Seal Thermal Stability

Low Temperature Seal Thermal Stability

The low-temperature limit is generally 15°F below TR-10 for static seals. For dynamic seals the TR-10 is more relevant. The TR-10 is the temperature at which an elastomer is able to retract 10%.

Low-temperature performance is generally a reversible process.

For design purposes compression is generally increased. The chemical media may cause swelling which may act as a plasticizer and lower the service temperature.

Definition of:

Glass Transition Temperature:

TR Tests: ISO 2921, ASTM D1414, D1329

Stiffness: ISO 1432, ASTM D1053, D2240

Brittleness: ISO R812, ASTM C509

Crystallization: ISO 3387, 6471

low temperature limits of various sealing elastomers

Thermal Expansion

Material	Units	Therm. Stab.	x10^–5 /°C	x10^–6 /°F
FKM		200°C	16	90
NBR		120°C	23	62
VMQ		230°C	59–79	103
FFKM		300°C	23
EPDM		150°C	16
Stainless		–	1.04
Aluminum		–	1.3
TEFLON		230°C	5–8
KEL-F		280°C	4–7
Polyimide		275°C	5

	Thermal Conductivity (g-cal/sec/cm²/cm/C)	Specific Heat (cal/g/C)
VMQ	0.330–0.515 x 10^–3	0.28–0.35
SC1030/SC1020	0.6/0.8 x 10^–3	0.2

High Temperature Seal Thermal Stability

The high-temperature limit for seal thermal stability is generally considered a 30–50% loss of physical properties and typically represents a maximum temperature for 1,000 hours continuous service. It represents an irreversible change in the backbone or cross-link network.

The effect of high temperature can be compounded by the interaction with the chemical media. Chemical reactions typically double with a 10°C increase in temperature.

Definition of:

Thermal Conductivity: ASTM C177, C518
Thermal Expansion: ASTM D864
Heat Aging: ISO 188, ASTM D454, D572, D573, D865

high temperature vs. lifetime

high-temperature limits of various sealing elastomers

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