of the device.
• In the event of discrepancies between analogs, if they are accidentally detected, for example, if the client checked the moisture content of wood with his moisture meter.
• For household appliances that are used occasionally – once every 12 months.
• For household moisture meters that are often used by small suppliers or retail outlets – once every 6 months.
• For professional equipment – every 3 – 6 months, depending on the materials being tested and the frequency of use of the moisture meter.

It is advised to depart from the above-described regulations and perform verification more frequently, such as once a month, if the device is used frequently and daily. This ensures measurement accuracy and reduces the possibility of errors that could have a detrimental impact on the material’s quality and the structure’s dependability.

Where it should be carried out?

Any of the following locations should be used for the verification of moisture meters produced by duly registered manufacturers with certificates and their own retail stores:

• In service centers that are authorized dealers of the brand, provided that they have reference equipment for verification.
• For professional metrological devices of the category in question – in specialized laboratories that are equipped with modern testing equipment and have their own SRO certificates for full control of the device.
• In the conditions of a construction site or at home, if you have a previously verified and calibrated moisture meter with similar characteristics, or a high-precision hygrometer, but it gives less accurate readings, since not all models can measure the percentage of moisture in solids, but determine it in the surrounding air.

It should be noted that only specialized businesses with the authority to issue official certified documents with blue seals can verify professional moisture meters, which are used to draft and obtain official expert opinions.

Rules for conducting

Verification is done according to the following guidelines and specifics, depending on the kind of moisture meters, their structural characteristics, working principle, device category, and suggested application range.

1. For building materials:
2. Using a reference device, or in laboratory conditions, the actual moisture content of the building structure sample is measured.
3. The moisture meter is turned on.
4. The device probes are applied to the surface of the structure.
5. The working indicators on the moisture meter are identified.
6. The operation is repeated 3-5 times in different places of the same building structure.
7. From the obtained data, the minimum, maximum and average indicators are identified.
8. The obtained data are compared with the reference value.
9. The measurement error of the device is determined, which, according to GOST rules, is allowed within the range of 2% to 3%.
10. If the measurement error is within the permissible values, the device can be used in normal mode.
11. If the error is outside the permissible values, the moisture meter requires calibration.
12. For bulk materials:
13. Comparison of actual indicators with reference ones is performed using one of two basic methods.
14. If the moisture meter has a loading hopper for bulk materials, these ingredients are poured there after identifying the degree of moisture with a reference device.
15. In the case of using a contact moisture meter with probes, the rods are immersed in the bulk structure 5 – 10 times, after which they are slowly moved upward to fix the boundary and average indicators.
16. Theoretical comparison of measured and reference indicators is performed using the same method as in the previous case.
17. For wood:
18. To perform verification, it is required that the natural moisture content of the wood is at least 5%.
19. It is recommended to use a verified and calibrated moisture meter of the same brand as a standard.
20. The end and side faces of the test block are marked with a marker indicating the iteration number – from 1 to 5 – 10 units.
21. The pointed probes of the reference moisture meter are stuck to a shallow depth into the structure of the wood, and the expert records the obtained parameters.
22. After all the reference, or real indicators are recorded, the procedure is repeated for the device being verified.
23. The difference between the indicators for each iteration is calculated, after which the average arithmetic error is determined.
24. If the obtained discrepancies exceed the value of 2% to 3%, the device must be calibrated
25. For food products:
26. Verification is carried out in two ways.
27. First of all, each food product that has a certificate must initially be tested in special laboratories for chemical composition and natural moisture.
28. The second stage is to determine the actual content of water vapor using a reference device, or using a hygrometer if the product is in a closed space for a long time, for example, in a grain storage silo.
29. The data obtained as a result of the analysis is recorded in a journal.
30. The product is placed in the receiving hopper of the moisture meter, after which the user determines the degree of its moisture content.
31. The indicators are compared, after which the expert makes a decision on the need to adjust the moisture meter, or on successful verification.
32. For soil:
33. It should be taken into account that the number of iterations directly depends on the heterogeneity of the soil cover.
34. For clay soils, it is necessary to carry out at least 8 – 10 reference measurements, while for soil that has an increased filtration coefficient, that is, sandy loam or sand of different sizes, no more than 3 – 5 iterations are sufficient.
35. For each reference zone, two measurements are taken – near the soil surface, and also after immersing the probes of the device to the maximum permissible depths to increase the scanning area.
36. It is recommended to carry out work in cloudy weather and in the summer, in the absence of a flood period in the spring, to exclude incorrect parameters during verification.
37. The final error according to the results of the measurement combination should be no more than 4%, taking into account the heterogeneity of the composition of the soil. As for the sifted sand, the error should be less – do not exceed 3%.

Moisture meter calibration always entails internal structural modification and a partial departure from the device’s preprogrammed algorithm.

In this sense, an operation of this kind is performed not only in the event that minute variations between the true causes and the reference ones are identified, but also in the event that these parameters stay within the allowable error range.

What is issued after?

Following manufacturer-approved center verification, a certificate attesting to the device’s compliance with the technical specifications of the products listed in the quality passport is issued.

The user obtains a state-issued certificate that permits him to use this metrology equipment for commercial purposes if the verification of a professional moisture meter is completed by specialized expert organizations with specific reference devices.

The device’s owner can be certain that the settings are correct if verification and subsequent calibration are done by hand, should the need arise, but it is not possible to verify these control measures using any paperwork.

Why is it important to carry out measures on time?

The most crucial step in the production process is the calibration and verification of a moisture meter, which is done strictly in compliance with regulations. For the following reasons, these control measures are the most crucial part of the metrological device’s technical maintenance:

• The device will always show accurate results of parameter measurements, humidity of solids or bulk materials.
• The moisture meter can be used as laboratory equipment to obtain expert results.
• The master or owner of the facility will receive reliable information about the possibility of laying the material in the structure or the need to refine it to acceptable parameters.
• The device will meet the requirements of international or federal standards.
• During calibration, other moisture meter malfunctions can be additionally identified, which will allow timely repair of the equipment.

The accuracy with which you can ascertain the percentage of water vapor in a solid or building structure is compromised by an uncalibrated and unverified moisture meter. This can lead to significant issues with future structure durability and reliability, as well as difficulties setting up a drainage system to keep the facility from flooding during flood conditions.

Useful video

Regarding the video’s configuration of moisture meters:

In order to guarantee precise and trustworthy measurements during concrete work, moisture meters must be calibrated and verified. When the device is calibrated correctly, it maintains consistency across various projects and conditions by aligning with known moisture levels. This is a crucial step because even small errors can cause serious problems with the quality and functionality of the concrete.

To ensure that the moisture meter stays accurate over time, verification entails routinely comparing it to accepted references. Through this procedure, any drifts or deviations in the meter’s performance can be found and quickly adjusted, or the meter can be recalibrated. Maintaining the integrity of concrete structures depends on routine verification to make sure the measurements are reliable.

In concrete projects, both calibration and verification help to improve decision-making and produce higher-quality results. Professionals can prevent expensive mistakes and guarantee that the concrete satisfies the necessary standards by devoting the necessary time and effort to these procedures. In the end, the project and its stakeholders gain from more dependable and long-lasting concrete constructions made possible by consistent and accurate moisture measurements.

When determining the moisture content of concrete, moisture meters must be calibrated and verified in order to guarantee accurate readings. In order to verify the device’s precision, it must first be adjusted to match a recognized standard. The quality and longevity of concrete structures can be impacted by inaccurate moisture assessments, which can be avoided with proper calibration. In addition to improving the moisture meters’ dependability, routine calibration and verification also advance better building techniques and strengthen structural integrity.

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