In part 3 of pneumatic valve leakage

there are two main types of pneumatic valve leakage part, one is the internal leakage; The second is leakage. When the medium temperature drop to make the material produces phase change caused by the volume change, make originally high sealing surface grinding precision warping deformations caused by poor sealing at low temperature. We have DN pneumatic valves for low temperature test, medium of liquid nitrogen ( - ℃) Butterfly plate material for CrNiTi ( Not treated with low temperature) Found that the sealing surface buckling deformation. Mm, this is the main reason for the cause of leakage. Newly developed the pneumatic butterfly valve sealing instead of cone sealing by the plane. Pneumatic valve leakage within the main reason is that seal caused by deformation produced in low temperature condition. When the medium temperature drop to make the material produces phase change caused by the volume change, make originally high sealing surface grinding precision warping deformations caused by poor sealing at low temperature. We have DN pneumatic valves for low temperature test, medium of liquid nitrogen ( - ℃) Butterfly plate material for CrNiTi ( Not treated with low temperature) Found that the sealing surface buckling deformation. Mm, this is the main reason for the cause of leakage. Newly developed the pneumatic butterfly valve sealing instead of cone sealing by the plane. Pneumatic valve seat is an oblique cone ellipse seal face, perfectly on the butterfly plate and a round of elastic sealing ring seal. Sealing ring can be radial floating in the butterfly plate groove. When the pneumatic valve is closed, the elastic sealing ring and short axis of elliptic sealing surface contact first, as the rotation of the pneumatic valve stem seal ring to push, forcing the elastic ring and long axis of the oblique cone surface contact again, eventually led to the elastic sealing ring and elliptic sealing surface contact. Its sealing is relying on the elastic deformation and reach. So when the pneumatic valve or butterfly plate deformation in low temperature, will be absorbed by the elastic sealing ring to compensation, won't produce leakage and jammed. When the pneumatic valves open the elastic deformation disappear immediately, basic no relative friction in the process of opening and closing, so the long service life. Pneumatic valve leakage reasons: one is the pneumatic valve and pipe flange connection with the payment, due to the connection pad material, connecting bolts, and fitting materials under low temperature shrinkage of sync between relaxation and lead to leakage. So we put the pneumatic valve and pipeline connection from flange connection to the welding structure, to avoid the leakage in low temperature. Secondly, pneumatic valve stem and packing leakage. Generally most of the pneumatic valve packing using F, because it from sliding performance is good, small friction coefficient, F = friction coefficient of steel. ～。 ） , but also has the unique chemical stability, so widely used. But also have shortcomings, F is a cold flow tendency; Second, linear expansion coefficient is big, produce in the low temperature cold cause leakage, in a large number of ice, pneumatic valve stem failure to make the pneumatic valve is opened. Developed by low temperature adjustment for this pneumatic valve adopts the seal structure of the advantage of the characteristics of F large expansion coefficient, through to stay on the sidelines of achieve the goal of normal temperature, low temperature can be sealed. http://www pneumatic pneumatic valve manufacturer. /。