O-rings are a commonly used seal across a range of manufacturing and industrial industries. However, their versatility, array of applications, and materials they are made out of can make choosing the right O-ring material for your use difficult.
In order to give you a clear understanding of the options in front of you, we have compiled this helpful O-ring material guide – outlining the various advantages and disadvantages of O-ring material choices.
Why use O-rings?
O-rings are one of the most critical features found in an industrial pressure system. While they are simple in natural, these small and large seals serve an important and complex function in modern day machinery. These small elastomer, circular mountings are essential for a highly durable seal when two separate parts compress it. The area in which the seal is placed is industrially known as the gland. At various points, these seals have the capacity to withstand large levels of pressure.
A spectrum of materials may be used for O-ring fabrication (molding), including nitrile, silicone, neoprene, polyurethane, and other products that are similar in nature. Even micro-sized seals can be created using a precision molding process. O-rings can generally be customized for any size and material depending on the system and use case of the seal itself.
O-rings can be found in a variety of industrial uses and applications. The reason that they are so prevalent, is the fact that they are produced from an array of elastomers. This renders a particularly functional and durable end product.
As with all products, we know that too many choices can become confusing. In fact, do you really know what characteristics separates specific materials from another? Before you discuss your needs with an experienced O-ring adviser, which should be your first step for application guidance, read this detailed comparison of O-ring materials to discover more about various common elastomer O-ring qualities.
Buna-N (Nitrile) O-rings
Buna-N, also know as Nitrile O-rings are one of the most common general-purpose type of seal available on the market today. Not only can it hold up against abrasive activity, it is also tear-resistant. With a temperature scope between negative 54 and 149°C, Nitrile is suitable for use with hydraulic fluids, petroleum, and water. However, these O-rings are not recommend for use with halogenated hydrocarbons, nitro hydrocarbons, phosphate ester, ketones, or automotive brake fluid.
Nitrile weather and ozone resistance is unfailing, although overall strength can be improved with compounding techniques. This product is favorable for use in applications that have limited resistance and temperature interaction.
Viton
This O-ring can best be described as an all-in-one material. Viton has the capacity to handle a spectrum of applications, especially operations that involve steady movement. The material is well designed for use with acids, petroleum, silicone fluids, and even certain halogenated hydrocarbons.
However, for use cases in hot or esters hydrofluoric acid, amines, ethers that have a lower molecular weight, and Skydrol. Despite these use cases, Viton is a highly versatile O-ring material that finds its home a range of appliance, automatic, and chemical processes.
Silicone
This O-ring material is particularly favored for its use in petroleum, steam, and water applications. In some cases, Silicone O-rings are even discovered in fuel injection (high temperature) ports. These have been tested to withstand extreme low temperate in vary small increments of exposure. However, silicone also exhibits poor tensil strength, abrasion strength, and poor tear resistance. Therefore, the material is better crafted for static machinery.
Neoprene O-rings
This type of O-ring is another general-purpose type of elastomer. Neoprene is a unique material choice known to be resistant to weather (oxygen, UV, and ozone) and petroleum. This characteristic qualifies Neoprene for use in applications where other materials parts would not perform. Overall the product is resistant to flex cracking, along with good abrasion and resistance. Its operational temperature is shared with nitrile. It is commonly found in refrigeration and air conditioning units. Keep in mind that some people have reported mild allergic reactions to the use of neoprene.
PTFE
PTFE is a versatile O-ring material. Some of its most valued characteristics include its low absorption, chemical inertness, non-permeability, abrasion resistance, and corrosion resistance. This product can withstand a range of temperatures between negative 73 and 260°C. Because PTFE is hard to apply [rigid], it is best suited for static application types. PTFE O-rings are commonly found in products like paint guns and automotive steering devices, to name a few.
Ethylene Propylene
Contrary to Viton material, EPR O-rings work verifiably well with corrosive fluids such as Skydrol hydraulic, in addition to alcohols, brake fluids, silicone oils, water, and steam. This material is most well known for its compression resistance and positive heat handling. Compared to Nitrile, this material is the perfect choice for a variety of uses due to resistance to wear and tear. Ethylene propylene is a widely used material within hydraulic pumps and the aerospace sector.
Polyurethane O-rings
This last O-ring material is praised for being tough all-around, in addition to its extrusion and abrasion resistance. However, this material is not recommended for applications that require heat resistance and positive compression. Its standard temperature of operations is between negative 54 and 100°C. Polyurethane is most commonly used in valves, cylinders, firearms, pneumatic tool, fittings.
The importance of O-ring seals should never be underestimated. Although these parts can be small in the grand scheme of an application or machinery, they are essential to preserving your moving and non-moving parts. Even the smallest of seals can withstand high amounts of pressures. In fact, the Challenger space shuttle experienced a very huge disaster due to the importance of O-rings. The explosion of this spacecraft was attributed to O-ring cold temperature failure.
If you have questions about choosing the right O-ring for your application, don’t be afraid to reach out to your personal O-ring seal expert for help.