28/07/2022
Comparison of PTFE Spring Energized Seals Between Oring and U-ring
1. Components
O-ring
Commonly used rubber are nitrile rubber, fluorine rubber, silicone rubber and ethylene propylene rubber, etc.
U-ring
It is generally polyurethane, and a few are harder rubber
PTFE Spring Energized Seals
The body of the seal is generally filled PTFE, the matrix is PTFE, the filler is carbon fiber, copper powder, molybdenum disulfide, etc., and the spring is usually composed of various corrosion-resistant stainless steels and alloy spring.
2. Storage life
O-ring
Nitrile rubber, etc. are generally 2-10 years, fluorine rubber, silicone rubber 5-20 years
U-ring
Usually 5-10 years
PTFE Spring Energized Seals
Theoretically unlimited
3. Working medium compatibility
O-ring seal
The medium of O-ring seals is greatly depending on the material. There is no one that can hold all of them. For example, nitrile rubber is resistant to non-polar mineral oil, but it is poor for polar mineral oil, water, acid and alkali, etc.
U-ring
Resistant to mineral oil resistant hydraulic oil, not resistant to water and water liquids.
PTFE Spring Energized Seals
PTFE is resistant to almost all media, including strong acid and alkali, organic solvents, various oils, inorganic salts and organic salt solutions.
Stainless steel 304, 316, 718, etc. have strong corrosion resistance, and can be used in a variety of working media, such as various types of grease, water, etc.
4. Friction and wear
O-ring
The dry friction coefficient between rubber and steel is about 0.6-0.8, and the friction coefficient is between 0.3-0.5 when lubricated.
U-ring
Generally, the friction coefficient is slightly smaller than rubber under the same working conditions. The dry friction coefficient is between 0.3 and 0.5. When there is lubrication, the friction coefficient is between 0.2 and 0.4.
PTFE Spring Energized Seals
The dry friction between the filled PTFE and the metal material is about 0.15. When there is lubrication, the friction coefficient is between 0.01 and 0.05. Because the friction coefficient is quite different, the friction resistance and friction loss are also greatly different.
5. Physical aging, working creep
O-ring
In the process of storage and use, rubber is affected by various conditions of natural and artificial environment, and its performance and appearance deteriorate with time. Rubber products are often damaged by heat, oxygen and ozone in the air, sunlight, wind, rain, snow, moisture, and various mechanical stress or chemical solvent erosion during use, so that the chemical structure of rubber is damaged, becoming soft or hard and brittle. Crack, rough surface, decline in mechanical properties, and gradually lose use value over time.
When the O-ring is working, it will be subjected to a certain stress. Under the action of the stress, the shape of the O-ring will be permanently deformed, thereby partially or completely losing its working ability.
U-ring
Under the influence of heat, light, oxygen, water, etc., the mechanical properties gradually decrease. Under the action of stress, the polyurethane U-ring will deform to a certain extent, but usually the permanent deformation is small and generally does not affect the work.
PTFE Spring Energized Seals
Because the material itself is resistant to various solvents, temperatures, oxidants, etc., material deterioration and deterioration will not occur during storage and work.
The main component of the seal body is polytetrafluoroethylene, which may creep under the action of pressure, but because the sealing lip is mainly provided with the deformation restoring force by the spring, so it‘s not likely creep under the action of the working pressure and lose its working ability.
