The basic structure of the butterfly valve

1.Butterfly Valve body: it is a part of the water passage through which the water flows, supports the weight of the valve, bears the operating force and torque, and transmits the water pressure.

2).Butterfly Valve: it is used to cut off the water flow when it is closed. It is required to have sufficient strength. When it is opened, it has small hydraulic loss in the water flow center and good hydraulic characteristics.

3. Butterfly valve's Shaft and bearing: support the weight of the valve.

4. Spindle locking: the valve of butterfly valve needs spindle locking when it is fully closed or fully open.

5. Bypass valve and bypass pipe: when the main valve is opened, reduce the torque and eliminate the vibration under moving water.

6. Air valve: replenish air behind the butterfly valve when closed to prevent damage to the steel pipe due to vacuum. Exhaust when filling water behind the front valve when opened. The valve has a hollow pontoon suspended under the guide piston, which is on the water surface in the volute or pipe. In addition, the vent hole is communicated with the atmosphere to supplement air or exhaust the volute and pipeline. When the pipeline and volute are filled with water, the pontoon floats up to the limit position, and the volute and pipeline are isolated from the atmosphere to prevent water overflow.

7. Expansion joint: it is convenient for installation and maintenance. When the temperature changes, the steel pipe has room for expansion.

8. Sealing device: prevent water leakage between living body and valve. The rubber shroud is installed on the valve body or valve. When the valve is closed, compressed air rushes into the shroud, and the shroud expands to seal the circumferential gap. Before opening the valve, exhaust the air and retract the shroud before opening the valve. The compressed air pressure in the shroud shall be greater than the maximum water head (excluding the water hammer pressure rise value) (2-4) * 10 ^ 5pa. When not subject to air pressure or water pressure, the gap between the shroud and the valve shall be 0.5-1mm.