HJA-1.0Backflow preventerIt is a method to prevent the pressure of non potable water pipes in the system from being temporarily higher than that of potable water pipes when the system malfunctions due to cross connection of water supply pipelines, and to prevent sewage from flowing back into the drinking water output pipeline system.

The so-called cross connection refers to the branch pipes connected from the domestic drinking water pipeline for the purpose of supplying non domestic drinking water. Common non domestic drinking water branch pipes include fire pipes, heat exchangers, boiler water pipes, production water pipes, sprinkler pipes, etc.

Material List of Backflow Preventer Parts number Part name Material Science 1 valve body cast iron 2 Valve cover cast iron 3 Spring stainless steel 4 diaphragm Nylon rubber 5 One way valve Bronze, stainless steel 6 axis stainless steel 7 Drain valve bronze 8 Middle cabin 9 One way valve Bronze, stainless steel

External dimensions of backflow preventer

Working principle of backflow preventer

When the water supply pressure is normal, the water flow is easy to flow from the two one-way valves to the outlet. Due to the local resistance of the one-way valves, the pressure in the middle compartment of the valve is slightly lower than the pressure, and the pressure in the upper part of the diaphragm is the pressure. Therefore, the pressure in the upper part of the diaphragm is greater than the water pressure and spring pressure in the lower part of the diaphragm. Therefore, the drain valve remains closed, and the water in the pipeline flows normally.

When all valves on the pipeline behind the backflow preventer are closed, the water flow stops. When the pressure remains constant, the pressure in the middle compartment is still relatively low, and the drain valve is still in the closed state; When the pressure drops to at least 0.014 MPa higher than the pressure in the middle compartment, the drain valve automatically opens to discharge the water in the middle compartment out of the system; When the pressure drops to about 0.02 MPa, the drain valve will open, allowing air to enter the intermediate compartment, forming an air gap twice the diameter.

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