FAQ EPDM or Viton

This FAQ contains frequently asked questions about EPDM or Viton seals that are used in the VARIBOX. This FAQ explains about seals used in the VARIBOX and their materials. It also helps to choose the correct material for your application. At the end you will find a general guidance table.

What are gaskets?
You will find seals in the screw cap, combi vent, extractor tubes and level sensors. Seals ensure the leak tightness of closures, so chemicals and fumes stay inside. The VARIBOX can be equipped either with EPDM seals, or with Viton seals.


What is EPDM?
EPDM is a material used for the seals (gaskets) in many VARIBOX components. EPDM is an elastomer and is short for Ethylene Propylene Diene Monomer, a type of synthetic rubber.
How resistant is EPDM?
EPDM has a good resistance to many chemical products like detergents, caustic potash solutions, sodium hydroxide solutions and many other diluted acids and chemicals. It is not resistant to most hydrocarbons, such as oils, kerosene, gasoline and many solvents. EPDM is resistant to steam and ozone.


What is Viton?
Viton is a material used for the seals (gaskets) in many VARIBOX components. Viton® is a registered trademark of The Chemours Company and is an FKM material. This is a fluoro elastomer, another type of synthetic rubber. When a VARIBOX is equipped with Viton, the seals in the CDS extractor tube will be made of Aflas®. This is TFE/P, another fluoro elastomer, from the Asahi Glass Ltd
How resistant is Viton?
Unlike EPDM, Viton has a good resistance to oils, fuels, lubricants, and most mineral acids. It is resistant to most chemicals, but not to for example Acetic acid, Ammonia, Caustic soda, Formic acid and Potassium hydroxide.

Which material is better?

Is Viton better than EPDM?
This question cannot be answered in general: in many cases both materials will be resistant to the chemical product in the VARIBOX. But some chemicals are not compatible with EPDM, and Viton is the better choice. And some chemicals are not compatible with Viton and EPDM is the better choice.
How do I choose the correct sealing material?
A general guidance on regularly filled chemical products is listed in the table below. Check the resistance of these seals against the product that you want to fill into the VARIBOX. Some chemical products are causing strong deterioration of EPDM as well as Viton, like Hydrofluoric acid and Nitric acid in high concentrations. With these chemicals we advise you to choose Viton as it outperforms EPDM. Regularly inspect the quality of the seals. Especially at elevated temperatures the seals may deteriorate quickly and need to be replaced.
ProductConc.FormulaUN number(s)Gasket material
Acetic acidAllCH3OOHUN2789 UN2790EPDM
Citric acidAllC6H8O7UN3265EPDM
Hydrofluoric acid<60%AllHFUN1790Viton
Phosphoric acidAllH3PO4UN1805EPDM
Potassium hydroxideAllKOHUN1814EPDM
Sodium chloriteAllNaCIO2UN1908EPDM
Sodium hydroxideAllNaOHUN1824EPDM
Sodium hypochloriteAllNaOCIUN1791*EPDM
Peroxyacetic acid<5%C2H4O3UN3149*Viton
Peroxyacetic acid15%C2H4O3UN3109*Viton
Nitric acid<55%HNO3UN2031Viton
Nitric acid55-62%HNO3UN2031Viton
Hydrogen peroxide<60%H2O2UN2014*; UN2984*Viton
Hydrochloric acidAllHCIUN1789Viton
Sulfuric acidAllH2SO4UN1830Viton

*Warning: overpressure relief vent is required or advised

More information

Do you have any other specific questions regarding the EPDM or Viton seals on the VARIBOX or do you want additional information please feel free to contact us by info@varibox-ibc.com or you can call (+31) 0570-660-706