How to Choose an O-Ring for Harsh Environments
Choosing the right O-ring material for harsh environments involves considering factors such as temperature range, chemical compatibility, and mechanical properties. Key considerations include the material's resistance to compression set, abrasion, and extreme temperatures. Each material has its unique pros and cons, and selection should be based on specific application requirements.
When designing seals for tough applications, an O-ring should be your first point of consideration. Selecting the appropriate O-ring for harsh environments will make or break your seal. It can be frustrating and difficult to find a well-designed O-ring made from the right material for your environment, but you can start by considering the primary factors that will impact your seal, including but not limited to:
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Once you determine these parameters, you can tackle the next hurdle: choosing your O-ring material.
Choosing Your O-Ring Material
Depending on your parameters and application, certain rubbers or plastics might be better suited for your needs. We have compiled a list of four common formulas best suited for a variety of applications and price points.
Perfluoroelastomers (FFKM)
Perfluoroelastomer (FFKM) was first developed in the 1960s. It is a fluorinated, carbon-based synthetic rubber known for its chemical resistance, heat resistance, and high-performance capabilities. FFKM is the typical choice for many applications. Although it can be on the expensive side, FFKM usually outlasts inferior alternatives, making it more cost effective in the long run.
Pros:
High temperature ratings, up to approximately 635°F (335°C), and lower temperatures, going down to -49°F (-45°C).
Nearly universal chemical compatibility.
Excellent gas and liquid permeation resistance.
Excellent weather ability and ozone resistance.
Self-extinguishing and non-flammable in air.
Low outgassing properties.
Good mechanical properties, improving sealing performance.
Suitable for explosive decompression, CIP (Clean in Place), SIP (Steam in Place), USP Class VI, and FDA.
Cons:
What applications is FFKM best suited for?
FFKM is best suited for high temperature applications where other materials would fail. It is commonly used in industries like oil and gas, medical and pharmaceutical applications, and semiconductors. Specific FFKM applications include:
FFKM is also suitable for semiconductor applications:
Chemical sprayers, injectors, and reactors
Connectors, controls, and filters
Petro-Chem equipment, sour gas
Ink handling & spraying equipment
Inorganic & Organic Acids & Alkine
Ketones, Esters, Ethers, Aldehydes
Etch, Strip, LPCVD, Litho/Track, ECP, Exhaust valves
Polytetrafluoroethylene (PTFE)
Polytetrafluoroethylene, also known as PTFE or Teflon, is a hard plastic with a high molecular weight of fluorine and carbon. Unlike FFKM, PTFE is inelastic and very rigid.
Pros:
Unaffected by all known acids, alkalis, and solvents allowing for maximum chemical resistance.
Low coefficient of friction, making it an excellent nonstick option.
Very wide temperature range, from -329°F (-200°C) to 482°F (250°C).
Chemically inert.
Self-cleaning.
Durable.
Non-flammable.
Good corrosion resistance.
High electrical resistance.
Cons:
Additional resources:
Buna-N 70 O-Ring Kit
Standard Seals. Our experienced sales team can help you identify the options that best suit your needs.
What applications is PTFE best suited for?
PTFE is best suited for applications that do not need a high compression set but require excellent chemical and temperature resistance, including medical devices, coatings, and pest control. It also works well in ultra-low temperatures, such as aerospace and automotive manufacturing.
Ethylene Propylene (EPDM)
Ethylene Propylene (EPDM) is an extremely durable copolymer that offers some of the best cold temperature resistance available.
Pros:
Excellent resistance to ozone, sunlight, and weathering.
Can withstand extremely cold temperatures, with an operating temperature as low as -58°F (-50°C) (with highs of 302°F (150°C)).
Compresses well.
Highly resistant to tears, abrasion, and steam.
Adheres to metal very well.
Works well with adhesives.
Cons:
What applications is EPDM best suited for?
EPDM is best suited for weatherproofing because it can withstand elements extremely well. It is frequently found in roofing, windows, doors, cell towers, and other outdoor applications. It also works well with steam applications, automotive brake fluid, vibration dampeners, and isolators.
Nitrile Butadiene Rubber (NBR)
Nitrile Butadiene Rubber (NBR) is one of the most popular elastomers, valued for its low cost and comprehensive benefits. NBR is a potential solution for harsh environments, such as extremely abrasive applications.
Pros:
Excellent abrasion resistance.
Good compression set
Good tear resistance
Good non-polar solvent resistance
Good water resistance
Good oil resistance
Cheaper than fluoroelastomers
Good low temp resistance to -65°F (-54°C)
Good oil and fuel resistance
Low cost
Cons:
Poor ozone, sunlight, and weather resistance
Limited high temperature resistance
Poor flame resistance
What applications is NBR best suited for?
