FKM (Generic for Viton) are made from the same fluoro rubber, and share the same high acid resistance. These FKM gaskets offer the good performance against oils and fats while still maintaining good resistance to acids and alkalis. Can swell when in contact with Nitric, Formic and peracetic acids and weakened by strong caustic. Ideal for bio-diesel and other fuel applications but is not considered a food-safe product.