Notes for maintenance users When purchasing seals for maintenance, most users will buy according to the size and color of the sample, which will only increase the difficulty of purchasing, and may not be able to select the right product. The following procedures are recommended to improve the accuracy of purchasing seals:
1. Movement direction - first determine the movement direction of the location of the seal, such as reciprocating, rotating, spiral or fixed.
2. Sealing focus - such as determining the active point is the tie rod seal on the inner diameter or the active point is the piston seal on the outer diameter, etc.
3. Temperature class - Refer to the original machine operating instructions or evaluate the working temperature according to the actual working environment to determine the required materials. A description of temperature ratings can be found in the Production User Notes below.
4. Pressure level - Check the relevant data from the original mechanical operating instructions, or infer the working pressure level by observing the hardness and structure of the original seal. For the description of the pressure level, please refer to the following precautions for production users.
5. Size - Most users will buy according to the old samples that have been used, but the original size of the seal will be greatly affected by factors such as temperature, pressure and wear after a period of use, and the selection can only be used as a reference. , a better method is to measure the size of the metal groove where the seal is located, and the accuracy will be higher.
Production and user precautions The damage of general seals is also almost the working requirements for seals:
1. Hardening (aging) - One of the reasons for the leakage of seals is that the material itself is hardened by the influence of temperature. When the hardness is too high, the seals cannot fill the gaps with the mating parts, and leakage will occur.
2. Wear - The wear of seals involves the surface finish, movement speed and transmission media of the matching parts, etc. Different sealing materials adapt to different movement speeds.
3. Extrusion - When the seal is subjected to excessive pressure, it will be squeezed out into the metal gap, damaging the seal and causing leakage. This situation involves the hardness of the seal itself and whether the metal gap is too large. , Improper handling in processing or installation, extrusion damage will occur.
4. Corrosion - It manifests itself in softening or even dissolving of the seal due to the intrusion of the seal by the media and an error in material selection. Take special care if the media contains water or solvents.
5. General seals can be classified as follows according to temperature, speed, pressure and material (for reference only):
Temperature Class Applicable Material Speed Applicable Material Pressure Class Applicable Material
110℃ Nitrile/Polyurethane 0.5 M/S Nitrile 200kg/cm2 Compounding hardness and design
200℃ Viton 0.6 M/S Polyurethane 400kg/cm2
260℃ PTFE 14 M/S PTFE 700kg/cm2 with hardness and design
