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Packing seals feature a wide range of available packing materials, easy processing, low cost, reliable sealing performance, and simple operation, which gives them a broad range of applications. In recent years, with the development of sealing gaskets, gasket seals have seen significant improvements in terms of materials, structural design, and various other properties. As a result, they are being used more widely in the machinery industry, yielding good economic benefits. 1 Working mechanism of packing seals. In the machinery industry, packing seals are primarily used as dynamic seals. It is commonly used for sealing the shafts of centrifugal pumps, compressors, vacuum pumps, and mixers. When designing a packing seal, the operating conditions of the mechanical equipment should be the main consideration; the packing selected should meet the following requirements: (1) It should possess a certain degree of plasticity, so as to generate a certain radial force under compression and make contact with the shaft. (2) It has sufficient chemical stability, does not contaminate the medium, the filler is not swollen by the medium, the impregnant in the filler is not dissolved by the medium, and the filler itself does not corrode the sealing surface. (3) The filler has good self-lubricating properties, is wear-resistant, and has a low coefficient of friction. (4) When there is a slight offset in the shaft, the packing should have sufficient floating elasticity. (5) Simple manufacturing and easy filling. For this reason, it is necessary to regularly adjust the degree of compression of the filler, so that after some lubricant is lost over time due to operation, more lubricant can be extruded to compensate for the reduction in compression force caused by changes in the filler’s volume. Of course, constantly compressing the filler in this way will eventually deplete the impregnant, so it is necessary to replace the filler regularly. Furthermore, to maintain the liquid film and remove frictional heat, it is also necessary to allow a small amount of leakage at the packing. 2 Problems of packing in the use of water pumps: The shaft seals of water pumps generally use oil-impregnated asbestos packing or oil-impregnated cotton yarn packing. Oil-impregnated asbestos packing has advantages such as heat resistance, good flexibility, and high strength, but it also has fatal drawbacks: its surface becomes rough after being woven, it has a high coefficient of friction, and leakage can occur; furthermore, the lubricant absorbed into it tends to be lost over time. Oil-impregnated cotton bobbins become very hard when soaked in water for a long time, and due to their high coefficient of expansion, they exhibit high friction. In actual production, it is common for newly installed equipment to have good shaft seal performance at the start of operation; however, after a short while, the leakage increases steadily. Adjusting the gland and replacing the packing becomes more frequent over time. Before even one operating cycle is completed, the shaft sleeve can become worn into a vase shape. In severe cases, the shaft sleeve may even break, and the packing material located behind the water seal ring rots and can no longer provide a proper seal. Generally speaking, packing has the following disadvantages: (1) The packing is in direct contact with the shaft and rotates relative to it, which causes wear on the shaft and the sleeve; therefore, the sleeve must be replaced periodically or as needed. (2) In order to allow the frictional heat generated between the packing and the shaft or sleeve to dissipate promptly, the packing seal must allow a certain amount of leakage, and this is difficult to control. (3) Friction between the packing and the shaft or shaft sleeve reduces the motor’s effective power, resulting in energy waste; in some cases, this loss can reach an astonishing rate of 5%–10%. Overall, packing materials have the following disadvantages: Based on the principle of packing seals, there are three possible pathways for fluid leakage within the sealing chamber; one of these is fluid penetrating the fibrous material, resulting in leakage ； The second is leakage between the filler and the filler box ； Third is leakage between the filler and the shaft surface. Therefore, the most crucial measure to prevent water pump leakage is: (1) properly selecting the sealing packing ； (2) Design a reasonable sealing chamber and adjust the appropriate sealing compression force. 3 Design of the combined soft packing seal. The structure of the packing chamber designed is shown in Figure 2. The filler chamber is filled with an excellent sealing soft material, which is composed of carbon fiber, high-purity graphite, polytetrafluoroethylene, organic sealants, and other components. It can withstand temperatures ranging from -18°C to 200°C, with a maximum pressure of 0.7 Mpa and a maximum linear velocity of 8 m/s. It has strong corrosion resistance; the suitable pH range for the media it works with is 4–13, and it is mainly suitable for use with water-based media. In this soft filler state, it is in a paste-like form, with a low friction coefficient and weak molecular attraction between the components. During the rotation of the shaft, the fibers in the packing wrap around the shaft and rotate together with it, forming a \"rotating layer\". This \"rotating layer\" serves to protect the shaft or bearing sleeve, preventing wear on the bearing sleeve and reducing power consumption ； As the diameter of the \"rotating layer\" increases, the axis’s ability to wrap around the fibers gradually diminishes; the fibers no longer wrap around the axis and remain relatively stationary against the inner wall of the filler chamber, thus forming a \"shear layer\" within that chamber. At this point, the area where frictional shear occurs due to relative rotational motion is located within the filler itself, rather than between the filler and the axis. In addition, polytetrafluoroethylene braided packing is pressed at both ends of the inserted packing, and the end rings of this braided packing are used to compress the mixed soft packing. To prevent the mixed packing from being squeezed out during high-speed rotation of the shaft, spiral grooves are intentionally designed and fabricated in the packing chamber and at the gland. It is important to note that the directions of the spiral grooves at both ends of the packing should be opposite to each other; this ensures that as the shaft rotates, an inward pumping action is generated on the mixed packing, effectively preventing it from flying out. 4 Pump testing: After the combined packing was designed and manufactured, tests were conducted on the pump testing bench. The design operating conditions of the test bench are as follows: motor speed of 1500 r/min, working pressure of 1 MPa, medium being clean water, and medium temperature at room temperature. The packing filling process is carried out according to the following steps: (1) Clean the packing chamber, and check whether there are any scratches or burrs on the surface of the shaft, ensuring that the roughness of the shaft meets the requirement of Ra1.6 as specified in the drawings ； (2) Use a dial indicator to check the radial runout of the shaft at the sealing area; the tolerance should be within the range of 0.03mm–0.08mm. (3) When loading, it is best to first use a wooden rod of the same size as the shaft; wrap the knitted PTFE around this rod and then cut it using a knife. The cut should be made at a 45º angle. Use two wooden half-shaft sleeves of the same size as the filler chamber, fit them over the shaft, and push the knitted filler deep into the chamber. Apply pressure to these wooden sleeves with a gland in order to pre-compress them, making sure that the knitted filler remains flat at the bottom of the chamber. (3) When injecting the mixed clay-like filler, it must be compressed simultaneously with the use of a wooden sleeve; afterward, braided polytetrafluoroethylene is placed over the outside of the filler chamber, and the gland is tightened evenly. At the same time, the main shaft is rotated by hand to ensure that the compressing force after filling follows a parabolic distribution. Finally, the gland is slightly loosened, completing the filler filling process. During operation tests, at the beginning of operation, the leakage was mainly in the form of intermittent drips; when the leakage increased, the gland bolts were tightened appropriately. If the temperature is too high, loosen the bolt slightly. Once it was running properly, the leakage basically stopped. After 60 hours of trial operation, the packing seal chamber was opened for inspection; the braided polytetrafluoroethylene end ring retained its intact shape, the mixed soft packing showed no signs of damage, and there were no signs of wear on the shaft. 5 Conclusions (1) The combined soft packing effectively improved the mechanical efficiency of the pump and reduced wear on the shaft. The filler gland can remain leak-free for a long time, thus protecting the environment. (2) It is easy to maintain; when there is a large amount of leakage, packing can be added without shutting down the pump, which extends its continuous operating time and saves on labor and maintenance costs. Preliminary estimates suggest that the energy savings amount to over 10,000 yuan per pump per year. (3) Modular soft packing has broad application value.