Made for movement, stretch and assembly strain.
With 224% elongation, Aperflu 3175 is the most compliant compound in the family. Dynamic seals need a material that follows shaft runout and eccentricity without building stress — that is precisely where this grade belongs.
Hardness of 72 Shore A and 18.3 MPa tensile keep it strong enough for real gland pressures, while the 290 °C two-stage post-cure gives a fully crosslinked network with 21% compression set at 200 °C. Choose it when the seal must deform repeatedly, not just once.
Two opposite design intents. Aperflu 3175 is the compliant grade — 224% elongation for dynamic seals and stretch installation; Kalrez 7375 is a harder, tightly crosslinked compound for static high-temperature chemical and steam service. The compression-set comparison is unusually clean: both are measured on AS568-214 O-rings over 70 h at about 200 °C, and there 7375 is clearly ahead.
| Property | Aperflu 3175 | Kalrez 7375 |
|---|---|---|
| Hardness | 72 Shore A | 79 Shore A |
| Tensile strength at break | 18.3 MPa | 16.9 MPa |
| Elongation at break | 224 % | 128 % |
| Compression set, 70 h | 21 % @ 200 °C | 9 % @ 204 °C |
| Max. application temperature | Not published | 300 °C |
Highlighted cells indicate the more favourable published value.
96 points more elongation (224% vs 128%) and 8% higher tensile strength. That compliance is what dynamic seals need: it follows shaft runout, eccentricity and misalignment, and it survives stretch installation over flanges without taking a permanent set.
Less than half the compression set on the same O-ring basis (9% vs 21%), a published 300 °C application ceiling, and a crosslinking system explicitly rated for water/steam and oxidizing chemicals — a service window 3175 does not publish data for.
Reciprocating and dynamic seals, wide-tolerance grooves, large-diameter O-rings that must stretch over a flange: 3175. Static high-temperature seals in steam or oxidizing media where set resistance and a documented temperature ceiling drive the decision: 7375.
Kalrez® and Spectrum™ are trademarks of DuPont de Nemours, Inc. Kalrez 7375 values are taken from DuPont published product datasheets (Dec 2019 / 2021); Aperflu 3175 values are taken from its compound technical data sheet. All figures are typical values, not specifications. Compression set is the most directly comparable property here — both datasets use AS568-214 O-rings, 70 h, ASTM D395B — but the set temperatures differ slightly (200 °C vs 204 °C). Confirm selection with immersion testing in the actual process fluid.
High elongation absorbs shaft runout, eccentricity and misalignment without stress cracking.
Tolerates larger dimensional variation, reducing scrap and assembly rework.
Stretch installation over flanges and covers without permanent distortion.
Send us your media, temperature and pressure profile — we will recommend the grade.