介绍挤塑保温板b1级和b2级耐火等级区别的方法：
This paper introduces the difference between B1 and B2 grades of extruded insulation board
b1级为离火窒息级，即离开火源后自动熄灭，或10秒内熄灭。
Class B1 is the asphyxiation level, that is, it will automatically extinguish after leaving the fire source, or it will extinguish within 10 seconds.
b2级为缓慢燃烧级，即点着以后火势不会变大，且滴落物不会引燃滤纸;
B2 is a slow burning stage, that is, the fire will not increase after ignition, and the drop will not ignite the filter paper;
肉眼判断的话，B1级挤塑板离火三秒钟自熄，点着以后离开火源，三秒内自熄的就属于B1级挤塑板，B2级挤塑板缓慢燃烧，这个就是比较模糊的概念了，只有与普通板对比才能看出效果，明显燃烧速度慢的就属于B2级挤塑板。
If judged by the naked eye, the Class B1 Extrusion board will be extinguished within three seconds from the fire, and leave the fire source after ignition. The Class B1 Extrusion board will be extinguished within three seconds, and the class B2 Extrusion board will burn slowly. This is a relatively vague concept. Only when compared with the ordinary board can we see the effect. The class B2 Extrusion board is obviously slow in burning.
所以这个肉眼界定也得有对比才能看出区别来的
So the visual definition has to be compared to see the difference