NBR is used universally in basic sealing applications due to its low cost and physical properties. It is commonly found in automotive, water treatment and filtration, and pool and spa applications. In harsh environments, NBR excels in aerospace and other low-temperature applications and functions well in dynamic applications where other polymers might fail.
Making Your Final Decision
In harsh environments, choosing the right material for your O-ring is crucial, but there are numerous other considerations. You might need a different shape or size than you originally intended. While you might initially consider NBR due to its price point, it might fail so often that an FFKM O-ring could save you money in the long run despite a higher initial investment.
The best way to make your final decision is to work with a sealing expert who can offer expertise and custom solutions. For example, a manufacturer of high-pressure vessels came to our engineers at Marco Rubber looking for a solution. They needed a seal for a high-pressure, high-temperature vessel that could resist 20,000 PSI and temperatures as high as 550°F. Adding to the challenge, it had to fit into a regular O-ring groove with no backup rings.
Our team identified our proprietary high-temperature perfluoroelastomer compound, Markez Z1028, which can withstand temperatures up to 600°F. Our experts also spotted design components needing improvements to prevent the formation of an extrusion gap on the metal joints at high temperatures.
By making these changes and using the recommended Markez compound, the manufacturer had a functioning seal that passed all required testing and was put into operation.
Our FFKM line, Markez, has been the solution for many manufacturers. We have compounds to fit almost every need, including one manufactured, cleaned, and packaged in a cleanroom for ultrapure requirements. It is available at a fraction of the cost and lead time compared to other FFKM formulations, with an average lead time of 6-8 weeks.
Consider working with our experts to develop a tailored solution for your needs. Contact us today for expert advice that could save you significant effort down the line.
6 Factors to Determine the Quality of Custom Rubber Gasket
When you're looking for a custom rubber gasket for your industry application, it is vital to choose a part that offers quality assurances. A quality custom rubber gasket will fit well and prevent leaks and block the entry of contaminants for a longer time. A substandard part may cost less now but will be much more expensive if it leads to an unplanned shutdown.
How can you ensure that your rubber gasket manufacturer is offering you a high-quality part? Here are six factors to watch out for:
The Material of the Gasket
If you have given your rubber gasket manufacturer material requirements, ensure they adhere to them. Avoid cheaper lookalikes as they will prove more expensive in the long run. Higher quality materials naturally last longer and cause fewer maintenance-related shutdowns.
Manufacturing Process
The manufacturing process used while molding a custom rubber gasket is extremely important and determines the application's performance. The process can involve both cutting and punching methods for producing different gaskets for various industries. Different techniques are used to manufacture various types of gaskets. While punching is the traditional method, some product characteristics call for cutting. Ensure your rubber gasket manufacturer uses the right technique based on your requirements.
Parting Line
A parting line is a line left behind at the place where the two halves of the mold intersect. It occurs due to tiny gaps opening up when metal faces of the mold are removed. The parting or witness line can be as small as 0.0003 or as large as 0.001 inches. When there is a parting line on the gasket, it causes problems with the fit and can lead to other complications. Harkesh Rubber uses cryogenic deflashing to ensure that none of our gaskets leave a parting line behind.
Fit
This one is a bit obvious, but it’s one of the most important factors since an incorrect size will not work for your sealing needs. Make sure the gasket you’re about to buy is dimensionally accurate. Without the right fit, a gasket will be useless for your sealing application.
Shipping and Packaging Conditions
Bad shipping and packaging conditions can ruin a perfectly good rubber gasket. Check for signs of damage by inspecting the gasket's packaging. If the packaging is bent, compressed, or folded, it indicates the material has endured a compression set. Additionally, if you see signs of UV light exposure, it could shorten the gasket's life if it is made of SBR or nitrile.
Quality of the Gasket Edge
You can determine the quality of the gasket edge by the cutting process used and the condition of equipment and tooling. Even though the OD surface of a flange gasket doesn't serve any functional role, an impeccable appearance is a must. The internal edges are of great functional importance. Check for strings of material that aren't cut through properly. These strings could get into the material flow. Also, watch for any cutouts as they can create a cavity, leading to turbulence, noise, and reduced flow velocity.
Keeping the above factors in mind while purchasing a gasket, you will be able to spot a high-quality custom rubber gasket and make the best purchase decision. Alternatively, you can contact Harkesh Rubber, where we meet the most stringent quality checks and attain high precision for all custom rubber gaskets.
If you are looking for more details, kindly visit Silicone Rubber Cord.
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