Ethylene-propylene (EPDM) compounds are prepared from ethylene, propylene and a third monomer. These compounds are used frequently to seal phosphate ester fire resistant hydraulic fluids such as Skydrol. They are also very effective in brake systems and for sealing hot water and steam. Ethylene-propylene compounds have good resistance to mild acids, alkalis, silicone oils and greases, ketones, and alcohols. They are not recommended for petroleum oils or diester lubricants.

Ethylene-propylene has a temperature range of -65° to 300°F (-55° to 150°C). It is compatible with polar fluids that adversely affect other elastomers.

PAI offers EPDM compounds in a hardness range of 40 to 90 durometer. Black is the standard color, but many other colors are available