100D constant water level valve is used for the automatic water supply system of the pool or water tower, when the liquid level reaches the set height, the valve transmits the signal to the pump through the relevant structure, the pump stops the water supply, when the liquid level is lower than the set position, the pump automatically starts the water supply, effectively prevents the pump from stopping the water hammer, to avoid the pipeline from generating too high pressure, the valve control is sensitive, the liquid level control accuracy is high, the water level is not disturbed by water pressure and closed tightly without leakage, reliable performance and long service life.