How to install double-end machine seal
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There was a LPG pump machine in the workshop that had a broken seal. The main reason was that the inner layer of the machine seal was leaking. The outer seal was fine. It took the machine repairman two days to fix it. It was very mysterious. Please tell me how to replace this kind of seal. It is best for someone with experience to explain in detail. Do not search for a paragraph from the Internet and post it. Thank you.
Nowadays, double-end seals are basically cartridge-type. You can install them as a whole and remove the positioning piece. There is nothing mysterious about double seals. It is just a combination of two sets of sealing heads. Common double seals have three layout styles: series, face-to-face (the compensation ring is stationary), and back-to-back (the compensation ring rotates). The so-called compensation ring is a sealing ring together with an elastic mechanism such as a spring. The double seal close to the medium side is the main seal, and the one on the atmospheric side is the auxiliary seal, which plays the role of double insurance. Generally, leakage or failure on any side requires shutting down for maintenance and replacement. Generally, seals have 5 leakage points, namely, static ring and auxiliary sealing ring (commonly O-ring, the same below), dynamic and static ring sealing surfaces, dynamic ring and auxiliary sealing ring, equipment cavity and sealing end cover, and equipment shaft and sealing sleeve. Generally, the location of leakage is between the sealing surfaces, accounting for 90%, followed by the auxiliary seal of the moving ring, and there is basically no problem in other locations. As for the leakage of the inner seal (main seal) you mentioned, it is basically caused by the leakage of the sealing surface. But there are many reasons: 1) The sealing surface precision is not enough, that is, the flatness of the two sealing rings is unqualified. Generally, the roughness is required to be 0.2, and the flatness is within 3 light bands. It can be repaired by grinding again. ； 2) If the sealing surface has flaws such as cracks, missing edges, etc., it may be caused by transportation or installation problems. After operation, it may be caused by pressure or thermal cracking, etc., and it can only be replaced. ； 3) If there are errors in the selection and design parameters of the seal itself, it will usually leak when the vehicle is started and can only be replaced (there is no such reason for leakage after running for a long period of time). ； 4) Corresponding to metal parts problems, such as the uneven metal seat of the static ring causing the sealing ring surface to be non-parallel, etc., the metal parts need to be repaired ； 5) If you still have questions about other issues such as the material properties of the sealing ring, please contact me.
The person above explained it more thoroughly. For a relatively simple replacement, just install it in the reverse order of disassembly. Be careful not to hit the sealing surface. Also, you must keep it in its original position and don't change the amount of compression.
The sealing surface precision is not enough, that is, the flatness of the two sealing rings is unqualified. Generally, the roughness is required to be 0.2, and the flatness is within 3 light bands. It can be repaired by grinding again.； Want to get on the machine? Is sandpaper okay?