Wood: how and why to measure its moisture?

Wood - 04/05/2021
Did you know that wood moisture is one of its important physical properties? Here in this article you will learn how and why to measure wood moisture. This variable affects not only the quality of inputs in forest-based industries, but also the quality of its final products: sawn wood, panels, frames, floors, furniture, packaging and even fuel. In addition, moisture is correlated and influences other material properties such as bulk density, mechanical strength, resistance to biodegradable agents and others. Wood is a hygroscopic material: it easily absorbs and releases water content in search of balance with the relative humidity of the air. When the pieces are very moist, the water is more easily released. When they are drier, the drying phenomenon takes longer to happen. The visualization of the different scenarios of the movement and storage of water in a hygroscopic and heterogeneous material such as wood provokes the question: at what time and how to measure humidity? Instrumentation, automation and metrology provide the solutions for this important control to be carried out and the purpose of this text is to briefly describe, for each industrial stage, how this control happens. In the first stages of the forest-based industries, the wood is still in the form of logs, whose remuneration is commonly measured by mass (R $ / kg). In this case, the higher the humidity of the logs, the heavier are the commercialized loads and consequently more expensive. This is why humidity is important at this point. To measure the humidity in this step, the M65 Umilog equipment from Marrari Automação can be used. The person responsible for receiving the material in the yard drills a hole in some samples still on the truck, checks the humidity compliance using the sensor and, from there, calculations of correction of the cargo price can be performed according to the amount of water and even forecasting a stock of ligneous material in the yard, need to buy more raw material, etc.
Medidor de Umidade para Toras Marrari M65 Umilog
The industrial stage of wood drying is one of the most important and it is in which the moisture measurement stands out the most. Here, the moisture content can be used to guide and control the drying itself and it is he who defines which parts are ready to proceed to the processing stage and which parts must be discarded or sent to by-product lines, for example. The good drying of wood is essential to prevent attacks by biodegradable agents such as fungi and bacteria and to guarantee the stability of parts that will be transformed into floors, furniture or structural components in the future. Marrari Automação is a specialist in wood drying and provides, for this, different options of controllers and drying managers that are part of the MR500 family such as EcoPower, New Smart and New Easy. There are also manual ways to check the humidity of wooden piles inside or outside the greenhouse quickly and covering many samples – thousands of readings, in order to know widely the distribution of humidity in the piles – using, for example, the sword meter M55 / 56. The sword meter does not have this name for nothing: the sword shape allows the insertion of the humidity sensor in the center of the wood piles, which generally cannot be reached by the operator.
Wood Moisture Meter - M55-56 Sword
In the stages of processing and finalizing production; as in the sawmill or even checking port loads for export, the measurement can be carried out with very practical equipment: the M51 or M52 meters provide immediate results and are small portable instruments. Wood Moisture Meter - M51 Wood Moisture Meter - M52 It is inevitable to realize that the wood industry is following a joint path with technology, instrumentation and automation. Without solutions and innovations such as those mentioned above, ensuring the quality of wood becomes extremely difficult, generating wear, rework and waste. Marrari’s objective is the alignment between the continuous improvement of the quality of the wood and the supply of solutions that allow greater agility in the industrial processes. All details about the instruments referenced in this text can be found in the products tab of this website. To learn more about other industrial processes, check out the other blog articles too! Author: Elisa Pizzaia Goltz Industrial Wood Engineer (UFPR, 2014) Master in Forestry Engineering (UFPR, 2018) Quality / technical manager of the Umilab laboratory at Marrari Automação
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