安装在风道系统中，工作原理是极易熔合金的温度控制利用重力作用和执行机构的作用关闭或开启阀门，在一定时间内能满足耐火稳定性和耐火完整性要求，起排烟或防火作用。

Installed in the duct system, the working principle is easily the fusiontemperature control of the gold, the use of gravity and the implementingagencies to close or open the valve, within a certain time to meet the fire-resistant stability and fire integrity requirements, from the exhaust or fire.