1. The design of valve components shall be able to facilitate maintenance, installation and disassembly, and meet the requirements of operation conditions. The valve body shall be able to be transported and lifted as a whole.

2 for valves with specific flow direction requirements, the flow direction shall be clearly and permanently marked on the valve.

3 to minimize cavitation, eddy current and pressure drop, the disc of butterfly valve is fixed on the valve rod.

4 valve body: the valve body is an integral casting. The overall dimension of the valve body shall meet the requirements of relevant standards.

5 valve plate: the valve plate is cast into a streamlined simple piece, minimizing the resistance of the valve to the fluid.

6 valve shaft: the valve shaft is also made into a whole, with a standard key at one end.

7 seal

a. Butterfly valves meet the sealing requirements under the following pressure difference: 0.6MPa at the inlet and outlet sides.

b. Butterfly plate and valve seat seal

The sealing of butterfly valve adopts metal hard sealing. The bidder shall provide the supplied valve according to the sealing design of three eccentric surfaces.

c. Stem seal

The stem seal adopts the anti sediment type shaft seal device to prevent the external substances such as sand in the water flow from entering the bearing.

d. All valves shall be able to replace the packing without removing the actuator, and the valve stem shall not be extended to meet the requirements.

8 bearing

The valve rod bearing shall be placed in the bearing seat of the valve body. The bearing shall be made of self-lubricating material which has no adverse effect on water and rubber, with small friction coefficient and no need of maintenance in use. Reliable operation. When the bearing bears the maximum radial force of the valve rod, it can ensure the normal rotation of the valve rod without scratches or harmful deformation. The axial positioning of the valve rod adopts the rolling bearing positioning, which effectively prevents the axial movement of the butterfly plate, and the service life of the bearing is required to be more than 30 years.

9 all valves shall be equipped with adjustable travel stops to prevent the valve from overstroking in the open / close position.

10 butterfly valve seats shall be mechanically fixed. No special tools or procedures are required to replace the seats.

11 the butterfly valve shall be equipped with two-way thrust bearing which can be adjusted on site to limit the axial movement of the valve stem and maintain the calibration between the valve disc and the valve seat. The bearing shall be adjusted by the manufacturer.