Gasoline, diesel and hydraulic oil are some of the hardest fluids to seal against. They make most gasket materials swell, which increases pressure on the joint and leads to gasket failure. Nitrile rubber is one of the rare exceptions but its upper temperature limit is around 200⁰F. If you’re concerned that nitrile won’t be up to the job it’s time to move to Viton washers.
Viton™, FKM and FPM
The first thing to know about Viton is that it’s a trademark, (originally held by DuPont and now their spinoff, Chemours.) The technical term for this type of elastomer is a fluoroelastomer. In lay terms, it’s a synthetic rubber composed mostly of carbon and fluorine. In Europe fluoroelastomers are designated as FPM while here in the US we use the ASTM abbreviation of FKM. Whichever term you use, they’re essentially the same thing.
Properties of Viton and Other Fluoroelastomers
Viton and other fluoroelastomers are more expensive than almost any other gasket material, but three characteristics make them the preferred solution for the toughest sealing challenges:
- Excellent resistance to oil-induced swelling
- Highly resistant to most chemicals
- High-temperature strength (Viton goes to 400⁰F (204⁰C) and higher)
In addition, Viton has good UV and ozone resistance. Other points to note are that, while sufficient for most applications, tensile strength and resilience or elasticity are not high. Also, Viton is incompatible with acetone and many organic acids.
Applications for Viton Washers
High cost means Viton is reserved for difficult applications. Sealing pipes and fittings in fuel and hydraulic oil systems is a good example. Viton washers are a cost-effective way of minimizing the risk of potentially hazardous leaks and costly downtime in these situations. Likewise, it’s often the smart choice in systems handling corrosive chemicals where leaks must be prevented at all costs.
Viton Washers and Gaskets From Hennig
Viton comes in sheet form and a number of grades. We can water jet, flash or die cut the size and shape you need. Our specialists can help you decide what’s right for your application. Call (312) 243-8270 or 1-800-747-7661 or contact us.
