How to choose the right O-type silicone seal? 1. For the working medium and working conditions, when using the O-type silicone sealing ring material, the compatibility with the working medium must first be understood. The sealing pressure must also fully consider working conditions such as temperature, continuous working time, and working cycle. If used in rotating places, heating due to frictional heat must be considered. Different sealing materials have different physical and chemical properties. 2. Types of sealing forms, sealing forms can be divided into static seals and dynamic seals; according to the purpose of sealing, they can be divided into hole seals, axial seals and rotary shaft seals; according to their installation methods, they can be divided into axial installation and radial installation . In axial installation, for axial sealing, the error between the inner diameter of the O-ring and the sealing diameter d2 should be as small as possible; for hole sealing, the inner diameter should be equal to or slightly lower than the diameter d1 of the pipe groove. 3.Other factors that affect the sealing performance. 3.1. Hardness: O The hardness of the silicone sealing ring material is the main indicator for evaluating the sealing characteristics. The hardness of the O-ring rubber seal depends on the compression amount of the O-ring and the large allowable extrusion gap of the pipe groove. Since the nitrile seal of Shore A70 can meet most of the conditions of use, if the sealing material is not unique, the Shore A nitrile rubber seals
70 is generally provided. 3.2. Extrusion gap: system pressure. The cross-sectional diameter of the O-ring is related to the hardness of the material. Generally speaking, the larger the working pressure, the larger the extrusion gap and the lower the gmax value. If the gap g exceeds the allowable range, it will cause the O-type silicone seal to be squeezed or even destroyed. 3.3. Compression deformation: avoid plastic deformation under pressure. O In the static seal, the maximum compression allowed by the type silicone sealing ring is about 30%, and in the dynamic seal it is about 20%. 3.4. Pre-compression amount: In order to ensure the tightness of the O-type rubber seals sealing ring pipe groove, the initial compression amount should be reserved. Compared with the pre-compression of the section diameter, it is usually about 15%~30% in static sealing and about 9%~25% in dynamic sealing. 3.5. Stretch and shrink: seal the hole, the O-type silicone sealing ring is in a stretched state, the maximum allowable stretch is 6%, and the shaft is sealed, the O-type silicone sealing ring shrinks along the circumference direction, and the maximum allowable circumferential The long compression is 3%. 4. O silicone sealing ring is used as a rotary shaft sealing ring O silicone sealing ring can also be used for low-speed rotary motion and rotary shaft sealing, and the operating cycle is short. When the peripheral speed is less than 0. When the temperature is .5m/s, the selection of the O silicone sealing ring can be based on the normal sealing ring; when the peripheral speed exceeds 0; after heating at .5m/s, the shrinkage of the elongated rubber seals ring should be considered. Therefore, the above situation can be avoided by selecting the sealing ring with an inner diameter of about 2% of the diameter of the shaft it seals. After the sealing ring is installed in the groove, the sealing ring is axially reduced, and the O-ring silicone sealing ring produces a small amount of ripples in the groove, thereby optimizing the wetting standard.
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