The key factor for rubber O-rings is the application te […]
The key factor for rubber O-rings is the application temperature, and high temperatures will accelerate the aging of the rubber material. The higher the operating temperature, the greater the permanent deformation of the O-ring shrinkage. When the permanent deformation exceeds 40%, the O-ring loses its seal, resulting in leakage. Due to shrinkage and deformation, the initial stress values formed in the O-ring rubber data will gradually land and subside with the aerodynamic process of the O-ring and the effects of temperature landing.
The original shrinkage of O-rings operating at sub-zero temperatures may decrease or subside entirely due to the sharp temperature landing. O Generally, when using a sealing ring, try to choose an O ring with a large cross-section. In the same case, the volume of the O type sealing ring squeezed into the gap should be lower than its maximum value. The silicone sealing ring is made of open porous material, which can absorb various substances and is a good moisture-proof agent, absorbent and catalyst carrier. The adsorption of silica gel is usually physical adsorption, which can be regenerated and reused. Add acid to alkali metal silicate (such as sodium silicate) solution to acidify it, and then pour a certain amount of electrolyte for mixing, that is, to produce silicate suspicious glue; or add acid to strong sodium silicate solution Or ammonium salts can also produce silicate-like gums. In this case at -50~-60℃, the rubber material that is not resistant to low temperature will completely lose the initial stress; even for the rubber material that is resistant to low temperature, the initial stress will not exceed 25% of the initial stress at 20℃. This is because the original tightening of the O-ring depends on the expansion coefficient. Therefore, when choosing the original tightening amount, it must be ensured that there is still sufficient sealing capacity after the stress landing due to temperature landing during the stress landing process. For O-rings working at subzero temperatures, special attention should be paid to the recovery index and deformation index of the rubber material.
Generally speaking, in the design, try to ensure that the O-ring has a suitable working temperature, or use high-resistance and low-temperature O-ring materials to improve the service life. Silica gel products with silica gel as the main raw material are called silica gel products. Silica gel is a porous, porous substance of varying sizes made from silicic acid dubious glue. It is a good moisture-proof agent with open porous material, which can adsorb a variety of substances. Absorbent and catalyst carrier.