Butterfly valve is frequently used in the water supply net workbutterfly valve common failings include hard to be switched, corrosive, low seal performance, can not cope with emergencies like pipeline blowing off, as a result, it have to reinstall the valve for these situations. So butterfly valve selection should pay attation to the following aspects:
Select low torque structure and materials.
1) Shaft materialsIt includes the upper and lower shaft in the valve body and gear shaft, hob in the gear box. ideal shaft material is martensitic stainless steel2Cr13 underwent tempering and quenching
, have certain degree of hardness, intensity, rigidity, corrosion resistance, difficult to bend or deform.
2) In case of shaft corroding, it could select low friction coefficient self-lubricated bearings, multi sealing rings or change materials.
3) The structure design of Shaft should be reasonable. Some products select pins to connect both upper and lower shaft with disc, in this case, the distance of supporting poing of shaft and disc is far, the disc is easy to deform and displace. When pressure in forward direction, hard to open due to large specific pressure at sealing surface, in reverse, will leak. The new design butterfly valve with no pin connection, the lower shaft fixed with body, the distance between shaft and disc largely shortened, and specific pressre at seal surface only change a little. So the valve will be labor saving.