Different Types of O-Rings

Posted on November 11, 2020 Jerold Perkins Aviation

O-rings are found throughout a broad range of manufacturing and industrial facilities and machines. Their versatility and array of applications mean there are many different O-ring materials to choose from. This blog will explain O-rings and provide some information to help you decide what material of O-ring is best suited to your particular situation.

O-rings are among the most important features in any pressurized system. Though they are incredibly simple in nature, O-rings have a critical and complex function in modern machinery. O-rings are critical in creating a durable seal when compressed by two parts. The seal is placed in an area called the gland, where it has to withstand high levels of pressure. Because O-rings are so prevalent, they exist in many different types and materials. The most common materials used to manufacture O-rings are Buna-N (nitrile), Viton, silicone, Neoprene, PTFE, ethylene propylene, and polyurethane.

1. Buna-N (Nitrile O-rings)
Buna-N, or nitrile O-rings, are the most common general-purpose seal on the market today. It can withstand abrasive activity in addition to being tear-resistant. With a temperature range from -54 to 149°C, it is suitable for use in hydraulic fluids, petroleum, and water. Despite this, they are not recommended for use with halogenated hydrocarbons, nitro hydrocarbons, phosphate ester, ketones, or automotive brake fluid. This material is favored in applications that have limited resistance and temperature interaction.

2. Viton O-rings
Viton is considered somewhat of an all-in-one material. It has the capacity to handle a broad scope of applications, particularly those involving steady movement. The material is designed for use with acids, petroleum, silicone fluid, and even some halogenated hydrocarbons. However, Viton O-ring is not ideal for use in hot esters, hydrofluoric acid, amines, esters that have a low molecular weight, or Skydrol. Despite this, it is still a very versatile O-ring that can be used in many appliance, automatic, and chemical processes.

3. Silicone O-rings
Silicone is popular for use in petroleum, steam, and water applications. In some cases, silicone O-rings are even used in high temperature fuel injection ports. They are able to withstand many different temperatures, depending on the amount of exposure. Despite this, silicone O-rings exhibit relatively low tensile strength, abrasion strength, and tear resistance. Because of these factors, silicone O-rings are recommended for use in static machinery.

4. Neoprine O-rings
Neoprene is another type of general-purpose elastomer. It is known to be resistant to factors such as weather (oxygen, UV, and ozone) and petroleum. This makes Neoprene ideal for use in applications where other materials parts would not perform. Neoprene is resistant to flex cracking, has good abrasion resistance, and a similar operational temperature to nitrile. It is commonly found in refrigeration and air conditioning units.

5. PTFE O-rings
PTFE, or Polytetrafluoroethylene, is a versatile O-ring material. Its most valued features are its low absorption, chemical inertness, non-permeability, abrasion resistance, and corrosion resistance. PTFE can also withstand temperatures ranging from -73 to 260°C. Because it is a rigid material, PTFE is best suited for static applications. O-rings of this material are found in products such as paint guns, automotive steering devices, and more.

6. Ethylene Propylene O-rings
Ethylene Propylene (EPR) is ideal for use in O-rings that will be exposed to corrosive fluids such as Skydrol, alcohols, brake fluids, silicone oils, water, and steam. EPR is well-known for its compression and heat resistance. These EPR O-rings are highly popular in hydraulic pumps as well as the aerospace sector. The final material, polyurethane, is noted for its all-around toughness and resistance to extrusion and abrasion. Despite this, it is not recommended for applications that call for heat resistance and positive compression. It is best suited for use between -54 and 100°C and is commonly used in valves, cylinders, firearms, and pneumatic tools.

The importance of O-rings cannot be overstated. As such, when purchasing O-rings, be sure you are getting them from a trusted source like Aerospace Exchange.

Aerospace Exchange provides all types of O-rings and much more for a wide range of military and civilian applications. Owned and operated by ASAP Semiconductor, we can help you find all types of unique parts for the aerospace, civil aviation, and defense industries. Our dedicated account managers are standing by and ready to help you find all the parts and equipment you need, 24/7-365. For a quick and competitive quote, email us at sales@aerospaceexchange.com or call us at +1-714-705-4780.

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