Non return valve

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As the fluid passes from the right opening into the valve body, it raises the pressure of the valve to its highest point for a limited distance. The fluid then exits between the valve's hairs on the left side of the valve body. If the fluid returns from the left side, it presses against the valve and closes it. This prevents any return of the fluid and is used in water networks, boilers, and similar systems to prevent loss or leakage of these fluids.