O-ring material
Kalrez® O-Rings
Kalrez is the FFKM line made by Qnity Electronics, the DuPont electronics spin-off that took the brand with it in November 2025. Conquest supplies Kalrez O-rings in AS568 and metric sizes as an independent distributor: every Kalrez part is molded by the brand owner, and the grade number on the print decides the part. On the maker's sheets on file, Kalrez 0040 is rated down to -42 C at the cold end and Kalrez 7075 up to 327 C at the hot end.
- Family
- FFKM, perfluoroelastomer (ASTM D1418); Kalrez is Qnity Electronics' brand
- Standard range
- -26 C to 320 C for the FFKM family (Parker® O-Ring Handbook ORD 5700)
- Grades on file
- Chemical process: 6375, MS220, 4079, 7075, 7090, 7275, 7375, 7390, 6380, 0040, 0090. Semiconductor: 9100, 9300, 9500, 8002, 8085, 8900, 8475, 6375UP, 1050LF
- Durometers
- 75 Shore A on most grades; 70 (0040), 80 (6380), 90 (7090) and 95 (0090) A
- Standards
- ASTM D1418 FFKM; the maker lists 0090 to NORSOK M-710 sour aging and offers ultrapure (UP) cleaning on the semiconductor grades
- Product
- O-rings in AS568 and ISO 3601 sizes, quoted by grade; supplied as finished parts from the brand owner
Service temperatures here are the family figures published in Parker O-Ring Handbook ORD 5700 service temperature table, page 7-2; the compound datasheet and your application govern the final choice.
Who owns Kalrez, and what that changes
Kalrez was a DuPont product for decades, and the selector guides still carry DuPont's name and form numbers. Since 2025 the brand belongs to Qnity Electronics, the company DuPont spun off with its electronics business. The grades, the grade numbers and the sheets did not change with the owner. What you should check is that a certificate names the maker as it is now.
The chemical-process grades
Qnity's selector guide for the chemical process industry sorts the line into general-purpose and specialty grades. The general grades are the maker's broad chemical grades; the specialty grades each fix one problem, and the maker says plainly which media each one is not for. The table is our reading of that guide, sorted by the maker's maximum figure rather than by the guide's own sequence, with each grade's purpose in our words.
| Grade | What it is for (our words) | Color | Shore A | Low, C | High, C |
|---|---|---|---|---|---|
| Spectrum® 7075 | The hottest-running grade in the line and the one with the least set at heat; keep it out of steam | Black | 75 | -18 | 327 |
| Spectrum 7090 | The same heat in a 90 durometer: pressure, extrusion gaps and gas decompression | Black | 90 | -26 | 325 |
| 4079 | Older high-heat grade with strong mechanicals; steam, hot amines and the epoxides are off its list | Black | 75 | -19 | 316 |
| Spectrum 7375 | The grade the maker built for hot water and steam | Black | 77 | -20 | 300 |
| Spectrum 7390 | Hot water and steam in a harder grade, 89 Shore A | Black | 89 | -22 | 300 |
| Spectrum 7275 | A light-brown grade for oxidizers and reactive monomers: nitric acid, silanes, the epoxides | Light brown | 75 | -20 | 300 |
| Spectrum 6375 | The broad chemical grade and the usual first quote; covers acids, bases, amines and steam | Black | 75 | -20 | 275 |
| 0090 | A 95 durometer for gas decompression and sour service; holds an extrusion gap without a backup ring | Black | 95 | -27 | 250 |
| MS220 | A chemical grade the maker positions as an alternative to 6375 where service stays within its own narrower range | Black | 76 | -14 | 230 |
| Spectrum 6380 | Cream-colored, made for hot aggressive amines | Cream | 80 | -22 | 225 |
| Spectrum 0040 | The cold grade: the lowest starting temperature in the line | Black | 70 | -42 | 220 |
The figures matter most at the edges. Kalrez 7075 is rated by its maker from -18 C to 327 C, and Kalrez 0040 is rated down to -42 C, which is a cold limit no other grade in the line reaches. Kalrez 6375 is rated from -20 C to 275 C and is the maker's broadest chemical grade. The maker calls these typical values and says not to use them as specification limits.
The semiconductor grades and the UP suffix
The semiconductor selector guide sorts a second set of grades by process rather than by medium: plasma etch and deposition, thermal processes such as diffusion and CVD, and wet processes. These grades are chosen for how little they erode and how few particles they shed in a chamber, and the maker publishes a maximum continuous temperature for each with no minimum. Kalrez 8900 is rated to 325 C for thermal processes and Kalrez 9100 to 300 C for plasma deposition, by the maker's figures.
