The 4 most common mechanical seal types and variations

06 Aug.,2024

 

The 4 most common mechanical seal types and variations

Choosing the appropriate mechanical seal is crucial for ensuring optimal performance, reliability, and longevity of your equipment. Here&#;s a guide to help you select the right seal based on key factors:

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1. Seal Application Type

Identify the specific application and the type of equipment where the seal will be used. Different seals are designed for various applications such as pumps, compressors, mixers, and more. Ensure the seal type matches the equipment's requirements.

2. Seal Operating Conditions

Consider the operating conditions of your system, including:

  • Pressure: Determine the maximum and minimum pressures the seal will need to withstand. High-pressure applications often require more robust seals like parallel spring or wave spring seals.
  • Temperature: Identify the operating temperature range. High-temperature environments may necessitate seals designed for thermal stability, such as wave spring seals.
  • Fluid Type: Consider the type of fluid or gas being sealed. Some seals are better suited for aggressive chemicals, while others are ideal for water, oils, or hygienic applications.

3. Seal Material Compatibility

Select seal materials that are compatible with the fluid or gas being handled to ensure durability and performance. Common materials include:

  • Elastomers: Ideal for general-purpose applications involving water and oils.
  • PTFE (Polytetrafluoroethylene): Highly resistant to corrosive chemicals, suitable for harsh chemical environments.
  • Silicon Carbide and Ceramic: Provide excellent wear resistance and are often used in high-temperature applications.

4. Seal Design

Choose a seal design that fits the installation space and accommodates any misalignment or axial movement. Options include:

  • Conical Spring Seals: Simple and easy to install, suitable for moderate pressures and temperatures.
  • Elastomeric Bellows Seals: Flexible and clog-resistant, ideal for hygienic and general industrial applications.
  • Multiple Springs Seals: Provide uniform load and reliability for demanding applications.
  • Wave Spring Seals: Compact design for confined spaces and high-efficiency applications.

5. Seal Environmental Factors

Consider external factors such as:

  • Vibration and Movement: Ensure the seal can handle any mechanical vibrations or shaft movements.
  • Contamination Risk: Select seals that can prevent contamination in sensitive applications like food and pharmaceutical manufacturing.

Selecting the right mechanical seal involves understanding your application's specific needs, operating conditions, and material compatibility. By carefully considering these factors, you can ensure the optimal performance and longevity of your equipment. If you need further assistance, our team is here to help you choose the best seal for your requirements.

How to Measure and Identify Oil Seals

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.

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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 . Polymax stock over 6,000 oil seals available to buy online, browse our oil seal selection today.

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