--- The rapid change of drum water level would cause the steam pressure, temperature fluctuation. In the event of overflow or other water accident, the boiler would be forced to be shutdown. Therefore, water should be supplied continuously and smoothly so that the drum water level would be kept to be normal.
--- Normal drum water level line is 50mm lower than the drum central line. Normal water level fluctuation should be kept to be within 75mm. If the drum water level reaches to -100mm or +100mm, DSC sound and light alarming would be caused. When the drum water level reaches to -200mm or 250mm, MFT act would be.
--- When the boiler operates with the low load, the drum water level should be slightly higher than the normal water level so as to avoid the low water level caused by the increasing load. Conversely, it the boiler operates with the high load, the drum water level should be slightly lower than the normal water level so as to avoid the high water level caused by the decreasing of load. But the movement range should not exceed the allowable value.