Elastomer Seal Compatibility & Swell

Chemical compatibility, thermal expansion and volume swell for twelve elastomer compounds across fifteen industrial fluids.

Elastomer compound compatibility

Elastomer Seal Compatibility & Swell calculations for elastomer compound compatibility are computed deterministically from published formulas, so the same inputs always produce the same result and the same OAS-XXXX verification hash.

Volume swell and hardness shift

Elastomer Seal Compatibility & Swell calculations for volume swell and hardness shift are computed deterministically from published formulas, so the same inputs always produce the same result and the same OAS-XXXX verification hash.

Thermal expansion and service temperature

Elastomer Seal Compatibility & Swell calculations for thermal expansion and service temperature are computed deterministically from published formulas, so the same inputs always produce the same result and the same OAS-XXXX verification hash.

Engineering summary

Governing parameters for the Elastomer Seal Compatibility & Swell silo.

Governing parameters and computed results for this calculation
Parameter Value
Compounds covered 12
Fluids covered 15
Acceptable volume swell ≤ 20 %
Thermal swell model ΔV/V = 3·α·ΔT
Reference temperature 70 °F

Frequently asked questions

What volume swell is acceptable for an elastomer seal?
Keep combined volume swell at or below 20%. Swell from 10% to 20% is workable with a wider gland, but above 20% the compound is considered incompatible and the seal will extrude or take a permanent set.
How does temperature change elastomer swell?
Thermal volumetric expansion adds to fluid swell: ΔV/V = 3·α·ΔT, where α is the linear expansion coefficient. A compound at 250 °F above a 70 °F reference gains several percent of thermal swell on top of its fluid swell.
Which elastomer resists Skydrol and phosphate-ester fluids?
EPDM and PTFE resist Skydrol and phosphate esters, while nitrile and fluorocarbon swell heavily. For aviation hydraulic service, EPDM is the standard choice; PTFE is used where near-zero swell is required.