Author:Site Editor Publish Time: 2020-12-21 Origin:Site
This requirement applies to centrifugal pumps and other similar rotary mechanical seals. The working parameters are: working pressure is 0---1.5691MPa (referring to the actual pressure in the sealed cavity); working temperature is -20--80℃ (referring to the actual internal temperature of the sealed cavity); the outer diameter of the shaft (or sleeve) is 10-120mm; the speed is not more than 3000r/min; and the medium is clean water, oil and general corrosive liquids.
1. The amount of leakage. When the sealed medium is liquid, the average leakage is specified as follows: when the outer diameter of the shaft (or sleeve) is greater than 50mm, the leakage is not more than 5mL/h; when the outer diameter of the shaft (or sleeve) is not more than 50mm, the leakage is not More than 3mL/h. For special conditions and when the sealed medium is gas, it is not limited.
2. The amount of wear. The amount of wear must meet the requirements of the mechanical seal's service life. The test is usually conducted with clean water as the medium, and the wear amount of the sealing ring of the soft material for 100h is not more than 0.02mm.
3. In the case of reasonable selection and correct installation and use, and the sealed medium is water, oil, non-corrosive and similar media, the service life of the mechanical seal is generally not less than one year. When the sealed medium is corrosive, the service life of mechanical seal is generally half a year. But it is not limited when the service conditions are harsh.
4. In the static pressure test of the mechanical seal, the test pressure is 1.25 times of the maximum pressure of the product, and it lasts 15 minutes. The indicator is that the outer diameter of the shaft (or sleeve) is greater than 50mm, and the converted leakage is not more than 5mL/h. The outer diameter of the shaft (or sleeve) is not more than 50mm, and the converted leakage is not more than 3mL/h.
1. The flatness and roughness requirements of the sealing end face
The flatness deviation of the sealing end surface is not more than 0.0009mm. The maximum allowable value of the surface roughness R of metal materials is 0.2μm; the maximum allowable value of the surface roughness R of non-metallic materials is 0.4μm.
2. The parallelism between the sealing ends of the stationary ring and the rotating ring facing the end faces of the auxiliary sealing ring is in accordance with the 7-level tolerance of GB 1184-80 "Provisions for shape and position tolerances without tolerances".
3. The maximum allowable value of the surface roughness R of the contact part between the stationary ring and the rotating ring and the auxiliary sealing ring is 3.2μm, and the outer circle or inner hole size tolerance is h8 or H8.
4. The verticality of the outer circle of the stationary ring sealing end face and the auxiliary sealing ring of the stationary ring, and the verticality of the inner hole of the rotating ring seal to the auxiliary sealing ring of the rotating ring shall be in accordance with the 7-level tolerance of GB 1184-70.
5. The graphite ring, filled PTFE ring and assembled rotating ring and stationary ring shall be tested by water pressure. Inspection pressure: The sealing ring used for unbalanced mechanical seal is 0.9807MPa; the sealing ring used for balanced mechanical seal is 2.3536MPa, and there should be no leakage for 10 minutes.
6. Tolerance values such as spring inner diameter, outer diameter, free height, working pressure, spring centerline and verticality of the end face, are in accordance with the requirements of the first-level precision standard of the relevant national spring standards. For multi-spring mechanical seals, the free height difference between the springs in the same set of mechanical seals is not more than 0.5mm.
7. The inner hole size tolerance of spring seat and transmission seat is F9, and the maximum allowable value of roughness R is 3.2μm.
8. The technical requirements of rubber O-rings shall refer to relevant national standards.
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