Ningbo Boman Mechanical & Technology Co.,Ltd
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What is an O-ring ?

O-ring is a cross-section of a circular rubber ring, its cross-section for O-, it called for the O-ring, also known as O-ring.
O-ring What are the advantages?


O-ring has the following advantages compared with other types of seals: one for the form of a variety of sealing: static seals, dynamic seals, suitable for various uses materials, dimensions and grooves have been standardized, strong interchangeability fit a variety of Exercise: rotary motion, axial reciprocating motion or a combination of movements (for example, rotating back and forth combined motion) 3 suitable for a variety of different sealing medium: oil, water, gas, chemical media or mixed media. Through the appropriate choice of rubber materials and the appropriate formula to achieve an effective seal for oil, water, air, gas and various chemical media. Wide temperature range (- 60 ℃ ~ + 220 ℃), fixed using pressure up 1500Kg/cm2 (with reinforcing ring and use). 


simple design, compact structure, easy assembly and disassembly. O-ring cross section structure is extremely simple, and self-sealing, sealing performance and reliable. O-ring and install parts of the structure is extremely simple, and the formation of standardization, so are very easy to install replacement. Variety of materials. Can be selected depending on the fluid: nitrile rubber (NBR), Viton (FKM), silicone rubber (VMQ), B-propylene rubber (EPDM), chloroprene rubber (CR), butyl rubber (BU), poly tetrafluoroethylene (PTFE), low cost of natural rubber (NR) 6, 7, the dynamic frictional resistance is relatively small.



o-ring

O-ring is the main failure reasons for that?



A permanent deformation. Synthetic rubber O-ring materials are viscoelastic materials, so the initial set of compression capacity and resilience to clogging by the use of long, permanent deformation gradually be lost, and eventually leak. Permanent deformation and elastic disappearance of the O-ring main reason for loss of sealing performance. 2 gap bite. The existence of geometric accuracy (roundness, ovality, cylindricity, concentricity, etc.) bad sealed parts, the parts between the different heart and under high pressure inner diameter swell phenomenon, will lead to the expansion of the sealing gap and gap extrusion the intensification of the phenomenon. Also have a significant impact on the hardness of the O-ring gap extrusion phenomenon. The higher the pressure of liquids or gases, the smaller O-ring material hardness, the gap of the O-ring extrusion phenomenon is more serious. Distortions. Distortions refers to the phenomenon of the O-ring torsion along the circumference, the distortions that generally occurs in the state of dynamic seal. O-ring assembly proper, and appropriate conditions of use are generally not easy to scroll back and forth in a reciprocating motion state or distorted, because the contact area of the O-ring groove is greater than the friction on the sliding surface contact area, and O-ring resistance capacity of the original will be able to prevent distortion. The distribution of friction tends to keep the O-ring in its groove, stationary, static friction greater than sliding friction, and the groove surface roughness is generally not as good as the roughness of the sliding surface. 


What should be noted for choose o ring ? 



Select O-ring, consider the following points: 1) O-ring state: This is the O-ring for static sealing or for dynamic sealing, sliding or rotating. 2) Mechanical work status: the machinery is in contact or intermittent work, and should consider the length of each intermittent, impact load acting on the sealing parts. 3) the situation of the working medium: the working medium is liquefied or gas, and consider their physical and chemical properties. 4) Working pressure: the size of the pressure fluctuations in amplitude and frequency, and suddenly come upon pressure.


The development of the O-ring:



  1. The improvement of the O-ring shape with the improvement of sealing performance requirements, and now there have been some other cross-section shape of the extrusion-ring, the working principle is similar to the O-ring seals, also belong to squeeze seal, but through the cross-section shape change, to improve some of the performance of the O-ring. 


  2. X-ring X-ring (also known as the star circle) is a four-lip seal. It is a ring without joints, curing in the mold forming the cross-sectional approximate square. X-ring on the use and role very much like the O-ring. However, it is more effective than the O-ring sealing performance. The production of the X-ring material for a variety of synthetic rubber. 


  3. The cross sectional shape of extrusion-ring (1) D-ring ② ordinary triangular cross-section circle ③ star ring.  PTFE O-ring PTFE O-ring than the ordinary rubber material made of O- ring temperature adaptability, its temperature range is -40 ~ 250 ° C; and resistance generally concentrated acid (eg sulfuric acid, nitric acid), concentrated alkali and organic solvents (such as acetone, ketones) performance. Phosphate ester fire resistant hydraulic oil used in order to fire retardant media in hydraulic equipment in recent years due to the PTFE from the erosion of this hydraulic fluid, it is appropriate to do this sealing material of the medium.


  4. The encapsulation type so-called entrapment of the O-ring O-ring O-ring is the one with its own different materials coated live, so that the characteristics of the two materials. This encapsulation type O-ring comes in many forms. Which coated PTFE O-ring most frequently used