1、 O-rings overview O-rings are rubber sealing rings with circular section. Because their section is O-shaped, they are called O-rings, also known as O-rings. Its material is mainly butyl rubber or fluororubber. O-ring is the most widely used seal in hydraulic and pneumatic transmission system. It is mainly used for static seal and reciprocating seal. The service speed range is generally 0.005 ~ 0.3m/s. When used for rotary motion sealing, it is limited to low-speed rotary sealing device. Such as the distribution valve dynamic sealing mechanism of the central swivel of the hydraulic excavator. Generally, O-rings are rarely used in rotary motion sealing devices.

The O-ring is generally installed in the groove with rectangular section on the outer circle or inner circle to seal. Compared with other types of sealing rings, the O-ring has the following advantages:

1) Compact structure, easy assembly and disassembly;

2) Both static and dynamic seals can be used;

3) The dynamic friction resistance is relatively small;

4) The use of a single O-ring can seal in both directions;

5) The price is low.

2、 Marking method of O-ring specification: inner diameter Ф i  ×  Wire diameter D, for example: O-ring 20 * 2.4, Ⅱ - 2, in gb1235-76, 20 represents that the inner diameter of the large ring is 20mm, 2.4 represents that the cross-section diameter of the rubber ring is 2.4mm, Ⅱ - 2 represents the type of rubber used, gb1235 represents the standard number, and 76 represents the publication date of the standard.

3、 Application of O-ring O-ring is mainly used for static seal and reciprocating seal. When used for rotary motion sealing, it is limited to low-speed rotary sealing device. The O-ring is generally installed in the groove with rectangular section on the outer circle or inner circle to seal. O-ring still plays a good sealing and damping role in the environment of oil resistance, acid-base, wear and chemical erosion. Various types of sealing elements are widely used in machine tools, ships, automobiles, aerospace equipment, metallurgical machinery, chemical machinery, engineering machinery, construction machinery, mining machinery, petroleum machinery, plastic machinery, agricultural machinery and various instruments and meters. Compared with other sealing elements, O-ring has a wide range of advantages: - it is suitable for a variety of sealing forms: static seal and dynamic seal. It is suitable for various materials. The size and groove have been standardized and have strong interchangeability - it is suitable for a variety of motion modes: rotary motion, shaft re motion or combined motion (such as rotary reciprocating combined motion) --It is suitable for a variety of different sealing media: oil, water, gas, chemical media or other mixed media. Through the selection of appropriate rubber materials and appropriate formula design, it can effectively seal oil, water, air, gas and various chemical media. The temperature range is wide (- 60 ℃ ~ + 220 ℃), and the pressure can reach 1500kg / cm2 (used together with the reinforcing ring)-- The design is simple, the cross-section structure of O-ring is extremely simple, and has self sealing effect and reliable sealing performance-- It is easy to install. Because the structure of the O-ring itself and the installation part are extremely simple and standardized, it is very easy to install and replace-- Low cost - there are many kinds of materials, which can be selected according to different fluids: nitrile rubber (NRb), fluororubber (FKM), silicone rubber (VMQ), ethylene propylene rubber (EPDM), chloroprene rubber (CR), butyl rubber (BU), polytetrafluoroethylene (PTFE), natural rubber (NR), etc