Fluctuations in temperature and indeed heat is a significant factor across many applications that make use of o rings.
However, what is well known is how destructive heat can be when it comes to compound deterioration.
You are making choosing the ideal o ring suitable to withstand those high temperatures, essential.
Because of this, there are several factors that need to be taken into consideration.
In this post, we take a look at some of the most popular materials suitable for those high-temperature and chemical applications, what they are best used for and what applications they should avoid.
Most commonly found o ring materials and their suitability to specific applications
Viton, or FKM, is primarily used for automotive oils, fuels, and gases, due to its high level of resistance to these substances at extreme temperatures.
Viton ultimately does not allow liquids such as mineral oils, hydraulic fluids (non-flammable), grease and silicone oil to pass through the seals. Plus, it is extremely compatible with several hydrocarbons.
However, and important to note, we would not recommend the use of Viton material seals with liquids such as brake fluid, ammonia solvents, super-heated steam, and strong acids.
The material ACM, on the other hand, can resist gearbox oils, and transmission fluid. And the difference between ACM and FKM is that ACM can work at a lower temperature in comparison to Viton (150 degrees for 200 degrees, comparatively).
Nitrile or HNBR is the most recommended sealing product material for sealing that needs a strong abrasion compound. Ideal for oils, fuels, gases, hydraulic fluids, and more.
Please note: Nitrile does have limited resistance to brake fluids, and we don’t recommend this as a suitable material to withstand chlorinated hydrocarbons, strong acids, and polar solvents.
A material that can withstand temperatures of 232 degrees and is used in a range of automotive sealing is that of AFLAS. For all compression is affected here, this material is still more than suitable with all makes of automotive brake fluids, engine coolants, motor oils, gear lubricants, power steering fluids, and more.
However, AFLAS will not suitable for ketones, aromatic fluids, or chlorinated hydrocarbons.
Silicone or VMQ is a widely used o ring material due to its resistance to high temperatures. It is mainly used for products that are highly exposed to ozone, Ultra Violets, and weathering. Silicone is not, however, suitable for hot water, chemical, or dynamic applications.
Those universal compounds that offer both temperature and chemical resistance are both FFKM, perfluoro elastomers, and Teflon, PTFE. PTFE is a tough, robust, and inflexible Thermoplast, while FFKM is classified as a thermoset elastomer.
Unfortunately, PTFE material o rings are easily dented due to their hard material, so hence do suffer from high compression sets.
However, following in the footsteps of PTFE o rings is that of FEP o rings. A seal that has a chemical and heat resistance similar to a PTFE seal. However, an FEP is much more flexible. A practical and effective solution for static applications such as pumps.
FFKM is available through a variety of brands and can be provided in a variety of different material grades to suit a variety of different applications.
However, the price can be everything
Cost plays a vital role in the selection of an o ring, as well as the factors based on the materials we’ve outlined above.
It’s important to be aware that there is a price difference between the different compounds of o rings, as well as sizes and grades.
Being aware of this and the different materials available and what they are most suitable for will help you make the most informed decision, suitable for your application.
Specialist Sealing Products are one of the leading suppliers of o rings throughout the UK. Based in Leeds, we work with many businesses, with a number of applications, all looking for the best sealing products around.
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