1. When the boiler steam pressure and water supply pressure are normal, but the steam drum water level is lower than the normal water level, the following measures shall be taken: 

(1) Flush and valid whether the local water level gauge instructions is correct or not. 

(2) Immediately change the automatic water- supplying to manual water-supplying in order to increase the water supply amount. 

(3) If the adjusting to water supply valve cannot increase the water supply, the bypass shall be opened for water supply. 

2. If the water supply pressure is low, it is required to inform the person on-duty for the steam turbine to increase the pressure of water supply.  If the water supply pressure cannot be recovered belatedly and the water level of steam drum is lowered, after asking instruction from the superior for approval, the person on-duty can reduce the boiler evaporation capacity or reduce the boiler pressure in order to maintain water level. After the water supply pressure recovers to normal water level, the parameters can be increased to the rated value. When the water supply flow is less than the steam flow, it is forbidden to take the method of increasing the evaporation capacity to increase the water level of water drum. 

3. After the above processing,  the water level continues decreasing to - 100 mm, at this moment, inform the shift chief operator to close all the blowdown valves and water draining valves besides strengthening water feeding continuously. If necessity, the boiler evaporation capacity can be reduced appropriately. 

4. If water levels continue decreasing, the water level disappears in the steam drum water level gauge, it is required to stop the boiler immediately, close the main steam valve and continue to strengthen water-feeding. 

5. Due to the operator's negligence, the water level disappears in water level gauge and is not found in time, it is required to take method of "closing the valves at steam side and individually open the valves at water side" to judge the water level. If it is judged that the water is in severe shortages, the boiler operation shall be immediately stopped. Close all the water supply valves and it is forbidden to supply water to the boiler, and the causes of water shortage of boiler shall be found out. 

6. If the boiler is shut down due to severe water shortages, after shut-down of the boiler, the bottom materials and circulating ash shall be emptied immediately and the fan damper and manhole gate shall be closed for natural cooling.