| Grade | Where it goes (our words) | Color | Shore A | Maximum, C |
|---|---|---|---|---|
| 8900 | Furnace and thermal work: oxidation, diffusion, the CVD and ALD family; the hottest of the chamber grades | Black | 73 | 325 |
| 9500 | Chambers that see ozone, ammonia and water vapor along with plasma radicals | Tan | 75 | 310 |
| 9100 | Plasma deposition chambers where erosion and particles must stay lowest | Amber translucent | 68 | 300 |
| 9300 | Etch chambers where ion bombardment and radicals attack together | Brown | 74 | 300 |
| 8475 | Lamp-heated anneal and rapid thermal tools; low sealing force, less infrared uptake | White | 60 | 300 |
| 1050LF | Wet benches that need the best compression set of the wet grades | Black | 82 | 288 |
| 8002 | Unfilled and clear; strip and select etch or deposition where cracking under plasma is the risk | Clear | 69 | 275 |
| 6375UP | The general wet-process grade, cleaned and packed ultrapure | Black | 75 | 275 |
| 8085 | A beige grade for NF3-cleaned deposition chambers; short excursions above its figure are allowed by the maker | Beige | 80 | 240 |
The UP suffix means ultrapure post-cleaning and packaging: the maker cleans the parts in a Class 100 room, rinses them in ultrapure water and double-bags them. It is standard on the plasma and thermal grades and can be specified on others by adding UP to the grade. Ask for it by name if the part goes into a chamber.
Reading a Kalrez callout
A print that says Kalrez and a four-digit grade is asking for that grade from Qnity, in the AS568 size it names. A print that says Kalrez alone is incomplete; ask which grade, because the steam grade and the high-temperature grade are not interchangeable. Spectrum is the maker's name for the newer part of the line and changes nothing in the part number. UP after a grade is the cleaning and packaging level, not a different compound.
When the print says "or equal"
An "or equal" opens the print to another maker's grade in the same family, and the decision is your engineering's, not ours. The brands and grades cross-reference lists the families across Chemraz®, Simriz®, Perlast®, Isolast® and Parofluor® with the maker figures on file, so the comparison starts from sheets rather than folklore. Tell us which equal you have approved and Conquest quotes that part; where you have not, we quote Kalrez as named. The branded vs generic FFKM guide covers what the brand buys you.
Sizes and forms we supply
All 369 AS568 sizes (349 general-purpose dash sizes plus the 20 boss-seal sizes) and the ISO 3601 metric series, in the durometers listed above. The AS568 chart and the metric chart carry the dimensions, and the dash number guide explains the numbering.
Sources: Kalrez Perfluoroelastomer Parts in Chemical Process Industry, Product Selector Guide KZE-A40126, Qnity Electronics (formerly DuPont), November 2022, read 2026-09-14; Kalrez Semiconductor Product Selector Guide KZE-H88232, DuPont, February 2012, read 2026-09-14; Parker O-Ring Handbook ORD 5700, section 2.2.10 (read 2026-09-14); Qnity Electronics, Kalrez brand pages (ownership since 2025-11-01), read 2026-09-14.
Parker is a trademark of Parker Hannifin Corporation. Kalrez and Spectrum are trademarks of Qnity Electronics; Chemraz is a trademark of Greene Tweed; Simriz is a trademark of Carl Freudenberg KG (Freudenberg Sealing Technologies); Perlast is a trademark of Precision Polymer Engineering; Isolast is a trademark of Trelleborg Sealing Solutions; Parofluor is a trademark of Parker Hannifin. No affiliation or endorsement is implied.
Reviewed by Grant Midstokke, Conquest Seal Corporation. Last updated September 2026. Material ranges are the published references named beside them; the compound datasheet and your application govern the final choice.
Frequently asked
Who owns Kalrez now?
Qnity Electronics, the electronics business DuPont spun off in November 2025. The grades and sheets are unchanged; check that the certificate names the maker as it is now.
Can Conquest supply Kalrez?
Yes, as an independent distributor of finished parts. Conquest does not mold the polymer and does not claim to; the part comes from the brand owner and the quote names the grade.
Which Kalrez grade is the general one?
Kalrez 6375, the maker's broadest chemical grade, rated by the maker from -20 C to 275 C. If your service is steam, dry heat above that, cold, or a semiconductor chamber, the specialty grades above are the ones to name.
Which Kalrez grade for steam?
Kalrez 7375, or 7390 where a harder grade (89 Shore A on the maker's sheet) is wanted; the maker positions both for hot water and steam and keeps 4079, 7075 and 7090 out of it.
Is Chemraz an equal?
That is your engineering's call, not ours. Chemraz is Greene Tweed's FFKM line with its own grade families and sheets; the cross-reference guide puts the figures side by side, and Conquest quotes the equal you approve.
What does UP mean after a Kalrez grade?
Ultrapure post-cleaning and packaging by the maker: cleaned in a Class 100 room, rinsed in ultrapure water, double-bagged. It changes the handling, not the compound.
Related guides
Send the part number and the quantity for Kalrez
The AS568 dash number or the inside diameter and cross-section, the durometer, the quantity, the medium and temperature, and any specification the print names. A Conquest representative replies.
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