Conducting a test, setting up and calibrating a hygrometer

Knowing the amount of moisture in your surroundings is important for a number of reasons, such as keeping your home comfortable or protecting the integrity of concrete structures. This is where an accurate humidity gauge, such as a hygrometer, comes in useful.

Make sure your hygrometer is calibrated and properly set up before depending on it for accurate readings. If not adjusted correctly, even high-quality hygrometers can provide readings that are off. Getting the most accurate data can be achieved through a simple process of testing and calibration.

We’ll show you how to perform a quick test to determine the accuracy of your hygrometer in this article. To ensure that you can rely on the readings the device provides, we’ll also go over how to set it up and calibrate it. These instructions will assist you in maintaining the best possible condition for your hygrometer, whether it is being used for comfort, maintenance, or construction.

What is it?

The process of establishing a link between the value indicators (obtained during a particular measurement) and the corresponding value of the value obtained using a standard is known as hygrometer calibration. Inaccuracies in measuring and reading air humidity can be found and removed with the use of calibration.

A hygrometer’s calibration enables you to identify the dimensions of the device’s errors, remove errors, and fine-tune its operation for maximum accuracy with an error of 0-1%.

Devices that are mechanical (having an arrow) or electronic require calibration in order to enable accurate adjustment to readings. The best way to guarantee measurement accuracy is to compare and trace (by indicators) with a functional, certified device.

The hygrometer has a unique material that absorbs moisture instantly and a mechanism that tracks how quickly the material absorbs moisture, providing an indication of the air’s humidity.

Accurate humidity readings are critical for many concrete and construction applications, so it is important to test, set up, and calibrate a hygrometer. The ideal conditions for material handling and curing processes can be maintained with the aid of a properly calibrated hygrometer. This tutorial will assist you in making well-informed decisions for your projects by taking you through easy steps to test, calibrate, and set up your device to ensure dependable performance.

How to set up correctly at home?

There are a few ways you can check the hygrometer at home on your own. The first is to identify any deviations in the readings’ accuracy, and then you can make the necessary adjustments.

Comparison with a precision instrument

You can compare a hygrometer’s "work" with an accurate hygrometer (if you have one) if the owner finds glaring errors in the readings. For this:

• both devices are left side by side for 10-15 hours in a specific place/room;
• after the deadline, the readings are checked;
• if the reading on the correct device is, for example, 65%, and on the one being tested 50%, then the latter is adjusted to 65%.

Use a special key or screwdriver to help adjust the adjusting screw to the desired position in order to accomplish this. If there are minimal differences between the readings, you can make the test a little more difficult. The devices are tested in a dry room first, and then their readings are compared when they are placed in areas with noticeable humidity (such as a sauna or bathroom).

It is best to buy a hygrometer from reputable manufacturers in specialized stores to avoid purchasing easily recognizable fakes. People place the device close to their mouths and inhale deeply into it multiple times. You might be holding a "gift" from con artists that doesn’t even have an installed humidity sensor if the readings don’t change.

The hygrometer’s readings are compared to those of any advanced air humidifiers in the home that have an integrated (accurate) humidity sensor.

Testing with water

There are steps involved in calibrating the device with water:

• a towel or any material is immersed in a container with water (warm);
• excess moisture is lightly squeezed out;
• The device being tested is wrapped in a towel; it must be completely contained in the towel (without lyes);
• put it in a container with a sealed (hermetically sealed) lid, or in a plastic bag, tying it tightly – the device should lie strictly horizontally;
• after a few hours (2-4 hours) the hygrometer is released from its damp "captivity";
• look at the readings, which should be around 95-98%.

If the numbers differ, make the necessary adjustments and calibrate the device to the desired readings as soon as possible—ideally within a minute. In a mechanical hygrometer, the axis is fixed after the arrow is loosened and moved to the 95–98% mark.

The testing area should be warm, and drafts should be avoided by closing the windows.

Using salt for mechanical devices

Experts believe that testing a hygrometer with a saline solution yields the most accurate results; the humidity level should be no higher than 75%. The examination is conducted step-by-step:

1. Prepare a large container where you can put a hygrometer and a jar / glass with a saline solution.
2. Pour 3-4 tablespoons of regular table salt (or any other) into the jar, pour in a small amount of water to make a thick saline solution.
3. The jar is placed in a container.
4. The device to be tested is also installed there.
5. Everything is tightly closed with a lid, or covered with a thick film, tying the edges of the container with twine.
6. Leave for 4-8 hours. It is after this time that the humidity in the container reaches 75%, as experts believe, and no more.

