Sealing is to prevent leakage, so the principle of valve sealing is also studied from leak prevention. There are two main factors that cause leakage. One is the most important factor affecting the sealing performance, that is, there is a gap between the sealing pairs, and the other is the pressure difference between the two sides of the sealing pair. The principle of valve sealing is also analyzed...

(1) Soft sealing material A. Nitrile rubber (NBR). Nitrile rubber has excellent oil resistance; heat resistance is superior to natural rubber and styrene-butadiene rubber; air tightness and water resistance are better. Nitrile rubber can be divided into butyronitrile-18, butyronitrile-26 and butyronitrile-40. Nitrile rubber is suitable for petroleum products with a temperature of -60 ° C ~ +120 ° ...

The factors affecting the sealing performance of the c are as below: A. sealing surface quality; b. sealing surface width; c. pressure difference; d. sealing surface material and its processing state; e. medium properties; f. surface hydrophilicity; g. the existence of sealing oil film ; h. the solid and structural characteristics of the closure. 1) Influence of sealing surface quality on valve se...

3. The influence of pressure difference before and after valve on sealing performance Theoretically, the pre- and post-valve pressure difference and leakage are proportional. However, the test proved that, under the same conditions, the increase in leakage is more than the increase in pressure difference. 4. The influence of sealing surface material and its treatment state on sealing performance T...

(6) Effect of surface hydrophilicity on sealing property The hydrophilicity of the surface affects the amount of leakage due to the characteristics of the capillary. When there is a thin film of oil on the sealing surface, it is necessary to increase the pressure of the water passing through the gap. Due to the good hydrophilicity of the metal surface, kerosene can easily penetrate the gap between...

As a component used to realize the on-off and flow control of pipeline system, butterfly valve has been widely used in many fields such as petroleum, chemical industry, metallurgy, hydropower and so on. There is an advanced butterfly valve: three eccentric metal hard seal butterfly valve. The valve body and the valve seat are connected components, the sealing surface of the valve seat is overlaid ...