Kalrez alternatives: FFKM O-rings supplied in Asia
Short answer: the FFKM alternatives to DuPont Kalrez that MST supplies are Greene Tweed Chemraz 513 and the MORISEAL Morisz grades from China. Match the Kalrez grade you use by temperature, hardness and process: for example Kalrez 8705 (77A, 327 °C) is closest in rating to Morisz N65 (75 ± 5 HA, 0–330 °C).
MST ships from Asia, quotes standard AS568 sizes and custom sizes, and accepts small quantities for qualification.
Kalrez grades and published alternatives
| Kalrez grade | Kalrez rating | Alternative | Alternative rating | Published application |
|---|---|---|---|---|
| Kalrez 8705 | 77A, 327 °C | MORISEAL Morisz N65 | 75 ± 5 HA, 0–330 °C, compression set 11 % | Plasma sealing at elevated temperature |
| Kalrez 9600 | 70A, 315 °C | MORISEAL Morisz 6880SZ | 80 ± 5 HA, 0–315 °C, compression set 9 % | High-temperature plasma under mechanical stress |
| Kalrez 9300 / 9100 | 77A / 70A, 300 °C | MORISEAL Morisz 5802SP / 6002UP | 75 ± 5 / 80 ± 5 HA, 0–300 °C | High-temperature seals exposed to water vapour, oxygen or ozone |
| Kalrez 8002 | 69A, 275 °C | MORISEAL Morisz 5130UP | 80 ± 5 HA, −5–250 °C, compression set 22 % | Dynamic sealing in plasma |
| — | — | Greene Tweed Chemraz 513 | 80 Shore A typical, 210 °C reference limit | Semiconductor dry process |
| — | — | MORISEAL Morisz ST50I | 65 ± 5 HA, −45–200 °C | Low-temperature sealing |
MORISEAL compression set measured at 200 °C / 70 h. Ratings are not equivalence: qualify the alternative in your chamber.
How to switch from Kalrez
- Note the Kalrez grade, size (AS568 dash number or ID × CS) and location in the tool.
- Pick the alternative whose temperature range covers your peak seal temperature.
- Keep a similar hardness for the same gland; harder grades resist extrusion, softer grades seal at lower force.
- Order a small qualification lot and run it through your normal PM interval.
Frequently asked questions
What is a good alternative to Kalrez O-rings?
Greene Tweed Chemraz 513 and MORISEAL Morisz FFKM grades. For high-temperature plasma, Morisz N65 (0–330 °C) and 6880SZ (0–315 °C) are rated close to Kalrez 8705 and 9600.
Who supplies Kalrez alternative FFKM O-rings in Asia?
MST supplies Greene Tweed Chemraz and MORISEAL Morisz FFKM O-rings from Asia, in AS568 and custom sizes.
Who makes Morisz?
MORISEAL, a seal manufacturer in China. Morisz is its FFKM material series.
Can I buy a small quantity for qualification?
Yes. Request a quote from 1 piece; minimum order and packing quantity are stated in the quote.
Is MST the manufacturer?
No. The seals are made by Greene Tweed and MORISEAL; MST is the distributor.
Ask an engineer
Send the Kalrez grade, size, process and quantity. MST, as distributor, quotes the matching Chemraz or Morisz grade.
Request a quoteRelated pages
Sources
- DuPont Kalrez plasma selector guide (KZE-A40111-00-A0422)
- MORISEAL product centre
- Greene Tweed Chemraz 513 listing
Values are taken from the manufacturer documents above, checked 2026-10-26. Specifications can change; confirm against the current datasheet before ordering. MST is a distributor; products are made by the manufacturers named.