Are you looking to keep your machinery free from unwanted leakages but aren’t sure which rotary shaft seal is right for your needs? This guide will provide you with everything you need to know to select the right oil seal for your application.
Oil seals, also known as rotary shaft seals, fluid seals, or grease seals, play an important role in closing gaps between moving and stationary elements of mechanical equipment. By preventing lubricants from escaping, they protect key components of machinery from being damaged by leaks of various fluids. Everything from car engines to assembly machines uses these oil seals to remain free from harmful interactions that can cause serious and expensive damage to critical parts.
There are a wide range of oil seals to select from for any number of uses, so this guide will break down the most common seals to help you choose the right one for whatever piece of machinery you are working on.
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.
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.
Oil seals serve to close the gaps between stationary and moving components in machinery, preventing the escape of lubricants and the ingress of contaminants. These seals are crucial in maintaining the efficiency and longevity of equipment by protecting sensitive internal components from harmful interactions. Common applications include automotive engines, industrial equipment, and agricultural machinery.
The manufacturing process of oil seals involves several steps, ensuring they meet the required specifications for various applications.
Rotary shaft seals, also known as radial shaft seals, are designed to seal the interface between a rotating shaft and a stationary housing. They are commonly used in automotive engines and industrial machinery.
Mechanical face seals, or duo-cone seals, are used in heavy-duty applications such as construction and mining equipment. They consist of two precision-machined metal faces that form a dynamic seal.
Water pump seals are specifically designed for water pump applications. They consist of stationary and rotating elements that create a watertight barrier.
Gland packings are made from braided or twisted fibers such as PTFE, graphite, or aramid. They are used in high-temperature, high-pressure, and corrosive environments.
| Type | Application Area |
|---|---|
| Rotary Shaft Seals | Automotive, Industrial Machinery |
| Mechanical Face Seals | Mining, Construction Equipment |
| Water Pump Seals | Automotive Engines, Industrial Cooling Systems |
| Gland Packings | Pumps, Valves, High-Pressure Systems |
Different materials are used to manufacture oil seals, each suited for specific operational conditions. The choice of material depends on factors like temperature, pressure, and chemical exposure.
Nitrile is known for its excellent resistance to oils and fuels, making it ideal for automotive and industrial applications.
Viton offers high resistance to chemicals and extreme temperatures, making it suitable for aerospace and chemical processing industries.
Polyacrylate seals are used in automotive and transmission applications due to their resistance to oil, fuel, and environmental elements.
Silicone seals provide high thermal resistance and flexibility, used in food processing and medical devices.
PTFE seals are known for their exceptional chemical resistance and low friction, suitable for pharmaceutical and chemical industries.
| Material | Properties | Applications |
|---|---|---|
| Nitrile | Oil/Fuel resistance, cost-effective | Automotive, Industrial Machinery |
| Viton | Chemical/Temperature resistance | Aerospace, Chemical Processing |
| Polyacrylate | Oil/Fuel/Environmental resistance | Automotive, Transmissions |
| Silicone | High Thermal resistance, flexible | Food Processing, Medical Devices |
| PTFE | Chemical resistance, low friction | Pharmaceutical, Chemical Industries |
Choosing the right oil seal involves considering several key factors:
Oil seals are designed for specific pressure ranges. Selecting a seal that can handle the operating pressure of your application is crucial.
Consider the temperature range within which the oil seal will operate. Materials like PTFE and Viton can handle extreme temperatures.
The speed at which the shaft rotates affects the wear and performance of the oil seal. High-speed applications require seals with high lubricity and wear resistance.
Ensure the oil seal material is compatible with the fluids it will encounter, such as oils, fuels, or chemicals.
Oil seals perform best when properly lubricated. In cases of sparse lubrication, materials like PTFE or leather may be advantageous.
| Criteria | Considerations |
|---|---|
| Pressure | Operating pressure range |
| Temperature | Operating temperature range |
| Shaft Speed | Speed of the rotating shaft |
| Fluid Type | Compatibility with oils, fuels, chemicals |
| Lubrication | Amount and type of lubrication |
Oil seals can be identified by their design, size, and material. Common designs include single and double lip seals.
Accurate measurement is crucial for selecting the correct oil seal. Measurements should include the inner diameter (ID), outer diameter (OD), and width (W).
| Measurement | Description |
|---|---|
| Inner Diameter (ID) | Diameter of the shaft the seal fits around |
| Outer Diameter (OD) | Diameter of the seal’s outer edge |
| Width (W) | Thickness of the seal |
Fully covered in rubber, these seals offer excellent resistance to thermal cycling and chemicals.
These economical seals have an exposed metal side, providing a closer fit between the seal and housing.
With an additional inner case, these seals offer greater structural rigidity for heavy-duty applications.
Similar to Type A, these seals include a corrosion-protected metal case and stainless-steel spring, suitable for a range of fuels and chemicals.
| Design Type | Description | Applications |
|---|---|---|
| Type A | Rubber covered, thermal/chemical resistant | General industrial, automotive |
| Type B | Metal outer diameter, economical | Automotive, light industrial |
| Type C | Reinforced metal insert, high rigidity | Heavy-duty industrial, construction |
| Type F | Stainless steel garter spring, corrosion resistant | Chemical processing, marine applications |
Here are some of the top oil seal manufacturers, known for their high-quality products and innovation:
