Packing Seal

Packing seal can be used for high temperature and high pressure. For example, oil-immersed asbestos packing, its sealing pressure can reach 12 kg/cm, the medium temperature can reach 250℃. However, the sealing speed of the packing is lower. For example, when used for water pumps, the maximum speed of use is 6 m/s. This is because the packing is not wear-resistant, and the contact friction surface between the packing and the shaft is very large, and the pressure of the packing on the shaft is also very large, so the heat and wear are serious. If the pressure of the sealing medium is higher, the screw must be tightened more tightly, so that the compression force of the disc shaft is greater, so as to ensure that the high pressure seal is not leaked. At this point, the speed of the shaft must drop even lower. It can be seen that the pressure and speed are related to each other, when the pressure is low, the speed can be allowed to be higher; If the pressure is high, the speed must be reduced to meet the requirements of high pressure sealing. The reason for the leakage of the general packing seal is that the friction produces high temperature, which causes some components in the packing to volatilize or carbonize and form a leakage gap. At this time, a new packing can be replaced to restore its sealing performance. The cost of packing is very low, which is not as good as other high-pressure seals. However, the volume and weight of the packing seal is very large, and it is far less compact and lightweight than the graphite seal and the expansion ring seal.