Product description

The backflow preventer uses the pressure of the medium to decompress due to mechanical resistance and the loss of the overflow head when the medium flows through the water inlet check valve, so that the inlet pressure is higher than the pressure of the drain valve cavity. The pressure on the upper part of the diaphragm of the drain valve is the inlet pressure, and the pressure on the upper part of the diaphragm is greater than the resistance of the drain valve cavity and the spring, the drain valve remains closed, and the medium flows normally. When the pressure difference between the inlet pressure and the pressure relief valve cavity is less than 0.02MPa, the medium is in a critical state of reverse flow. At this time, the upper pressure of the diaphragm is less than the pressure of the relief valve cavity and the resistance of the spring, and the relief valve automatically opens to discharge the reverse flow medium out of the pipe. At the same time, a large amount of air enters the valve body to form an air partition to prevent the medium from flowing back.

When the water pressure of the pipe network after the valve rises above the water pressure at the forward water end of the valve, if the second one-way check valve is well sealed, the water body will not flow back. At this time, the drain valve is closed and no water is discharged. When the second one-way check When the valve seal fails to cause leakage, the drain valve opens to drain and release the pressure.

Main external connection size