For many years, oil-tight joints have been achieved with either cork or NBR gaskets. Today though, as silicone is being used in an ever-growing list of applications, is it time to switch? Here’s a look.
Silicone Strengths
Characteristics of silicone that make it an excellent gasket material include:
- Wide temperature range (-60° to 480°F)
- Available in very soft grades (down to 10 Shore A)
- Good compressibility and compression set resistance
- Compatibility with an extensive catalog of chemicals
- Available in a range of colors and FDA-approved grades for food and medical uses
- Good ozone, UV and weathering resistance
Cork as a Gasket Material
Natural cork was one of the first gasket materials, and in some regards, still performs well. It compresses readily and resists water and many chemicals. Today, cork is often mixed with neoprene or nitrile rubber for better sealing behavior. A major limitation is a working temperature range of -22° to 212°F.
Properties of NBR for Gaskets
NBR, also known as nitrile and Buna-N, was one of the first synthetic rubbers. Like silicone, it has good compressibility and recovery. Its temperature range is -40° to 226°F.
NBR resists attack by a long list of chemicals, including lubricating and hydraulic oils. It is however, damaged by UV and ozone, so is best used indoors rather than out.
Can Silicone Replace NBR and Cork?
One of silicone’s few weaknesses as a gasket material is susceptibility to gasoline, lubricating oils, and anything else containing hydrocarbons. In addition, its resistance to hydraulic oil is only fair.
So, the answer is, to create oil-tight seals, stick with a traditional gasket material. NBR is almost always a good choice, providing it can handle the expected temperatures.
Ask Hennig About Oil-Resistant Gasket Material
Oil leaks are messy and potentially dangerous. The secret to oil-tight joints is to use the correct gasket material. While silicone is an excellent choice for many applications, it doesn’t hold up well to lubricating oils, so it’s better to stick with the traditional materials.
As always, for advice on any aspect of gaskets and seals, contact our experts on 1-800-747-7661 or via our website.
