Potassium Hydroxide Resistant O-Rings
Compatibility ratings for 7 O-ring materials in Potassium Hydroxide service
Potassium Hydroxide (Bases) compatibility with the seven most common O-ring elastomers, rated on the standard A/B/C/D scale: A = excellent, B = good, C = fair, D = not recommended. This data also appears in our interactive chemical compatibility chart and is available machine-readable at /api/chemicals.json.
| Material | Rating | Guidance |
|---|---|---|
| NBR | B | good — suitable for most applications |
| FKM | C | fair — conditional use, verify with testing |
| EPDM | A | excellent — recommended for continuous service |
| VMQ | C | fair — conditional use, verify with testing |
| PTFE | A | excellent — recommended for continuous service |
| FFKM | A | excellent — recommended for continuous service |
| HNBR | B | good — suitable for most applications |
Why These Ratings
- EPDM (A) — documented strengths include “Dilute acids and alkalis.”
- VMQ (C) — documented weaknesses include “Concentrated acids and alkalis.”
- PTFE (A) — documented strengths include “Virtually all chemicals.”
- FFKM (A) — documented strengths include “Virtually all chemicals except molten alkali metals.”
BasesService: Concentration & Temperature Notes
Caustic service inverts the usual hierarchy: EPDM outperforms FKM here (A versus C in our sodium- and potassium-hydroxide rows). Amine-containing bases are harder on FKM than hydroxides — FKM rates D in ammonia service. Hot caustic is dramatically more aggressive than cold; validate any caustic application above +50°C with immersion testing.
Recommended
- EPDM O-rings (A)
- PTFE O-rings (A)
- FFKM O-rings (A)
Use With Caution
- NBR O-rings (B)
- FKM O-rings (C)
- VMQ O-rings (C)
- HNBR O-rings (B)
Avoid
No material is rated D for this chemical.
Related Chemicals (Bases)
Frequently Asked Questions
Is Potassium Hydroxide compatible with FKM (Viton) O-rings?
FKM is rated C for Potassium Hydroxide: fair — conditional use, verify with testing. Ratings are general guidelines; concentration, temperature and exposure time all affect real-world compatibility, so validate critical applications with ASTM D471 immersion testing.
Is Potassium Hydroxide compatible with NBR (nitrile) O-rings?
NBR is rated B for Potassium Hydroxide: good — suitable for most applications. NBR is the lowest-cost elastomer, so when it earns an A or B rating it is usually the economical default; when it rates C or D, do not substitute it for a higher-rated material to save cost.
Can I use PTFE O-rings with Potassium Hydroxide?
PTFE is rated A for Potassium Hydroxide: excellent — recommended for continuous service. Remember that PTFE has no elastic memory — in demanding service it needs spring energization or an elastomer core (FEP/PFA encapsulation) to maintain sealing force.
What is the best O-ring material for Potassium Hydroxide?
EPDM, PTFE, FFKM are rated A (excellent) for Potassium Hydroxide in our compatibility data and are the recommended starting point for material selection. Final selection should also account for operating temperature, pressure and whether the seal is static or dynamic.
Can I use EPDM O-rings with Potassium Hydroxide?
EPDM is rated A for Potassium Hydroxide: excellent — recommended for continuous service. Always confirm the specific fluid concentration and temperature before specifying EPDM for this service.
Need O-Rings for Potassium Hydroxide Service?
Send us your fluid, concentration and temperature — our engineers will confirm the right compound. MOQ 1 piece.