Mirab co. Fixed Cone Free Discharged Valves are capable of keeping the flow in a constant and steady condition. In addition, it can increase the volume of flow in an emergency situation e.g. flood water or etc. (The reason for increasing flow, is to prevent any damage to the side walls of the dam.) The structure of Fixed Cone Free Discharged Valves is made firmly and rigidly to eliminate any cavitation and vibration and prevent harm to other structures. In high-speed flow, water takes some big solid parts into the valve (such as stones, wooden parts, etc) the structure of the valve is so that these parts cannot harm the body of the valve and they can pass through the valve and will not make any difficulty for opening and closing.