The hygrometer readings are checked after the container is opened; if they differ, calibration is required. It needs to be done right now—within a minute—because the indicator is at 75%.

Freezer bag

Another method to verify the hygrometer’s accuracy is to use a freezer bag. For this:

• put 2-3 tablespoons of salt in a glass, fill with water until the consistency of thick porridge;
• a hygrometer is placed in a freezer bag and a glass with a saline solution is placed;
• the bag is hermetically sealed and left for two hours;
• after the time has elapsed, the bag is opened and the device readings are looked at;
• the data should correspond to a humidity of 75%.

In the event that the hygrometer displays additional data, it is quickly corrected (by moving the arrows and screws to the proper positions).

When installing (using one of the tests) inaccurate readings, it is best to take an electronic hygrometer with a warranty service period to a service center where the issue will be professionally and cost-free fixed. Since calibration is typically not included in these options, it is unlikely that you could calibrate an inexpensive hygrometer yourself.

But, if the product has no warranty, you can attempt to modify mid-range and premium models. Remove the screws or disconnect the parts to disassemble the device body; do not remove the front panel.

The humidity sensor has a very thin and sensitive coating that prevents you from touching or wiping it (for no reason).

The electronic hygrometer circuit is the same for all of them. She is made up of a board that has the following on it:

• drop-shaped microcircuit;
• beige capacitors;
• black resistors;
• cylindrical metal resonator;
• sensors – humidity (white square with a “labyrinth”) and temperature (black droplet).

It is possible to modify the device’s reading accuracy by swapping out the humidity sensor. Retail stores with specialized inventory sell it.

The surface of the humidity sensor should be covered with a thin layer of hygroscopic material, such as brake fluid, if the humidity is consistently (suspiciously) low at 10% to 20%. It would be appropriate to combine laundry soap, polyamide imide, and polyethylene glycol. If the hygrometer’s readings are consistently elevated, remove a small amount of the extreme side’s moisture-sensitive layer.

You can fix inaccurate readings by swapping out resistors R1, R2 for trimmer resistors. By soldering a trimmer resistor in series or parallel to the humidity sensor, you can further modify the device. Next, modify the resistance to alter the readings.

Possible errors and complications

Hygrometers come in a variety of varieties; some need to be calibrated, while others don’t (though they still need to be of excellent quality). As an illustration:

• models with natural hair or a metal spiral require calibration;
• a device with synthetic hair does not require calibration, or it is needed very rarely;
• digital models also do not need to be calibrated – their accuracy depends on the manufacturer, a well-known brand guarantees the quality of its products.

Experts advise calibrating equipment that needs to be checked twice a year. Accurate readings are ensured by doing this.

It should be kept in mind that an adjustment needs to be made within a minute of the device being calibrated and identifying incorrect readings. Should adjustments be made afterwards, the hygrometer will function with distortions once more.

While calibrating, additional mistakes could happen:

• when testing with water, the towel did not completely cover the device, the humidity shows 51% – the cycle should be repeated using a large (in size) towel;
• when calibrating (a precision instrument) with a salt solution, the result is 60% – perhaps the salt was taken less than normal, or the seal of the container was broken.

What happens if you don"t calibrate?

The hygrometer’s performance could decline because it is always responding to variations in humidity and temperature throughout the year. The accuracy of the sensitive device is significantly and strongly impacted by external environmental factors.

If you neglect the device’s scheduled, timely checks and settings, it will generate inaccurate, distorted data and eventually malfunction.

Useful video

About three methods for adjusting gadgets before a bath:

For accurate measurements of humidity, a hygrometer’s calibration must be precise. These devices’ accuracy is maintained through routine testing and calibration, which yields reliable and consistent readings essential for a range of applications, from industrial processes to weather monitoring.

Although using a hygrometer and setting it up might seem simple, it involves careful handling and close attention to detail. You can check the accuracy of your hygrometer and make any required adjustments by following the right procedures, which include using a reference standard like a salt test or a calibration kit.

Recall that frequent use and environmental factors can cause even high-quality hygrometers to drift over time. To ensure that your hygrometer continues to provide accurate data—which is necessary for making decisions based on humidity levels—regular calibration is recommended, ideally every few months.

Whether for industrial, scientific, or personal use, you can prolong the life of your hygrometer and ensure the accuracy of your humidity measurements by following these easy steps. It pays to take the time to set up and calibrate properly because accurate and reliable readings are guaranteed.

Video on the topic

How to set up a hygrometer for a bath

Three ways to calibrate a hygrometer in a bath

How to check a hygrometer for a bath?

Hygrometer. Calibration of a hygrometer. How to calibrate and check a hygrometer?