Due to varying operating conditions, there are many types of packing materials. To better distinguish and select packings, we typically classify them according to the material of the main sealing substrate:
1. Natural Fiber Packings
Natural fiber packings mainly include packings with natural cotton, hemp, wool, etc., as the sealing substrate.
2. Mineral Fiber Packings
Mineral fiber packings mainly include asbestos packings, etc.
3. Synthetic Fiber Packings
Synthetic fiber packings mainly include: graphite packings, carbon fiber packings, polytetrafluoroethylene (PTFE) packings, acrylic-silicone-reinforced fiber packings, etc.
4. Ceramic and Metal Fiber Packing
Ceramic and metal fiber packing mainly includes silicon carbide packing, boron carbide packing, and medium-alkali glass fiber packing. Since single-fiber materials all have inherent drawbacks, using a single fiber to weave packing can easily lead to leakage due to gaps between the fibers. Furthermore, some fibers have poor self-lubricating properties and high friction coefficients. Therefore, it is necessary to impregnate the packing with lubricants, fillers, and special additives to improve the packing's density and lubricity. Examples include mineral oil or molybdenum disulfide grease mixed with graphite powder, talc, mica, glycerin, and vegetable oil, as well as impregnation with polytetrafluoroethylene dispersion emulsions with appropriate amounts of surfactants and dispersants. Special additives typically include zinc microparticles, barrier agents, and molybdenum-based corrosion inhibitors to reduce the corrosion of equipment by the packing.
With the development of science and technology, the application of nanotechnology is becoming more and more widespread. Nanotechnology mainly explores some inherent hidden properties of materials. Some of these properties can reduce or eliminate some of the inherent drawbacks of materials and bring out some of the excellent properties of materials.
