Introduction to the performance requirements and technical requirements of mechanical seals

Mechanical seal performance requirements and technical requirements This requirement applies to centrifugal pumps and other similar rotary mechanical seals. The working parameters are: the working pressure is 0---1.5691MPa (referring to the actual pressure in the sealing cavity) The temperature is -20--80°C (referring to the actual temperature in the sealing chamber), the outer diameter of the shaft (or shaft sleeve) is 10-120mm, the speed is not more than 3000r/min, and the medium is clean water, oil and general corrosive liquids.u200bu200b
First, the performance requirements of mechanical seals:
1. Leakage. When the medium to be sealed is liquid, the average leakage is specified as follows: when the outer diameter of the shaft (or bushing) is greater than 50mm, the leakage is not greater than 5mL/h; when the outer diameter of the shaft (or bushing) is not greater than 50mm, the leakage is not greater than 50mm. More than 3mL/h. It is not limited for special conditions and when the sealed medium is gas.u200bu200b
2. Wear amount. The amount of wear should meet the requirements of the service life of the mechanical seal. Usually, the test is carried out 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.u200bu200b
3. Under the condition of reasonable selection and correct installation and use, when the sealed medium is clean water, oil, non-corrosive and similar medium, the service life of the mechanical seal is generally not less than one year, and the sealed medium is In corrosive media, the service life of the mechanical seal is generally half a year, but it is not limited when the use conditions are harsh.u200bu200b
4. The test pressure of the static pressure test of the mechanical seal is 1.25 times of the maximum acting pressure of the product, and it lasts for 15 minutes. The outer diameter of the shaft sleeve) is not more than 50mm, and the converted leakage is not more than 3mL/h.

Second, the technical requirements of the main parts of the mechanical seal:
1. The flatness and roughness of the sealing end face require that the deviation of the flatness of the sealing end face is not greater than 0.0009mm; the maximum allowable value of the roughness R of the sealing end face of metal materials is 0.2μm, and the maximum allowable value of end face roughness R of non-metallic materials is 0.4 μm.u200bu200b
2. The parallelism of the sealing end faces of the stationary ring and the rotating ring to the end face contacting the auxiliary sealing ring shall be in accordance with the grade 7 tolerance of GB 1184-80 'Shape and Position Tolerance - Regulations of Unmarked Tolerance'.u200bu200b
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 dimensional tolerance of the outer circle or inner hole is h8 or H8.u200bu200b
4. The verticality of the outer circle between the end of the static ring seal and the auxiliary seal of the static ring, and the verticality of the inner hole of the rotary ring seal to the contact of the auxiliary seal of the rotating ring are all in accordance with GB 1184--70 7 level tolerance.u200bu200b
5. Graphite ring, filled PTFE ring and assembled rotating ring and static ring should be tested by hydraulic pressure. Test 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 10min.u200bu200b
6. Tolerance values u200bu200bsuch as inner diameter, outer diameter, free height, working pressure, and perpendicularity between the center line and the end face of the spring are all in accordance with the requirements of the first-class precision standard of the relevant national spring standards. For multi-spring mechanical seals, the free height difference between springs in the same set of mechanical seals shall not be greater than 0.5mm.u200bu200b
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.u200bu200b
8. For technical requirements of rubber O-ring, refer to relevant national standards.