Apr. 17, 2023
Available in a range of sizes, single lip seals are suitable for most applications.
Dual lip seals are typically used for difficult sealing applications requiring the separation of two fluids.
The chart below shows different design considerations for single and dual lip seals. To view our cross-reference chart, download the Oil Seals Brochure.
What is an oil seal?
Seals are essential to protecting the bearings of any rotating shaft assembly -They prevent contaminants such as dirt, dust and water, while also preserving the system’s lubricant.
Choosing the right oil seal
Oil seals come in many different types and materials depending on their application. Determining the material is vital to ensuring your equipment is operating at its best performance. For example, your equipment may need to run at higher temperature applications, such as an engine seal for a jet engine, you may need to choose a specific material for your oil seals to run properly. In this article, we will explore the most popular and utilized materials in the industry, as well as touch on some of the more unique options out there.
Oil seal materials
Nitrile
The first material that we are going to look at is Nitrile Buna- N 70 or NBR for short.
NBR is recommended for the majority of standard applications and is the most commonly used rubber (elastomer) material. This is because of Nitrile's compatibility with most environments as well as its relatively low cost. Generally nitrile is used for disposable non-latex gloves, footwear, automotive transmission belts, synthetic leather, hoses, o-rings, gaskets, oil seals, and more.
The temperature range of nitrile is −35° to 120 °C (−30° to 250 °F). Due to this wide range, NBR seals can be used for gas oil, silicone oil, animal/vegetable oils and fat, hydraulic liquid as well as hot and cold water. In addition, NBR is oil resistant and has an excellent abrasion resistance, so for any application that demands shock absorbers, NBR is a perfect choice to go with.
Some disadvantages of NBR are poor ozone, sunlight and weather resistance as well as limited high temperature and flame resistance. For higher temperature resistance, a much better material to use is Silicone.
Silicone
Silicone compounds or “VMQ” offers a wide range of traditional operating temperatures starting at -60°C to 200°C (-140°F to 392°F).
In addition to its excellent temperature resistance, it is also resistant to ozone, light, and weather conditions. Silicone can be typically found in the food and medical industry as well as in hydraulics and pneumatics. It is often the preferred material for o-rings, moulded parts and flat seals but is also commonly used for electric insulators due to the material’s translucency and flexibility.
Although extremely flexible, silicone does have some disadvantages. Many silicone compounds have poor tensile strength, tear resistance, and abrasion resistance. If you are looking for a material that offers a higher tensile strength, while still offering high temperature resistance, look no further than Viton®.
Viton®
Viton®, a trademarked name of The Chemours Company, is a specific brand of synthetic rubber commonly used in o-rings, oil seals, gaskets, chemical resistant gloves, and other molded products.
Due to having a higher density, Viton has the widest temperature range of -40°F to over 400°F (-40°C to over 240°C) making it a perfect choice for higher temperature applications. Viton® also has the largest range of chemical resistance, i.e., it is resistant to silicone oil and grease, mineral/vegetable oil and grease, aliphatic, aromatic, and chlorinated hydrocarbons, non-flammable hydraulic fuels as well methanol fuels, and more.
Although it does have a higher tensile strength and longer wear times than other materials, it is recommended to be used in dry-running applications sparingly or intermittently.
While Viton offers a superior temperature and chemical range than other materials, it can be more expensive than the others as well. Let’s take a look at an alternative that is easier on the wallet, Polyacrylate.
Polyacrylate is a great compromise between cost and quality. It has a high performing temperature and chemical range, but not to the extent of the range of Viton. The temperature ranges from 31°C to 148°C (-25°F to 300°F). Polyacrylate is primarily used in automotive transmissions and hoses but also found in shaft seals, gaskets and o-rings, due to offering a high resistance to hot oil and oxidation. While Polyacrylate is a great alternative to other high temperature resistant materials that are more expensive, it does have a poor water compatibility and cold flexibility. The best situation for Polyacrylate is an environment where heat and oil resistance but cost is the major issue. And while these 4 different materials cover a wide range of applications, there are even more materials out there designed for very specific niches in mind.
Summary
If you are looking for the highest temperature resistant oil seals, Perfluoelastomer can go up to 600°F. If you are more concerned for low temperature, Chloroprene can go all the way down to 40°F, which is why it is used most commonly for refrigeration. And if FDA applications or medical devices are your primary concern, Butyl , the all petroleum compound, will be your best choice. As you can see, when choosing the right material to work with, you must analyze several other key components to help choose the right one.
Hopefully after reading this article, you have a better understanding of why choosing the right materials for oil seals is so important. Remember, if you have any questions about industrial oil seals and supplies, please contact us and we would be more than happy to help.
Products
Oil Seals
Description
Oil seals and grease seals have a flexible lip that rubs against a shaft or housing to prevent the leakage or ingress of fluids and dirt.
For proper installation, the seal lip should point towards the medium being contained. Some oil seals and grease seals have a spring to help keep the lip in contact with the shaft.
