Replacing a critical component can be difficult to get right, especially if you do not have the original machine specifications. Thankfully, there are a few ways to identify oil seals; from their design, size and material. As there are hundreds of different oil seals available on the market, this guide will cover the four most common design types. Typically available with either a single or double lip, in Nitrile or Viton Rubber Material.

Oil Seal Single Lip vs Double Lip

Firstly, the oil seals covered in this guide classify the single lip as the inner diameter at the bottom of the component. The single lip is vital to the function of the seal by containing the oil, grease or lubricant. The only difference between a single and double lip is the additional rubber lip on the top of the oil seal which helps prevent dust or dirt from coming close to the shaft. Identifying the oil seal lip can be misinterpreted with a visual inspection alone. For or this reason, you should press along the inner diameter at the top of the seal, if you feel a ridge with a slight movement or give it is highly likely you have a double lipped oil seal.

Industry retailers use unique codes to identify oil seals worldwide. The most common lip style designations are 21 (single lip) and 23 (double lip), please read our Oil Seal Cross Reference Guide for more detailed information.

Identify Oil Seal Design

1. Type A - Rubber Covered Lip Seals

Fully covered outer diameter for excellent sealing. This oil seal is fully enclosed in a rubber material and is the most widely used type of oil seal. Great resistance to thermal cycling, temperatures and different chemical resistance.

2. Type B - Metal Outer Diameter Oil Seals

Economic metal outer diameter for standard applications. This is an economical oil seal where the metal is exposed on one side and offers a closer fitting between the oil seal and housing or bore. Due to this, it has limited use with sealing thin liquids or gases.

3. Type C - Reinforced Metal Insert Oil Seals

The same design as type B with an additional inner case for greater structural rigidity. This type of oil seal is typically used in heavy-duty engineering machinery or large diameter sized seals

4. Type F - Stainless Steel Garter Spring

The same design as type A with corrosion protected metal case and stainless-steel garter spring. Suitable for use with a wide range of fuels and chemicals.

Identify Oil Seal Material

Nitrile or NBR is black in colour, whereas, Viton or FKM is usually a brownish colour. To understand the main comparisons between the two compounds read our Nitrile vs. Viton article.

How to Measure Oil Seals

Finally, Polymax part codes follow the same pattern as our O-rings - inner diameter, outer diameter and height. This is different from the industry-standard convention, whereby imperial oil seals follow - outer diameter, inner diameter and height.

We hope the information in this article helps you identify the correct oil seal for your application. If you have any queries feel free to call one of our sales engineers on 01420 482862. Polymax stock over 6,000 oil seals available to buy online, browse our oil seal selection today.

Rubber seals are used in numerous industries to prevent the unwanted leakage of liquids and gases in various components such as pumps, valves, pipe fittings, and vacuum seals, to name only a few. However, all seals are not created equally. Rubber seal design consists of several elements to ensure that the seal delivers optimal performance in the given environment.

One of the most common types of industrial rubber seals, the O-ring, relies on mechanical compressive deformation to act as a barrier between mating surfaces, thus restricting the flow of fluid in predetermined areas. Several factors must, therefore, be taken into account in O-ring seal design to sustain the compressive force and maintain an effective seal.

Key Design Considerations

Rubber seals are available in a large number of material compositions, each with its own set of advantages and limitations. The selection of the appropriate material involves the consideration of specific factors including:

Dimensional Requirements

To provide a proper seal, the O-ring needs to be compressed between the mating surfaces. The deformation caused by this compression is what prevents fluid leakage. To achieve the proper compressive force and deformation, the cross section of the O-ring needs to be sufficiently larger than the gland depth.

As the two mating surfaces press together, the O-ring seal compresses axially and exerts an equal and opposite force at the top and bottom ends of the seal. If the O-ring is too small, the seal may not compress when the surface come together. On the other hand, an O-ring that is too large will over pack the gland and disrupt the connection between the mating surfaces.

Friction

Friction considerations are essential in dynamic applications – in situations that involve relative movement between the mating surfaces.

In reciprocating applications, these movements can generate frictional forces which may cause failure due to abrasion or extrusion and successive nibbling of the seal. In rotary applications, friction may generate excessive heat and seal expansion due to the Joule effect. In both of these applications, proper groove design, along with appropriate lubrication and speed of operation can help to avoid these issues. Silicone and related materials such as Fluorosilicone, liquid silicone rubber, and medical grade silicone are often avoided in dynamic applications due to their low abrasion/tear resistance.

