Issues regarding vertical vibration of centrifugal pumps and similar problems
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Who can provide the standard requirements for shaft runout, verticality, and concentricity of the pump at the location where the mechanical seal is installed? I would also like to know to what extent these three criteria affect the mechanical seal – does exceeding these standards lead to leakage immediately, or does it only affect the lifespan of the mechanical seal?
1. The shaft runout tolerance is no more than 0.04 mm. 2. The maximum tolerance for perpendicularity shall not exceed 0.005 mm every 10 mm of the seal chamber diameter. 3. The maximum coaxiality tolerance shall not exceed 0.13 mmFIM. 4. The shaft runout shall not exceed 0.3 mm.
Excessive radial runout of the pump shaft can cause problems with the sealing surfaces of the mechanical seal, while excessive verticality can reduce the seal’s service life; in some cases, uneven stress on the soft rings can lead to their failure and thus direct leakage； Excessive concentricity can also affect the seal life
Of course, some mechanical seals are packaged in such a way that the moving and stationary rings cannot be seen, making overall disassembly necessary； Some are not in a modular design; the rotating and stationary rings as well as the spring seats can be seen after the main unit is disassembled. In the case of non-enclosed seals, when the concentricity, verticality, or coaxiality are out of specification, removing the seal after it has been in use for some time reveals that the wear marks on the sealing surface are wider than those on the contact surfaces of the rotating and stationary rings. This situation results in no leakage when the shaft is not rotating, but continuous leakage once it starts to rotate.