Ruichen Seals' basic hydraulic seals mainly include several types of seals, each with its own advantages. O-rings are widely used in various dynamic and static sealing occasions due to their low manufacturing cost and convenient use. Most countries have formulated a series of product standards for O-rings, among which the American standard (AS568), the Japanese standard (JISB2401) and the international standard (ISO 3601/1) are more common. The national standards are GB3452.1 and GB1235.
The star-shaped seal ring is a four-lip seal with an X-shaped shape, so it is also called an X-shaped ring. It is an improvement and enhancement based on the O-ring. Its cross-sectional dimensions are the same as the O-ring of the US AS 568A standard, and it can basically replace the use of the O-ring.
Advantages of star rings
Compared with O-rings, star rings have less friction resistance and less starting resistance because they form a lubricating cavity between the sealing lips. Because its flash edge is located in the concave part of the cross section, the sealing effect is better. The non-circular cross section effectively avoids the rolling phenomenon during reciprocating motion.
Star ring working mechanism
The star ring is a self-tightening double-acting sealing element. The radial and axial forces depend on the pressure of the system. As the pressure rises, the compression deformation of the star ring will increase, and the total sealing force will increase, thus forming a reliable seal.
How to choose a star-shaped seal ring
If the diameter of the shaft and hole is known, select the appropriate star-shaped seal ring according to the following criteria:
1. Static sealing or reciprocating linear motion: (1) Hole sealing: The inner diameter of the star-shaped ring should be compatible with the groove, or less than about 2% of the groove bottom diameter. Because the pre-compression force generated by pre-compression can effectively prevent the star-shaped seal ring from twisting and rolling. (2) Shaft sealing: The inner diameter of the star-shaped ring should be equal to or appropriately larger than the outer diameter of the shaft by about 0.2~0.3mm, or it can be about 1% larger than the outer diameter of the shaft. As a result, the seal ring will be easier to install and have a longer service life.
2. Rotary sealing: The inner diameter of the star-shaped ring should be about 2~5% larger than the diameter of the shaft it seals. Because the seal ring will generate friction and heat when used in a rotating motion, and the rubber will shrink when heated (Joule effect). Therefore, in order to ensure that the seal ring can be lubricated and work reliably, a star-shaped ring with an inner diameter larger than the shaft diameter must be selected. Usually, a seal ring with a smaller cross-section can meet the needs of static sealing. On the contrary, a seal ring with a larger cross section should be selected to meet the dynamic seal. In the case of high pressure or large gaps, a rubber material with a higher hardness must be selected. The best way is to add a PTFE retaining ring to prevent high pressure extrusion damage.
The coated O-ring organically combines the elasticity and sealing of rubber with the chemical resistance of Teflon. It is composed of a silicone or fluororubber inner core and a relatively thin Teflon FEP or Teflon PFA outer coating.
Material: Teflon FEP and Teflon PFA are essentially similar, but Teflon PFA has better high temperature resistance than Teflon FEP. Applicable temperature range Teflon FEP shell: -60℃~205℃ Can be used at 260℃ for a short time Teflon PFA shell: -60℃~260℃ Can be used at 300℃ for a short time Advantages:
1. Outstanding chemical resistance, suitable for almost all chemical media
2. Wide temperature range
3. Good compression resistance
4. Anti-friction
5. Good anti-swelling
6. High pressure resistance
7. Excellent sealing durability and long service life
Application: pumps and valves, reaction vessels, mechanical seals, filters, pressure vessels, heat exchangers, boilers, pipeline flanges, gas compressors, etc.
Application industries: chemical industry, aircraft manufacturing, pharmaceutical industry, oil and chemical transportation and refining, film industry, refrigeration engineering, food processing industry, papermaking industry, dye manufacturing, paint spraying, etc.
Installation instructions for sealing rings
1. The parts where the sealing rings are installed or passed through must be smooth, free of burrs, grooves and sharp corners. The roughness of the inner hole should reach 1.6μ and the roughness of the shaft should reach 0.8um.
2. Apply clean light oil or grease to lubricate the surface of the sealing ring and the relevant parts in contact.
3. If it is difficult to install the sealing ring on the shaft, immerse it in hot water for a few minutes to expand it. This softened and expanded O-ring is easier to install. Install the O-ring when it is hot, and its size will return to its original size after cooling down.
4. Do not bend the O-ring too violently, otherwise it will cause wrinkles in the Teflon and affect its use.
The recommended compression of the coated O-ring is as follows:
Static sealing state: 15%-20%
Dynamic sealing state: 10%-12%
Pneumatic state: 7%-8%
The actual compression should take into account the working conditions, especially the sealing working pressure and other factors.
