Phenomenon: 

1. The hearth negative pressure increases suddenly, the primary and secondary air pressure is reduced; the flame is not shown in the industrial television and local fire hole, the flame monitoring device alarms. 

2. The steam temperature and steam pressure drop, the drum water level drops first then rises. As for the DC boiler unit, the  machinery protective  device of steam turbine acts to stop the unit, and the team pressure will rise for short time. 

3. After the protective device for fire going out acts, all the coal pulverizing systems trip, the quick-break valve for oil feeding for oil gun is closed and locked. 

Precautions After the fire goes out in the boiler, it is forbidden to supply pulverized coal, oil and gas to the boiler, all the fuel shall be shut off. In case the boiler fire extinguishing protective device can't correctly act, it is timely required to manually cut off the supply of all fuel to take measures against misoperation. It is required to take strict precautions against accident "Firing a Gun" of fire going out.