Oil and grease seals are used to retain or separate lubricants or fluids. These seals are primarily used for rotary applications only.
Types
The seal type for oil seals and grease seals can be oil seals or other types. An oil seal can also called flexible lip, radial lip, or rotary shaft seal. Common configurations include single lip, double lip, triple lip, and four or more lips.
Bearing Isolator
Bearing isolators are dynamic seals designed to protect bearings from outside contaminants. They are comprised of a rotor (rotating) and stator (stationary) member. Some bearing isolators are of labyrinth construction while others use O-rings or other positive seals.
Other types of oil seals and grease seals include:
Specifications
Sealing Orientation
The sealing orientation and direction is important to consider for oil seals and grease seals.
Piston seals are radial seals. The seal is fit onto a shaft with the sealing lip contacting the housing bore. V-rings are considered external lip seals.
An axial seal seals axially against a housing or machine component.
A symmetric seal is symmetrical and works equally well as a rod or a piston seal.
Rod seals, also referred to as shaft seals, are radial seals. The seal is press-fit into a housing bore with the sealing lip contacting the shaft.
An axial seal seals axially against a housing or machine component.
A symmetric seal is symmetrical and works equally well as a rod or a piston seal.
Dimensions
Service Limits
Lip Materials
SC
Low-pressure single lip with garter spring. Rubber covered OD to improve the OD sealing ability. Internal face of the steel case is not fully rubber covered.
KA-H
Non-pressure dual lip without garter spring provides protection from contaminants. Precision ground metal OD with an additional inner metal case for increased structural rigidity
SF
Low-pressure single lip with garter. Rubber covered OD to improve the OD sealing ability. Internal face of the steel case is fully rubber covered to prevent corrosion.
TF
Low-pressure dual lip with garter spring provides protection from contaminants. Rubber covered OD to improve the OD sealing ability. Internal face of the steel case is fully rubber covered to prevent corrosion.
VF
Non-pressure single lip without garter spring. Rubber covered OD to improve the OD sealing ability. Internal face of the steel case is fully rubber covered to prevent corrosion.
KF
Non-pressure dual lip without garter spring provides protection from contaminants. Rubber covered OD to improve the OD dealing ability. Internal face of the steel case is fully rubber covered to prevent corrosion.
SM-H
Low-pressure single lip with garter spring. Precision ground metal OD with a lead-in chamfer for ease of installation. Internal face of the steel case is fully rubber covered to prevent corrosion.
TM-H
Low-pressure dual lip with garter spring provides protection from contaminants. Precision ground metal OD with a lead-in chamfer for ease of installation. Internal face of the steel case is fully rubber covered to prevent corrosion.
VM-H
Non-pressure single lip without garter spring. Precision ground metal OD with a lead-in chamfer for ease of installation. Internal face of the steel case is fully rubber covered to prevent corrosion.
VB-H
Non-pressure single lip without garter spring. Precision ground metal OD with a lead-in chamfer for ease of installation.
VA-H
Non-pressure single lip without garter spring. Precision ground metal OD with an additional inner metal case for increased structural rigidity.
TC
Low-pressure dual lip with garter spring provides protection from contaminants. Rubber covered OD to improve the OD sealing ability. Internal face of the steel case is not fully rubber covered.
VC
Non-pressure single lip without garter spring. Rubber covered OD to improve the OD sealing ability.Internal face of the steel case is not fully rubber covered.
KC
Non-pressure dual lip without garter spring provides protection from contaminants. Rubber covered OD to improve the OD sealing ability.Internal face of the steel case is not fully rubber covered.
SB-H
Low-pressure single lip with garter spring. Precision ground metal OD with a lead-in chamfer for ease of installation.
TB-H
Low-pressure dual lip with garter spring protection from contaminants. Precision ground metal OD with a lead-in chamfer for ease of installation
KB-H
Non-pressure dual lip without garter spring provides protection from contaminants. Precision ground metal OD with a lead-in chamfer for ease of installation.
SA-H
Low-pressure single lip with garter spring. Precision ground metal OD with an additional inner metal case for increased structural rigidity
TA-H
Low-pressure dual lip with garter spring provides protection from contaminants. Precision ground metal OD with a lead-in chamfer for ease of installation.
KM-H
Non-pressure dual lip without garter springs provides protection from contaminants. Precision ground metal OD with a lead-in chamfer for ease of installation. Internal face of the steel case is fully rubber covered to prevent corrosion.
Many seal manufacturers use their own proprietary material. Consult with manufacturer for proprietary material specifications.
RELATED PRODUCTS
Are you interested in our products?
You are welcome to call us and we will get back to you within 24 hours
FOUNDED IN 1993
China SBT Oil Seal is an international company integrating design, research and development, production and processing.
No. 68, Hua'an Street, Renze District, Xingtai City, Hebei Province, China
+86 188 0309 4557
Won many honorary certificates through a number of patented inventions