Product features and applications:
| O-ring performance parameter table |
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Static seal | Dynamic seal |
| Working pressure | Without retaining ring, 20MPa max With retaining ring, 40 MPa max, special retaining ring 200MPa max | Without retaining ring, 5MPa max With retaining ring, higher pressure |
| Speed | Reciprocating 0.5m/s max, rotating 2m/s max | |
| Temperature | General use: -30～+110, special rubber: -60～+250, rotating: -30～+80 | |
| Medium | See materials section | |
| Standard | O-ring cross-section diameter W |
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| American Standard AS 568 British Standard BS 1516 | 1.78 | 2.62 | 3.52 | 5.33 | 6.99 | - | |
| Japanese Standard JIS B2401 | 1.9 | 2.4 | 3.1 | 3.5 | 5.7 | 8.4 | |
| International standard ISO 3601/1 German standard DIN 3771/1 Chinese standard CB 3452.1 | 1.8 | 2.65 | 3.55 | 5.30 | 7.00 | - | |
| Preferred metric sizes | 1.0 | 1.5 | 2.0 | 2.5 | 3.0 | 3.5 | |
| 4.0 | 4.5 | 5.0 | 5.5 | 6.0 | 7.0 | ||
| 8.0 | 10.0 | 12.0 |
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| American Standard AS 568 (900 Series) | 1.02 | 1.42 | 1.63 | 1.83 | 1.98 | 2.08 | |
| 2.21 | 2.46 | 2.95 | 3.00 |
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| The application range of star rings is very wide. Choose the right material according to the temperature, pressure and medium. In order to adapt the star ring to a given application, the mutual constraints between all working parameters should be considered. When determining the application range, the peak temperature, continuous working temperature and operating cycle must be considered. In rotating applications, the temperature rise caused by friction heat must also be considered. | |||||
| Technical Parameters | Dynamic seal | Static seal |
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| Reciprocating motion | Rotational motion |
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| Working pressure (MPa) | With retaining ring | 30 | 15 | 40 |
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| Without retaining ring | 5 | - | 5 |
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| Speed (m/s ) | 0.5 | 2.0 | - |
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| Temperature (℃) | General occasions: -30℃~+110℃ |
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| Special materials: -60℃~+200℃ |
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| Rotation occasions: -30℃~+80℃ |
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Star ring material:
The material is generally Shaw A70 nitrile rubber NBR.
Coated O-ring:
Schematic diagram of the groove of the encapsulated O-ring
Dimension table of the groove of the encapsulated O-ring (recommended)
| Wire diameter d | A(mm) | B(mm) | ||
| Static seal | Dynamic seal | Pneumatic seal | ||
| 1.78 | 2.36/2.49 | 1.42/1.52 | 1.55/1.60 | 1.63/1.65 |
| 2.62 | 3.56/3.68 | 2.08/2.21 | 2.29/2.36 | 2.39/2.44 |
| 3.53 | 4.75/4.88 | 2.82/3.00 | 3.10/3.18 | 3.22/3.28 |
| 5.33 | 7.14/7.26 | 4.27/4.52 | 4.67/4.80 | 4.90/4.95 |
| 6.99 | 9.63/9.65 | 5.59/5.89 | 6.15/6.27 | 6.43/6.48 |
Ruichen Seal PTFE Seal Installation Guide
Ⅰ. Installation Guide
1. The seal must be installed on the preloaded side, facing the pressure direction.
2. The cylinder body and piston rod must be made with push-in chamfers that meet the requirements of our company's samples.
3. Sharp edges must be free of burrs and rounded or chamfered.
4. Threads, guide ring grooves, etc. should be covered, because the seal cannot be pushed through grooves, drilled holes or rough surfaces.
5. Any dust, debris or other foreign particles must be carefully removed.
6. Tools with sharp edges should not be used.
7. PTFE sealing rings are easier to expand in heated oil or water (about 80~120 degrees) and are easy to restore to their original shape.
8. If the lip of the seal needs to pass through the oil pressure hole, a plastic stick should be used to gently push the lip to prevent the chamfer of the hole from damaging the sealing lip. The holes of the cylinder should be chamfered. (Figure 3)
Ⅱ. Installation method
Open (split) grooves can be installed without tools.
Installation of closed groove piston rod seals (Figure 1)
1. Clean and oil all seal substrates, seals and installation tools.
2. Place the rubber ring into the groove (be careful not to twist it).
3. Compress the PTFE seal ring into a kidney shape without forming a pointed bend, place the compressed PTFE seal ring into the groove, and gently flatten it by hand.
4. Push the recovery mandrel to the seal and gently turn the mandrel. Leave it for 1 minute and remove the mandrel. Installation is complete.
Installation of piston seals in closed grooves (Figure 2)
1. Clean and oil all seal substrates, seals and installation tools.
2. Place the rubber ring into the groove (be careful not to twist it).
3. Push the PTFE sealing ring onto the guide sleeve and stretch the sealing ring.
4. Push the stretched sealing ring into the piston groove.
5. Push the correction sleeve to the sealing ring and rotate the correction sleeve at the same time. Remove the correction sleeve after leaving it for 1 minute and the installation is complete.
Note: 1. Please consult our company if the product specified in our company's sample cannot be installed in a closed groove but is not suitable for an open groove.
2. The above installation of PTFE seals is not applicable to all PTFE seals. Please consult our company if necessary.
Address
No.1 Ruichen Road, Dongliuting Industrial Park, Chengyang District, Qingdao City, Shandong Province, China
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