Elasto Proxy's Sealing Solutions Blog Blog

Elasto Proxy's Sealing Solutions Blog

Elasto Proxy's Sealing Solutions Blog is the place for conversation and discussion about the design and manufacturing of rubber and plastic parts and products. In addition to regular content from Elasto Proxy, you'll hear from companies across the rubber and plastics industry.

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Fluorosilicone Gaskets for Sealing and Insulation

Posted August 10, 2015 4:59 PM by Doug Sharpe

Fluorosilicone gaskets combine the high and low temperature resistance of silicones with the fuel and oil resistance of fluorocarbons. Some fluorosilicone gasket materials also resist abrasion and provide EMI shielding. Is fluorosilicone the right rubber for your gasketing application?

Fluorosilicones combine the temperature resistance of silicones with the fuel, oil, and solvent resistance of fluorocarbons. Applications for these extreme-environment elastomers include automotive, aerospace, and defense. For technical buyers and design engineers, however, choosing the right rubber may involve more than specifying a temperature range, oil or fuel type, and industry. Is flurosilicone right for your sealing and insulation application? If so, are you looking for custom fabrication expertise?

Fluorosilicone Properties and Applications

Flurosilicone's mechanical properties vary with service temperature, and some compounds provide resistance to abrasion and electromagnetic interference (EMI). In addition to fuel line seals, engine gaskets, and exhaust gas recirculating diaphragms, fluorosilicone rubber is used in O-rings, tank linings, protective boots for electrical equipment, and in plasma ashing equipment for the semiconductor industry. Metal-filled fluorosilicones provide electrical conductivity, too.

Fluorinated Silicone Rubber

Like other silicone compounds, fluorosilicone rubber (FSR, FVMQ) resists high temperatures, low temperatures, ozone, aging, ultraviolet light, and weathering. Typically, FSR or FVMQ rubbers are blended with dimethyl silicones, elastomers that provide good temperature stability. Silicones, a large family of synthetic rubbers, are used in environmental sealing and are chemically inert. These elastomers also have good dielectric properties and are available as molded rubber products and extrusions.

FSR Rubber for Fluid Resistance and Abrasion Resistance

Fluorinated silicone rubber contains fluorine additions that impart resistance to hydrocarbon fluids such as jet fuels. These synthetic elastomers also resist oxidizing chemicals, chlorinated solvents, aliphatic and aromatic fluorocarbons, silicone oil, and animal and vegetable oils. Although some FSR rubbers have poor abrasion resistance, others have benefited from advancements in fluorosilicone chemistry. For example, some FSR elastomers have an abrasion resistance that's superior to FKM or Viton.

Fluorosilicones for Static and Dynamic Sealing

Traditionally, fluorosilicones were used only in static sealing applications. Thanks to their improved abrasion resistance, however, some FSR materials are now used in dynamic applications such as sliding shaft seals and rotating seals. Other types of oil-resistant rubbers are available, but FVMQ may be the right choice for your sealing application because of its fuel resistance, outstanding low-temperature flexibility, and low compression set.

Electrically-Conductive Fluorosilicone for EMI Shielding

Fluorosilicone compounds that are filled with metal particles or thin strands of metal wire combine environmental sealing with EMI shielding. The insulation that these conductive shielding elastomers provide makes them a good choice for industrial, commercial, and military applications. Examples include fluorosilicones that are filled with silver-nickel or silver-aluminum particles, or that contain Monel or aluminum wires. Shielding silicones that that meet MIL-DTL-83528C requirements are available.

Custom Fluorosilicone Gaskets

Do you need help determining if fluorosilicone is right rubber for your application? If FSR or FVMQ rubbers meet your requirements, do you know which kind of compound you need? Elasto Proxy keeps hundreds of rubber profiles in stock, and can source fluorosilicone compounds that meet your application requirements. With our custom fabrication expertise, we can also create specialty flurosilicone gaskets for sealing and insulation.

How can we help you? Download this document to learn more about our technical design and custom fabrication capabilities.


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Join Date: Jun 2009
Location: South of Minot North Dakota
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Re: Fluorosilicone Gaskets for Sealing and Insulation

08/10/2015 5:15 PM

Personally I would love to see the stuff being put into the average small engine and lawn and garden machine market into the form of fuel lines, primer bulbs and carburetor gaskets/O-rings being as of now the present plastics they are using for those items are not fully compatible with the newest fuel formulas and tend to rot out and or dissolve after only a few months to a year or two of exposure to the fuel and sunlight at the same time.

Add in the higher than ambient heat those machines little engines make and where they run fuel lines through them plus the ever ongoing issue of ethanol or something else they are putting in today's gasoline and the old fuel line materials just cant cut it for chemical compatibility long term.

BTW personally I have been running most of my lawn and garden equipment and other small engines on E30 or higher ethanol blends for a few years now and I have yet to see that ethanol is the sole cause of fuel line/component rot out.

My dad and brother have been the control groups, without there knowing it being they will not run ethanol blended fuel in their equipment, and I do as many fuel system related repairs to their equipment as mine for the exact same reasons.


Join Date: Nov 2010
Location: Virginia, Georgia, Idaho
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Re: Fluorosilicone Gaskets for Sealing and Insulation

08/10/2015 11:34 PM

Great point, TCM. Our company runs B10 in our diesel trucks. We see no difference in average maintenance costs, but inevitably, some old diesel mechanic will blame a failed injector on the biodiesel. We use it because we like to see people farm fuel, instead of dug it up.

PFR Pressure busts pipes. Maybe you need better pipes.
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