High temperature treatment can improve the dimensional stability of various wood-based panels. It is not a new concept and has been used in hardboard since the 1950s. High temperature is also applied in solid wood. Although the applied technology is different, the basic principle is the same, that is, the wood is heated to a high temperature in an oxygen-free medium, and the temperature used depends on the degree of wood modification. , but usually exceeds 200 ° C, typically 230 ° C to 240 ° C. At this temperature it is easy to catch fire, so reducing the oxygen content is the most important safety requirement. However, the low-oxygen environment also causes a chemical change in the modification reaction of the high molecular polymer in the wood.
Although the wood high-temperature treatment process does not add chemicals, it can change the chemical properties of the wood. In other words, some of the high molecular weight polymers and molecules in the wood have changed due to the chemical mechanism. The result is that the heat treated wood is chemically different from the untreated wood.
The heat treatment of wood-based panel production may have the following advantages: increase the dimensional stability of the board, enhance the antibacterial ability of the board, and reduce the density.
The benefit of these benefits is related to the less moisture absorbed by the heat treated wood. For example, heat treated wood has a fiber saturation point of about 15%, while untreated wood is about 30%, only half of the latter, so its swelling is only half that of the latter. Fungi and bacteria need water when they invade wood. If the moisture content of wood is less than 18%, it can usually avoid bacterial erosion. Therefore, if the heat-treated wood is not in direct contact with the ground, it can effectively prevent fungal and insect damage.
The density of the heat-treated wood is low, in part because of its low water content and the loss of various organic matter due to evaporation or lowering during high-temperature treatment. This will be an advantage in the production of wood-based panels: under the premise of the same technical performance, the lower density of wood-based panels is better.
Of course, all processes have an insufficiency. Heat treatment will make the wood color darker, its mechanical properties will be reduced, the glue performance will be poor, especially the toughness will be reduced, and its cost will increase. For wood fibers and shavings that must be dried, proper heat treatment can be considered. Perhaps existing production lines can use this technology to improve the performance of wood-based panels without significantly increasing costs.
Globe Valves and angle valves are designed for throttling or regulating flow in commercial and industrial applications. Bronze, cast iron, or cast ductile iron materials. Threaded, flanged, or solder end connections.
Angle valves for use in commercial and industrial applications. Typical services include hot and cold water, HVAC, steam, compressed air, gas and other general utility services.
Vacuum angle valve is used for turn on or shut off the airflow in the vacuum pipeline, the applicable media is air and non-corrosive gases.
It has two structures, one is angle type and another is a 3-way type within an ISO-KF or ISO-F various flange end pre-pump port.
a) Small diameter (≤DN50) valve body are precision investment casting.
b) Large diameter (> DN50) valve body are molding shaped seamless steel or steel plate.
c) Bellows sealed structure can withstand 150ºCtemperature, metal sealed structure can withstand 450ºCtemperature.
d) Can install on any position to control the airflow in the vacuum pipeline, as an on-off valve purpose
Angle Valves, Angle Globe Valves, Brass Angle Valve, Zinc Angle Valve
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