Caustic Soda (50%) (sodium hydroxide, NaOH, CAS 1310-73-2) is the most common form of liquid caustic, a clear, viscous, strongly alkaline solution with a specific gravity of about 1.52. It begins to crystallize near 54°F (12°C), so outdoor tanks are often insulated and heated. 50% caustic soda is used in pulp and paper, alumina refining, soaps, textiles, water treatment pH control and chemical manufacturing. Use the compatibility ratings to choose the right tank resin, fittings and gaskets.
Safety data: Caustic Soda Solution Safety Data Sheet (SDS) – Formosa Plastics USA
Polypropylene is the most economical tank material for Caustic Soda (50%), rated Excellent. Nylon and HDPE are also rated Good or better. Avoid PVDF (Kynar®) tanks, PVDF fittings, Viton® gaskets and aluminum hardware. Rated Fair (contact us before use): Hastelloy hardware.
How Caustic Soda (50%) works with the plastics used to make our storage tanks.
| Material | Rating |
|---|---|
| HDPE | |
| Polypropylene | |
| Nylon | |
| PVDF (Kynar®) |
How Caustic Soda (50%) works with the plastics used for tank fittings.
| Material | Rating |
|---|---|
| HDPE | |
| PVC | |
| CPVC | |
| Polypropylene | |
| PVDF |
How Caustic Soda (50%) works with gasket and O-ring materials.
| Material | Rating |
|---|---|
| Buna-N | |
| EPDM | |
| Viton® |
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