Non-asbestos sealing material
What is non-asbestos sealing material:
A series of non-asbestos seals made of organic fibers such as aramid and plant fibers, nitrile rubber and minerals through the process of calendering or copying.
Non-asbestos gasket:
Sealing products of various shapes made of non-asbestos sealing materials (using aramid fiber, high temperature resistant synthetic mineral fiber, oil resistant rubber and other materials), stamping and shearing by rolling method or various tools.
Internationally recognized asbestos is a carcinogen. In the 1970s, many countries proposed asbestos-free plans. After more than 20 years of hard work, the United States, Japan, and Australia have successfully developed various series of asbestos-free gasket materials. In 1990, the US Environmental Protection Agency EPA issued government regulations to prohibit Asbestos materials and their products are used. Nowadays, advanced countries in the world have promoted non-asbestos materials to various application fields, and banned asbestos materials.
Traditional asbestos materials have been used in China for a long time. After China's accession to the WTO, all walks of life in the country are facing foreign challenges. The automotive industry is at the forefront of industrial reforms. Volkswagen and GM of the United States have brought the concept of asbestos-free sealing of automobiles into China as the automobile giants. Shanghai Materials Research Institute started to produce non-asbestos gasket materials. With the rapid development of the domestic automobile industry and more foreign-funded automobile companies investing in factories in China, the asbestos-free car parts have been started; in the petrochemical and marine industries, the chemical corrosion of asbestos materials on steel bodies is often a major accident Hidden dangers; in the refrigeration industry, especially air conditioners and refrigerators are closely related to people's lives, asbestos will cause great harm to the human body and the environment.
ASBESTOS FREE GASKET or NON ASBESTOS GASKET generally mentioned in European and American countries refer to gaskets that do not contain asbestos. It should be said that the translation into Chinese can be said to be "asbestos-free gasket" or "non-asbestos gasket", but some companies in the Chinese market call gaskets containing a certain amount of asbestos (5-20%) as non-asbestos gaskets. The 100% asbestos-free gasket is called asbestos-free gasket.
As the asbestos-free gasket series not only has high strength, but also has good resilience, and at the same time has super strong anti-permeability, they are environmentally friendly sealing gaskets that replace asbestos gaskets in the field of automobiles and industrial machinery.
Performance of non-asbestos gasket:
1. Tensile properties
The gasket is mainly under pressure rather than tension. Therefore, the tensile performance of non-asbestos gaskets is not a very important factor in evaluating the quality of gaskets. Generally, as long as the tensile strength meets the requirement of greater than 7 MPa, the tensile strength of most non-asbestos gaskets is currently in the range of around 10 MPa.
Although the tensile properties of non-asbestos gaskets are not critical in assessing their quality, they are an important indicator in determining the stability and repeatability of gasket materials. The degree of damage.
2. Compression resilience
Compression resilience is to prevent surface and internal leakage, to prevent some fluid from leaking through the material itself or leaking between the sealing surfaces. Therefore, compression resilience is an important parameter of gasket performance, and its size directly affects the quality of gasket sealing. At room temperature, the compression rebound performance can be measured by compression test. Different test conditions have different values ​​of rebound rate and compression rate.
Generally speaking, the compression rate of non-asbestos gasket composites is higher than that of asbestos gaskets, and the rebound rate is lower than that of asbestos gaskets. Generally, CFS requires a compression rate of 7% to 17%, and a rebound rate of greater than 50%, which is basically the same as CAF.
3. Creep relaxation performance
Creep relaxation is related to many factors. It is an important indicator to reflect the deformation of the gasket, it is the embodiment of the instantaneous stress-strain relationship, and it is also the most important factor affecting the performance of the gasket.
The slower the creep loosening process, the better the sealing performance of the gasket. For asbestos-free gaskets, the creep relaxation can directly affect the leakage of the flange joint, and the creep relaxation is rapid, the greater the possibility of leakage.
4. Medium resistance
Media resistance is also an important parameter for the sealing material of non-asbestos gaskets. The formula of the material is directly related to the size of the media resistance, it is a manifestation of the resistance to the media. It includes chemical resistance, oil resistance and solvent resistance. The general medium refers to water, oil, salt, etc. With the change of time, the thickness and weight of the material will increase, and it will stabilize at some point. Therefore, the thickness increase rate and weight increase rate of the material can be used to indicate the size of the dielectric resistance, and its size also directly determines the material. For what kind of environment.
5. Sealing performance
To a certain extent, the sealing performance can be used to evaluate the comprehensive performance of Bird's asbestos-free gaskets. It is a collection of the previous properties. A good sealing performance means that the gaskets have good comprehensive performance, and vice versa. The leak rate is one of the most intuitive parameters to show the quality of the sealing performance. The sealing performance of non-asbestos gaskets is not only closely connected with the actual situation, but also related to the thickness of the gasket, bolt torque and assembly method.
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The plug valve is a fast-opening and straight-through valve. Because the movement between the rotary sealing surfaces has a wiping effect, and when it is fully opened, it can completely prevent contact with the flowing medium, so it can usually be used for medium with suspended particles. Another important feature of it is that it is easy to adapt to the multi-channel structure, so that one valve can obtain three or even four different flow channels. This can simplify the design of the piping system, reduce the amount of valves and some connecting accessories required in the equipment.
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