2. Cone seal: Making the sealing surface conical to narrow the contact surface. This kind of seal under the action of a certain sealing force, its sealing specific pressure is greatly increased, and it is easy to achieve the seal. Under the premise of ensuring sealing, the sealing force applied is smaller than that of flat seals. Since the narrow sealing surface is not easy for the disc to fall correctly on the valve seat, the disc must be guided in order to achieve the best sealing performance. After the disc is guided, it can achieve better sealing performance.