Potassium Hydroxide (Caustic Potash) Storage — Tank System Selection
Storing Potassium Hydroxide (KOH)? Start Here
Potassium hydroxide — caustic potash — is a strong base used in soap making, biodiesel, and industrial cleaning. It's an easy, low-corrosion chemical to store in poly, with one gasket rule that trips people up: use EPDM, not Viton. Viton gets attacked by strong bases.
Can you store it in a poly tank? Easily.
KOH solution is compatible with HDPE and XLPE chemical-service tanks (1.9 SG). Use EPDM gaskets, PVC fittings, and 316 stainless bolts. EPDM is the correct gasket — Viton degrades in strong caustic. Poly itself shrugs KOH off; the care is in seals and temperature.
The safety that actually matters
- EPDM gaskets — not Viton (strong bases attack Viton).
- Dilution gives off heat — add KOH to water slowly, never the reverse.
- Strongly caustic — eye/skin protection, eyewash/shower nearby, 110% containment.
- Keep concentrated solution from getting cold, which can cause it to thicken or crystallize — insulate or heat outdoor tanks.
Common questions
- Viton or EPDM for KOH?
- EPDM. Strong bases attack Viton — same rule as sodium hydroxide.
- Is KOH hard on poly tanks?
- No — polyethylene handles caustics well. The attention goes to seals and keeping it warm enough to stay pumpable.
- Anything when diluting?
- It releases heat — add caustic to water slowly and protect your skin and eyes.
Potassium Hydroxide (Caustic Potash) storage tanks from OneSource
For potassium hydroxide (caustic potash) storage, specify HDLPE_OR_XLPE rated to specific gravity 1.9. Verified, compatibility-matched options:
- Snyder Industries 22 Gallon ASTM XLPE Black Heavy Duty Vertical Storage Tank (1.9 SG)
- Snyder Industries 150 Gallon XLPE Chemical Feed Station Tank (1.9 SG)
- Snyder Industries 500 Gallon ASTM XLPE Black Double Wall Tank (1.9 SG)
- Snyder Industries 1500 Gallon 45 Degree XLPE Cone Bottom Tank in White (1.9 SG)
- Snyder Industries 5000 Gallon XLPE Vertical Liquid Storage Tank with ASTM Certification (1.9 SG)
Confirm chemical compatibility and a ZIP freight quote with our team at 866-418-1777.
Sources & References
All compatibility ratings, hazard classifications, and chemical identifiers on this page are sourced from authoritative third-party publications. Verify against the original references before final specification.
- PubChem Compound Database — entry for Potassium Hydroxide (CID 14797, CAS 1310-58-3). pubchem.ncbi.nlm.nih.gov. National Library of Medicine / NCBI. Canonical chemical-identity reference.
- Snyder Industries Chemical Resistance Recommendations — system-of-construction guidance for polyethylene chemical-storage tanks at industrial ASTM 1.9 SG design rating. SNY-3041 Chemical Resistance Chart. Snyder Industries, current edition. Resin + fitting + gasket + bolt MOC matrix.
- Equistar Technical Tip — Chemical Resistance of Polyethylene — LDPE / MDPE / HDPE rating chart by concentration and temperature, distributed by Enduraplas. enduraplas.com (PDF). Equistar polyethylene resin chemical-resistance data, distributed via Enduraplas.
- NFPA 704: Standard System for the Identification of the Hazards of Materials for Emergency Response. nfpa.org. NFPA 704 'fire diamond' health/flammability/instability/special-hazard rating system (0–4 scale).
- UN Globally Harmonized System of Classification and Labelling of Chemicals (GHS), current revision. unece.org/transport/ghs. GHS pictograms, signal words, and H-statement codes referenced in this guide.
- ASTM D1998 — Standard Specification for Polyethylene Upright Storage Tanks, current edition. astm.org. Cited as the design-specific-gravity standard (typically 1.9 SG) for industrial chemical-service polyethylene tanks.
- NIOSH Pocket Guide to Chemical Hazards — occupational exposure limits, PPE, and IDLH data for Potassium Hydroxide. cdc.gov/niosh/npg. CDC / NIOSH chemical-specific occupational-safety reference.