The flame retardant quality of wooden fire doors is related to the fire resistance limit of wooden fire doors. Therefore, many fire door manufacturers set up this process as a special process control point in the production process, but due to the lack of mature process regulations in the flame retardant process, various manufacturers The flame retardant process is different, the flame retardant process is not very reasonable, and the quality of the flame retardant cannot be guaranteed. In serious cases, the fire resistance of the fire door is reduced, causing potential hidden dangers to the lives and property of the people.

  Common flame retardant methods of wood are: spraying method, soaking method, cooking method, vacuum method, vacuum pressure method, etc. The spraying method and the soaking method are generally applied to the wood surface that is no longer planed, and the flame retardant treatment of the thin plate with a thickness of less than 10mm is not suitable for the production of wooden fire doors. Although the vacuum method and the vacuum pressure method have good flame retardancy, they have not been used in fire door production enterprises in our province because of their expensive equipment. At present, most of the fire door enterprises in our province adopt the cooking method for flame retardant treatment. The author believes that the following points should be noted when using the cooking method for flame retardant treatment:

  1. The wood to be flame-retardant is also wet or dry

  The moisture content of the wood to be flame-retarded is an important factor that affects the flame-retardant quality of wood. Because the dry wood enters the flame retardant pool, it is easy to absorb the flame retardant liquid, and the amount of the flame retardant liquid absorbed by the wood directly affects the flame retardant quality of the wood. Its absorption is directly proportional to the oxygen index and the flame retardant depth of the flame retardant wood. . The more wood absorbs the flame retardant liquid, the better the flame retardant performance of the wood, the higher the oxygen index, and the deeper the flame retardant depth. However, many companies believe that anyway, the wood must be soaked by the flame retardant liquid when it is flame retarded, so the high and low moisture content of the wood does not matter much. The fire-retardant wood is generally not dried, and some companies will even The wet sawn timber just sawed is flame-retardant. It is unknown whether the moisture content of wood will affect the flame retardant quality, and the flame retardant quality of flame retardant wood is unstable. According to the test, under the same flame retardant conditions, wood with a moisture content of less than 15% can increase the oxygen index by more than 5 than wood with a moisture content of more than 40%, and the flame retardant depth can be increased by more than 3mm.

  2. Fire retardant first, then water, then wood

  In the flame retardant process, most manufacturers adopt the order of installing wood → adding flame retardant → adding water → starting flame retardant. Generally speaking, when wood starts to absorb the most water, the process often causes the wood to start to absorb low-concentration flame retardant liquids. In this way, in the process of wood flame retardant, a low concentration of flame retardant liquid absorbed by wood is needed. The process of excessive concentration to normal concentration directly affects the dry salt absorption and absorption rate of wood, which in turn affects the flame retardant effect. And the order of adding flame retardant → adding water → installing wood → starting flame retardant, the wood absorbs the standard concentration of flame retardant liquid at the beginning, thus avoiding the process of excessive absorption of flame retardant liquid from low concentration to normal concentration , Which in turn improves the flame retardant quality. If the company has the conditions, the flame retardant can be formulated into a flame retardant liquid with a specified concentration before being added to the flame retardant pool. The flame retardant quality is good.

  3. Cover with flame retardant, reduce the evaporation rate of flame retardant liquid

  In our normal flame retardant process, the process of heating and cooking is generally carried out open, which results in the flame retardant liquid evaporating too fast. Often a flame retardant process needs to continuously add water to the flame retardant pool. The flame retardant liquid absorbed by the wood is dissolved from a high concentration state to a low concentration, then absorbed to a high concentration, and then dissolved to a low concentration, thereby reducing the dry salt amount of the flame retardant liquid absorbed by the wood. However, if capped flame retardant is adopted, firstly, the addition of raw water during the flame retardant process can be avoided, secondly, the concentration of the flame retardant liquid in the flame retardant pool will not be suddenly increased, and thirdly, energy can be saved. If you still cannot avoid adding water halfway, you should also add the prepared flame retardant to ensure a constant concentration of flame retardant in the flame retardant tank.

  4. Discharging at room temperature

  Many fire door manufacturers often use time as the flame retardant standard in the flame retardant process of wood. According to the requirements of the operating regulations, the required time is reached, and the material is discharged as soon as the time is up. This makes the workers too hot during the operation, which is not conducive to labor protection. What is important is that during the process of the wood being cooled by heat, the cells inside the wood generate a certain negative pressure due to thermal expansion and contraction. Under the effect of negative pressure, the flame retardant liquid is further absorbed, thereby improving the quality of the flame retardant treatment.