When it comes to a hygrometer, many people immediately remember devices that measure air humidity. This is really one of the most common types of hygrometers, which, according to experts, it is advisable to have in every apartment in order to control the humidity level. We briefly mentioned such a moisture meter when we talked about a humidifier.
Humidity meter often comes with a conventional thermometer and barometer. It is actually convenient – you can control the entire microclimate of the room, all its most important indicators. Such devices for the home are inexpensive – we managed to find a stylish electronic model of a thermometer-hygrometer for only 550 rubles. There are simpler and cheaper options.
Hygrometers for the home are considered not very accurate, they are usually able to work in conditions of humidity from 20% to 80%. However, at home, extreme accuracy is usually not needed..
Now let’s consider other options, because moisture meters are divided by type of application into meters for soil moisture, oil products, wood, and so on. We, as a construction site, will be primarily interested in a moisture meter for wood, because for sawn timber, moisture is a very important indicator of quality.
Who needs a wood hygrometer? Imagine that you are building a house, frame, from a bar, logs … Even in the case of a stone house, wooden beams are necessary for the construction of the roof. Therefore, you will definitely need a lot of building materials made of wood. The supplier will assure that all wood is perfectly dried and of enviable quality. If you act according to the principle of “Trust but verify”, you need a moisture meter to make sure that the supplier is right, the wood is well dried.
According to the principle of determining the moisture content of wood, hygrometers can be divided into needle and non-contact ones. Although it is impossible to call the device completely contactless – the moisture meter will still have to be applied to the material, it has special rounded contacts, but not immersed inside. Thus, the so-called non-contact hygrometer will not damage the material. According to the measurement method, moisture meters are divided into conductometric and dielectric:
- The first method is used with moisture meters with games. A conductivity meter measures the electrical resistance between probes immersed in the material, and then, based on this indicator, gives the percentage of moisture. The electrical resistance depends on the moisture content of the material, so the measurement is fairly accurate. The disadvantage of this method is that the needle sensors must be in good contact with the wood in order for the indicator to be accurate. In addition, if the tree is very expensive, it is undesirable to pierce it even with thin needles to a shallow depth..
- The dielcometric method of moisture measurement is based on scanning wood with high frequency currents. The scanning depth reaches 30 mm. Dielectric constant also depends on humidity. The device does not damage the material, as the sensors are simply applied to the surface. The measurement accuracy will be affected by the tightness of the sensors to the wood, you should press them thoroughly. In addition, if the surface of the tree is wet, for example, it has been exposed to rain during transportation, it will not be possible to measure the moisture content inside the material – the readings of the sensors applied to the wet place will simply go off scale.
Such indicators as the resolution of the moisture meter, that is, the measurement step, as well as the error are very important. For household devices for measuring air humidity, the normal error is plus or minus 2%. For wood hygrometers, the error can also be from 0.8% to 2%.
There are universal moisture meters that are suitable not only for wood, but also for concrete and screeds. In this case, contactless is, of course, preferable, because piercing hard concrete with needles-sensors is not an easy task.
The cost of hygrometers for wood, concrete and other materials can be very different. You can find models for both 1,500 and 15,000 rubles. Professionals who constantly work with lumber, of course, need a more accurate, modern, with additional functions and, accordingly, an expensive device. For home use and quality control of purchased boards, we think you can find a simpler model.