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JB/T 6619 Light mechanical seals is divided into two parts:
——Part 1: Specification;
——Part 2: Testing methods.
This standard is Part 1 of JB/T 6619.
This standard is prepared in accordance with the rules given in GB/T 1.1-2009.
This standard replaces JB/T 6619.1-1999 Specification for light mechanical seals, and the following technical changes have been made with respect to JB/T 6619.1-1999:
——The normative references have been modified, the listed standards are currently valid (see Clause 2, Clause 2 of Edition 1999);
——The technical requirements for rubber O-rings, rubber bellows and other rubber auxiliary seals have been added to the technical requirements for main components (see Clause 4);
——The leakage index has been modified (see 5.1, 3.3.2 of Edition 1999);
——The working life of the product has been modified (see 5.3, 3.3.1 of Edition 1999).
This standard is proposed by the China Machinery Industry Federation.
This standard is under the jurisdiction of SAC/TC 491 National Technical Committee on Mechanical sealing of Standardization Administration of China.
The previous editions of this standard are as follows:
——ZB J22 005-1988;
——JB/T 6619.1-1999.
Light Mechanical Seals Part 1: Specifications
1 Scope
This part of JB/T 6619 specifies the light mechanical seal structure, technical requirements for main components, performance requirements, inspection rules, test methods, installation and usage requirements, marking and packaging.
This standard applies to light mechanical seals for small (of power less than 7.5 kW) centrifugal pumps, vortex pumps, rotor pumps, jet pumps and other similar rotating machinery.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 1184-1996 Geometrical tolerancing—Geometrical tolerances for features without individual tolerance indications
GB/T 2828.1-2012 Sampling procedures for inspection by attributes—Part 1: Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection
JB/T 6374 Specification for silicon carbide rings of mechanical seal
JB/T 6619.2 Light mechanical seals—Part 2: Test methods
JB/T 7757.2 The rubber O-ring for mechanical seal
JB/T 8872 Specification for carbon-graphite sealing ring for mechanical seals
JB/T 10874 Specification for alumina ceramics rings of mechanical seal
JB/T 11107 Cylindrically helical compression spring for mechanical seal
JB/T 11242 Automotive engine cooling water pump mechanical seal
JB/T 11959 Sealing ring of cemented carbide for mechanical seal
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3 Light mechanical seal structure
This standard does not make specific provisions on the structure of light mechanical seals. Each manufacturer may design light mechanical seals with different structures according to the user's operating conditions. The mechanical seal's working parameters are generally as follows; the pressure of the sealing chamber is 0~0.5 MPa; the temperature of the sealing chamber is 0°C~100°C; the average linear velocity of the sealing end face is not greater than 10 m/s; the diameter of the sealing shaft is not greater than 40 mm; the medium is water, oil and other liquids with low corrosion.
4 Technical requirements of main parts and components
4.1 Sealing ring
4.1.1 The flatness requirements of the sealing end face of the sealing ring: the flatness error of the hard sealing ring of the light mechanical seal shall not be greater than 0.0006 mm, and the flatness error of the soft sealing ring shall not be greater than 0.0009 mm.
4.1.2 Requirements for the surface roughness of the sealing end face of the sealing ring: the surface roughness Ra of the hard sealing ring for the mechanical seal of the automotive engine cooling water pump shall not be greater than 0.2 μm; the surface roughness Ra of the soft sealing ring shall not be greater than 0.4 μm. The surface roughness Ra of sealing ring of cemented carbide for light mechanical seal shall not be greater than 0.1 μm, and the surface roughness Ra of the soft sealing ring shall not be greater than 0.2 μm.
4.1.3 The sealing end face of the sealing ring shall be free from scratches, pores, cracks and other defects on the substrate.
4.1.4 The parallelism of the sealing ring with the sealing end face and the positioning end face in contact with the auxiliary seal shall meet the requirements of grade of tolerance 7 specified in GB/T 1184-1996.
4.1.5 The verticality of the sealing end of the stationary or rotating ring to the outer circle or inner bore in contact with the auxiliary seal of the ring shall meet the requirements of grade of tolerance 7 specified in GB/T 1184-1996.
4.1.6 The surface roughness Ra of the part where the sealing ring is in contact with the auxiliary seal shall not be greater than 1.6 μm.
4.1.7 Cemented carbide sealing ring, silicon carbide sealing ring, carbon graphite sealing ring and alumina ceramic sealing ring shall meet the requirements of JB/T 11959, JB/T 6374, JB/T 8872 and JB/T 10874 respectively.
4.1.8 The compensation ring assembly shall be able to move freely along the axial direction without blocking.
4.2 Springs
The size, precision and working load of springs shall meet the requirements of JB/T 11107. Rust spots are not allowed on the surface of the spring. For coated springs, the coating must not come off.
4.3 Rubber bellows
The design of rubber bellows shall ensure the reliability of sealing and torque transmission. The surface of rubber bellows and other rubber auxiliary seals shall be smooth and flat without any bubbles, slag inclusions or unevenness, and there shall be no flash in the sealing part. The physical and chemical properties of the rubber compound and appearance specifications of rubber components shall meet the requirements of JB/T 7757.2.
4.4 Rubber O-rings
The technical requirements of rubber O-rings shall comply with the provisions of JB/T 7757.2.
4.5 Stampings
Stampings shall not have burrs, wrinkles, rust spots, etc., and there must be no longitudinal stripes in the sealed part. Coated stampings are not allowed to peel off the coating.
5 Property requirements
5.1 Leakage
There shall be no visible air bubbles in the air tightness test.
Leakage of static pressure test and running test: the leakage rate of mechanical seal for electric submersible pumps shall not exceed 0.1 mL/h, the leakage of mechanical seal for automotive engine cooling water pump shall comply with the provisions of JB/T 11242, and the leakage of mechanical seal for other pumps shall not exceed 2 mL/h.
5.2 Abrasion loss
The abrasion loss shall meet the requirements of its service life, and the test shall be carried out in clean water. After running for 100 hours, the abrasion loss of the sealing ring of the soft material shall not be greater than 0.02 mm.
5.3 Service life
In the case of reasonable selection and correct installation and use, the service life of the light mechanical seal shall not be less than 8,000 h. When used in special conditions, the service life is determined by the buyer and the seller through negotiation.
Foreword i
1 Scope
2 Normative references
3 Light mechanical seal structure
4 Technical requirements of main parts and components
4.1 Sealing ring
4.2 Springs
4.3 Rubber bellows
4.4 Rubber O-rings
4.5 Stampings
5 Property requirements
5.1 Leakage
5.2 Abrasion loss
5.3 Service life
6 Inspection regulations
6.1 Classification
6.2 Appraisal inspection
6.3 End-of-manufacturing inspection
7 Test method
8 Requirements for installation and use
9 Marking and packaging
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