JM742X diaphragm bottom sludge discharge valve is composed of main valve, two position four same direction valve and valve disc. When the two position four-way reversing valve is in the one state position, the water enters into the middle chamber of the main valve, and the upper chamber opens to the atmosphere. Under the pressure of water, the diaphragm drives the valve disc to rise, the main valve opens, and the sediment and other pollutants at the bottom of the pool begin to be discharged; when the two position four-way reversing valve is in the second state position, the water in the middle chamber of the main valve is discharged to the pool, and the water is fed into the upper chamber, and the main valve is closed to stop the discharge of sediment. The valve is installed outside the bottom wall of various sedimentation tanks to remove sediment and dirt at the bottom of the tank. The opening and closing action is controlled by the reversing valve, which can react quickly and close accurately.