Compare the operating medium and environment before selecting a compound.
Start with fluid contact
EPDM is often considered for weather exposure and selected water-based environments. NBR is often considered for oil-contact applications. Neither family name establishes compatibility with an unspecified mixture.
Compare actual compounds
Review source data for the candidate compound, including temperature, compression set, aging and relevant chemical testing. Compare like test methods and conditions.
Include the complete environment
Ask about low-temperature starts, cleaning chemicals, outdoor aging, seal movement and pressure cycling. One requirement may rule out an otherwise plausible material.
Confirm with application data
Use the exact fluid, concentration and duty cycle in a material review. Where failure matters, define validation testing before approving production.