Seals O Rings: Things You Need Know

Seals O Rings Things You Need Know

Sealing O-ring is a very inconspicuous spare part, even if you see it, we will ignore it, but it has great use. Whether it is daily necessities, medical equipment, or even industrial production, various media and movement conditions have the figure of the sealing O-ring so this article will take you to a comprehensive understanding of this always-overlooked spare parts.

What is an O-ring

Sealing O-rings are a commonly used sealing component, typically used to prevent leakage of liquids or gases and in fixed recesses inside machines to prevent displacement of components.

Seal O-ring is usually made of outstanding toughness material, divided into two categories static and dynamic, the requirements of the production of sealing O-ring material have good elasticity and durability, able to withstand strong pressure without deformation, even if the deformation can be restored to its original shape without destroying its original function.

In short, the excellent performance of O-rings is one of the preferred spare parts in a wide range of industries where sealing effectiveness is required. And as time goes by, O-rings have yet to be eliminated. With the advancement of technology, the development of O-rings – various types of rings Performance has also been improved.

figure 1 What is an O-ring

Advantages of O-Rings

O-rings are the preferred spare parts for sealing in many industries. They can withstand great pressure and maintain stable performance in extreme environments. The following are its outstanding advantages:

Strong sealing: O-rings have excellent elasticity and softness, good ductility, and high pressure resistance. They adapt to irregular surfaces of different materials, preventing leakage and ensuring efficient equipment operation.

Low Cost: Most o-rings are made of synthetic rubber for low manufacturing costs and long service life. They do not require frequent replacement and are relatively inexpensive to produce.

Easy installation: No other tools or experience are required to install the O-ring, and the installation is simple and easier to maintain.

Heat resistance: Many of the materials used in the production of sealing O-rings provide reliable service even at extreme temperatures (typically -50 to 120 degrees Celsius).

Good Chemical Properties: O-rings are resistant to oils, fuels, ozone, UV, and other chemicals, making them useful in a variety of industrial applications.

Wide range of applications: Due to their good physical and chemical properties, O-rings can be used in a wide range of fields such as transport, the medical industry, the chemical industry, the food industry and so on.

In short, these advantages of the O-ring is the key to its application in a variety of industries, and different production materials will strengthen and weaken some aspects of the advantages, so in the selection of O-rings must be based on the actual use of the O-ring material to select the O-ring, to play the O-ring’s maximum role.

figure 2 Advantages of O-Rings

What are O-ring seals used for

The common excellent characteristics of O-rings, such as high temperature resistance, high pressure resistance, high sealing performance, and the unique safety of certain materials, make O-rings exist in various industries. Some common industries are as follows:

Mechanical engineering: O-rings are commonly used to seal a variety of solids, gases and liquids in the use of various mechanical equipment to prevent leakage from affecting the operation of the machinery.

Pipe connection: O-rings can be used to seal the joints of pipes for various purposes, such as water pipes, air pipes, oil pipes, or pipes of different materials, such as plastic, stainless steel, etc., to ensure the sealing of the pipes.

Hydraulic and automotive systems: In hydraulic and automotive systems, some mechanical and pipeline connections such as hydraulic cylinders, hydraulic valves, etc. need to use o-ring connection sealing to prevent liquid leakage.

Automotive industry: O-rings are commonly used in automotive engines or hydraulic systems to seal out foreign objects such as water or oil without impeding the movement of the machine.

Aerospace: O-rings with high-pressure resistance are commonly used in aircraft, rockets and other equipment in the aerospace industry, where they can operate in high-pressure environments and even oxygen-deficient environments.

Food industry: O-Rings are safe and reliable materials that can be exposed to high temperatures and are used in the production of the food industry or in tableware that comes into direct contact with food, O-Rings are also often used for sealing isolation.

In short, O-rings have a variety of functions, and the production of O-rings and cost-effective materials, in many industries are applicable, but no matter in which industry to use, it is necessary to choose the right O-rings, in order to play out its maximum effectiveness.

figure 3 What are O-ring seals used for

Different O-ring seal materials

Sealing O-Rings can be made from a wide range of flexible materials. The international standard ISO 3601 contains a series of specifications for the materials used in O-Rings. ISO 3601-3 also classifies O-Rings into three grades: N, S, and CS. N is the acceptance standard for O-Rings, S denotes optimum performance in quality-critical industrial and aerospace applications, and CS denotes special and critical sealing applications, such as aerospace and other applications.

