There are many types of Fire Proof Seal, according to its working principle is divided into mandatory sealing and self close two categories. The forced seal relies on the preload of the connecting piece (bolt) to ensure the pressure vessel's top cover, the sealing element and the cylinder end have certain contact pressure to achieve the sealing purpose. Self-tightness sealing is the result of the increasing of pressure in pressure vessel, the contact pressure between sealing element and top cover and cylinder end is also increased, thus the sealing effect is realized. Self-sealing is characterized by higher pressure, sealing elements in the contact surface pressure is greater, sealing performance is better, operating conditions fluctuations, the seal is still reliable. But the structure is more complex and difficult to manufacture. Self-tightness sealing according to the deformation mode can also be divided into axial self tightness sealing and radial self tightness seal.
According to the performance of sealing materials, high pressure seals can be divided into plastic seals that make plastic deformation of sealing elements, so that the sealing elements produce elastic seals with elastic deformations.
At present, pressure vessels commonly used in the sealing types are as follows:
1 seal with flat gasket, Kazari seal and octagonal gasket seal;
2) semi-hermetic sealing with double cone;
3 from tightly sealed wedge-shaped seals, five German seals, hollow metal O-ring seals, C-ring seals, B-ring seals, triangular gasket seals, octagonal gasket seals, flat pads from tight seals and rubber O-ring seals.