Temperature

Long-term exposure to excessive heat can cause inappropriate rubber seals materials to deteriorate physically or chemically over time. Excessively high temperatures can cause specific materials to swell and harden, resulting in permanent deformation. Conversely, overly cold temperatures may cause material shrinkage and result in leakage due to loss of seal contact, or insufficient compressive force due to stiffening of the rubber compound.

Therefore, the appropriate seal material should be selected to withstand the expected temperature ranges of the environment. The length of exposure should also be considered. For example, would the temperatures be sustained in short intervals or at sustained levels?

Pressure

Differential pressures tend to push rubber seals (o-rings) to the low-pressure side of the gland causing it to distort against the gland wall. This action blocks the diametrical gap between the mating surfaces and results in the formation of a positive seal. Excessively high pressures can cause softer O-ring materials to extrude into the diametrical gap resulting in permanent seal failure and subsequent leakage. To avoid this situation, seal materials that operate optimally within the expected temperature range should be selected.

Chemical Compatibility

One of the most critical considerations for rubber seals design and material selection is determining the material’s resistance to exposure to specific chemicals. Some fluids can react negatively with certain materials while having little to no effect on another. For example, Nitrile is highly resistant to petroleum-based oils and fuels, while the use of Butyl is avoided in applications with exposure to petroleum and other hydrocarbon-based solvents due to its poor resistance.

Remember to keep dimensional requirements, friction, temperature, pressure, and chemical compatibility in mind when it comes to customizing a rubber seal solution for your application.

For more information about custom seal designs or to see which seal might be the best fit for your application, contact Gallagher Fluid Seals.

The original article can be found on Precision Associates website, and was written in January 2019.

Top 8 Installation Tips for Oil Seals

Rubber oil seals play a significant role in preventing contamination and leakage in various applications, from automotive engines to industrial machinery. Although widely used seals, many users fail to get the results as expected mainly due to improper installation in applications. Understanding what rubber oil seals are and how to install them correctly is essential for ensuring the efficient and reliable operation of these systems. Would you like to get a clear clarity about oil seals and how to install them correctly in your applications? If yes, continue reading this post.

What are Rubber Oil Seals?

Rubber oil seals, also known as oil seals, are popularly used components in various industrial applications especially to prevent the leakage of fluids, such as oils or lubricants, from machinery or equipment. Made to fit tightly around rotating or moving shafts, these industrial oil seals, efficaciously create a barrier between the inner workings of the machine and the external environment.


As they are made from synthetic rubber materials, such as nitrile rubber, these seals offer excellent sealing properties, along with resistance to oil and other fluids. The rubber material is molded into a ring shape, often with a metal casing or reinforcement to provide structural support and ensure durability.

Steps to Install Rubber Oil Seals Properly

Following the steps below leads to a proper installation of industrial rubber seals when used in your applications.

1. Prepare the Surface: Take out the oil seals from their packaging only just before installation. Before installing the rubber oil seal, make sure the surface where it will be installed is clean and free of any debris or contaminants. Wipe the surface with a clean cloth or use a solvent if necessary to remove any grease or oil.
2. Inspect the Rubber Oil Seal: Before blindly installing the seal, have a thorough check and inspect the rubber oil seal for any damage or defects. Ensure to use a seal of the correct size and type for your application.
3. Apply lubrication: Apply a thin layer of lubricant to the industrial oil seal. This will help the seal slide into place smoothly and prevent any damage during installation.
4. Position the seal: Now carefully position the rubber oil seal on the designated area. Ensure that the seal is aligned correctly and evenly with the surface. Avoid stretching or distorting the seal during this step.
5. Use a seal installation tool: To securely install the seal, it is advisable to use a seal installation tool. This tool is specifically designed to prevent any damage to the seal and ensure a proper fit. If you need advice on the right tool, get in touch with the oil seal manufacturer.
6. Apply consistent pressure: When installing the seal, ensure to apply consistent and even pressure around its circumference. You can gradually push the seal into its housing with a gentle, tapping motion. Applying excessive force can deform or damage the seal.
7. Check the seal: Once done with the installation, double-check that it is seated correctly and evenly. Ensure that the seal is flush with the surface and there are no gaps or misalignments.
8. Test for leaks: Testing the rubber oil seal for leaks is the last and crucial step. Apply appropriate fluid or pressure to the sealed area and carefully observe for any signs of leakage. You may make necessary adjustments or repairs to ensure proper sealing.

If you are still confused and have more doubts about rubber seals and their installation, get in touch with trusted oil seal manufacturers such as SSP Seals. With their expertise and experience, they can provide you with comprehensive information and guidance to ensure the successful use and installation of these seals.

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