Depending on the temperature range, pressure strength, chemical compatibility and other requirements, you can choose the sealing o-rings made of materials suitable for your industry. The common materials used for seal o-rings are as follows:

Nitrile Rubber: This is a synthetic rubber, which can also be abbreviated as NBR. Sealing O-rings made of nitrile rubber are widely used in the industrial field, with excellent abrasion resistance, heat resistance and high elasticity.

Acrylic rubber: mainly made of acrylic ester polymerisation, referred to as ACM, has excellent heat resistance, oil resistance, ozone resistance and other characteristics, but compatibility with water and cold elasticity and nitrile rubber compared with a little worse.

Hydrogenated Nitrile: This is a special rubber material, also known as HNBR, is the product of hydrogenation of nitrile rubber, with good chemical resistance, tear resistance and other mechanical properties, good heat resistance, adaptable to temperatures of up to 150 ℃, as low as minus 48 ℃.

Ethylene Propylene Rubber: This is a synthetic rubber, which can be abbreviated as EPM or EPDM, is a copolymer of ethylene, propylene and diene monomers with an ethylene content of 45 to 75 per cent, and is incompatible with fats, oils, fuels and other mineral oil products. However, it has excellent heat, ozone, chemical and electrical insulation properties and is used in the automotive industry, electrical equipment and other areas.

Silica gel: a product of the synthesis of silicone, oxygen, hydrogen and carbon, abbreviated as VMQ, is colourless and odourless, has excellent sealing and bonding properties, which is why this material is also very common in life, such as in the medical and food industries, has very good temperature resistance, and is capable of static sealing at extreme temperatures, and is a commonly used material for producing sealing O-rings.

Fluoroelastomers and Perfluoroelastomers: Fluoroelastomers are made by the polymerisation of fluorine-containing hydrocarbon monomers, known as FKM, while perfluoroelastomers are a special type of fluoroelastomers, known as FFKM, which are superior in a variety of properties compared to fluoroelastomers, and are suitable for use in more extreme environments, for example, in the chemical industry, aerospace and some vacuum environments.

Fluorosilicone Rubber: It is a polymer made by polymerisation of fluorinated alkylsilane monomers, abbreviated FVMQ. It has excellent resistance to oils such as silicone oils and petroleum, as well as resistance to ozone and UV rays, and performs well in extreme temperatures, making it an excellent material for making sealing O-rings.

Butyl Rubber: It is a copolymer of isobutylene and a small amount of isoprene, IIR for short. its excellent elasticity and abrasion resistance make it widely used in the rubber products industry, and is also commonly used in the automotive or industrial sectors, and can also be used under high pressure or vacuum conditions.

Styrene-Butadiene Rubber (SBR): a polymer produced by the copolymerisation of butadiene and styrene, abbreviated as BR or SBR, with high flexibility and high impact strength, it is a commonly used production material in the rubber products industry, and also one of the commonly used materials for sealing O-rings.

Polyurethane: generated by the chemical reaction of isocyanate and polyol, referred to as AU, it has high elastic strength, extension and tensile strength, tearing degree, strong resistance to extrusion, etc., excellent characteristics and chemical properties so that it can be used as one of the materials for sealing O-rings.

In short, the materials used for sealing O-rings have good ductility, impact resistance, abrasion resistance and other basic characteristics, which can ensure the sealing of O-rings. How to choose the material needs to be based on what kind of environment you apply the O-ring, so according to their own needs to choose the right material to let the sealing O-ring to play its maximum role.

figure 4 Different O-ring seal materials

How to use O-ring seals

The appearance of O-ring is a cylinder surrounded by a ring, which occupies a very limited space, generally used in the combination of objects and objects, the space is small but enough to set into the O-ring. Coupled with the rubber itself, good elasticity, friction, so in the application of pressure, O-ring is squeezed deformation, O-ring and the formation of a high degree of friction between the object, so as to play a sealing role in the disappearance of the pressure, the O-ring can be restored to its original shape, so it can be reused, even in the dynamic space of the O ring can be deformed and restored between the rapid back and forth switching without destroying its good sealing performance. Even in dynamic space, O-rings can switch back and forth between deformation and recovery quickly without destroying their good sealing performance.

figure 5 How to use O-ring seals


What are the sizes of sealing O-rings?

Size according to your needs, refer to International Standard 3601-1 size code.

What is the difference between static and dynamic O-Rings?

Static O-Rings are in a relatively static surface environment, while Dynamic O-Rings are in a relatively moving environment. Dynamic O-Rings are made of materials that are more abrasion resistant and resilient than static O-Rings.

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