Stainless steel pneumatic valve leakage problem you know?

Still worry about stainless steel pneumatic valve leakage problem, then you have to have a look at this article.




seal is to prevent leak, the stainless steel pneumatic valve sealing principle is also from the world of prevent leakage. Cause leakage there are two main factors, one is the main factors influencing the sealing performance, namely gap exists between the sealing pair, the other is seal pressure difference exists between the both sides of the deputy. Stainless steel pneumatic valve sealing principle is also from liquid sealing, gas sealing, the sealing principle of leak path and stainless steel pneumatic valve seal and so on four aspects to analyze.
1, liquid sealing
the sealing is through the liquid viscosity and surface tension. When the pneumatic valve leakage of stainless steel capillary filled with gas, reject the liquid surface tension, or introducing fluid in capillary. Thus formed the tangent Angle. When the tangent Angle is less than 90 °, the liquid will be injected into capillary, it will leak. The leaking reason lies in the different nature of the medium. Experimenting on different media, under the same conditions, would get different results. Can use the air or water, kerosene, etc. The tangent Angle is greater than 90 °, and also will leak. With oil or wax film on metal surface. Once the film on the surface of the dissolved out, the characteristics of the metal surface is changed, the exclusion of the original liquid, will invade the wet surface, the leaking. According to the above situation, based on poisson's equation, can reduce capillary diameter under the condition of large and medium viscosity, to achieve the goal of prevent leakage or reduce leakage.

2, gas sealing
according to poisson's equation, the gas tightness is associated with gas molecules and the viscosity of the gas. Leakage is inversely proportional to the length of the capillary and the viscosity of the gas, proportional to the diameter of the capillary and the driving force. When the diameter of the capillary tube and the gas molecules at the same time, the average degree of freedom of phase gas molecules would have to free the thermal motion of flow into the capillary. Therefore, when we do stainless steel pneumatic valve seal test, medium must use water to have the effect of sealing, with air or gas will not be able to play the role of sealing. Even if our way through the plastic deformation, the capillary diameter to below gas molecules, and still can not stop the flow of gas. The reason is that gas diffusion can still through the metal wall. So when we do gas test, must test is more strict than those of liquids.




3, sealing principle of leak path

stainless steel pneumatic valve seal by not scattered on the waveform flatness and the distance between the peaks of waviness roughness of two parts. In our country, most of the elastic resilience of metallic materials are lower case, if you want to reach the state of the seal you need regarding the compression strength of the metal material is higher requirements, namely material than its elastic compression force. Therefore, when making stainless steel pneumatic valve design, sealing pair combined with a certain hardness difference to match, in under the action of stress, can produce a certain degree of plastic deformation of the sealing effect. If the sealing surface is metal material, surface smooth convex point will be the emergence of early in just at the beginning