Packing seal used in high temperature and high pressure. For example, oil-impregnated asbestos packing, sealing pressure up to 12 kg/cm, medium temperatures up to 250 degrees Celsius. But packing sealing speed is low. For example, when used in a pump, the use of maximum speed of 6 m/s. This is because packing packing do not wear, packing and the contact surface of the shaft is large, and packing pressure on the axis is also very large, thus heating and wear. If the sealing medium pressure is high, screw must also be more tightly, making packing axial clamping force larger, so that high pressure seal leakage. At this point, the low shaft speed must be reduced further. Visible, pressure and speed are related to each other, when the pressure is low, to allow high speed; if the pressure is higher, you must reduce speed in order to meet the requirements of high pressure seal. Reasons for leakage of packing seal, is the heat produced by friction, packing some components in volatile or carbide formation and leakage gap. At this point, the new packing can be replaced to restore its sealing properties. Packing costs are low, this is other than in all high pressure seal. However, the packing seals the size and weight of a large, much less compact, light graphite seal and piston ring seals.