900X Emergency Shut-off Valve

The 900X Emergency Shut-off Valve is used in parallel water supply systems for domestic and firefighting purposes. Under normal conditions, it supplies domestic water. When a fire occurs and firefighting water is required, the 900X Emergency Shut-off Valve automatically shuts off the domestic water supply to ensure sufficient firefighting water. When firefighting water demand ceases and pressure decreases, the 900X Emergency Shut-off Valve automatically restores the domestic water supply. This valve eliminates the need for a separate dedicated firefighting water supply network, significantly reducing construction costs and daily water consumption. This valve features responsive control, reliable safety, simple commissioning, and a long service life.

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900X Emergency Shut-off Valve Working Principle

When the inlet pressure of the main valve falls below the pressure set by the pilot valve, the pilot valve remains open. The pressure within the main valve's upper chamber equals the outlet pressure, creating a pressure differential between inlet and outlet. Water flows through the valve orifice and exits via the outlet. When the fire pump starts or the pressure from the variable frequency pump increases, exceeding the pilot valve's set pressure, the pressure in the control line connecting the main valve inlet to the pilot valve rises. This increases the pressure on the spring, forcing it downward and pushing the spool down to close the pilot valve. At this point, the pressure at the main valve inlet continuously supplements the pressure in the upper chamber of the main valve cover through the throttle valve. Since the downward pressure on the valve disc exceeds the upward thrust, the main valve closes. It is important to note that the valve remains open when the inlet pressure is below the set pressure, and closes when the inlet pressure exceeds the set pressure.