Gasoline, diesel and kerosene are difficult fluids to seal. Pick the wrong material and you risk a flammable liquid leaking. In this blog we’ll discuss fuel-resistant gasket materials and why it’s important to choose from the short list of those available.
The Fuel Sealing Challenge
Hydrocarbons, the basis of most liquid fuels, cause many materials to swell. This happens because either fuel causes a chemical reaction in the material, it acts as a solvent and partially dissolves the material, or the material absorbs some of the fuel. With some fuel/material combinations all three are possible.
These changes increase the load on the joint and may make the gasket extrude out sideways. They’ll also make the material less elastic and therefore more likely to fail. What’s more, the changes aren’t reversible.
The Best Fuel-Resistant Gasket Material
The first choice for almost every fuel application should be nitrile rubber, sometimes called NBR or Buna-N. Nitrile is a synthetic rubber with a working temperature range of -30 to 200⁰F. Hardness is typically 60 – 80 shore and it resists compression set and abrasion.
Nitrile resists attack by a long list of chemicals, especially hydrocarbons like oils, greases and of course fuels. Other chemicals it withstands include ozone plus solvents like acetone and MEK.
Alternatives to Nitrile
Most fuel applications don’t need the gasket material to have a high upper temperature limit. If this is necessary the best alternative is probably FKM/Viton®. Viton remains flexible at up to 400⁰F and has similar fuel-resistance to nitrile rubber. The main reason for choosing nitrile over Viton, assuming the upper temperature is below nitrile’s limit, is cost. Viton is not cheap.
Another fuel-resistant gasket material to consider is PTFE. This lacks the compressibility and elastic recovery of nitrile or Viton but conforms readily to uneven surfaces and has a very wide working temperature range.
Nitrile Rubber From Hennig Gasket & Seals
We carry nitrile gasket material in a range of sheet thicknesses and can waterjet, flash or die-cut it to the precise geometry you need. Contact us for more information.
