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 | Relative cost | Rating |
|---|---|---|
| HDPE $ | $$$$ | B Good |
| Polypropylene $$ | $$$$ | A Excellent |
| Nylon $$$ | $$$$ | A Excellent |
| PVDF (Kynar®) $$$$ | $$$$ | D Not Recommended |
How Caustic Soda (50%) works with the plastics used for tank fittings.
| Material | Rating |
|---|---|
| HDPE | B Good |
| PVC | A Excellent |
| CPVC | A Excellent |
| Polypropylene | A Excellent |
| PVDF | D Not Recommended |
How Caustic Soda (50%) works with gasket and O-ring materials.
| Material | Rating |
|---|---|
| Buna-N | A Excellent |
| EPDM | A Excellent |
| Viton® | D Not Recommended |
How Caustic Soda (50%) works with the metals used for fittings and bolts.
| Material | Rating |
|---|---|
| 316 Stainless Steel | B Good |
| Hastelloy | C Fair |
| Titanium | B Good |
| Aluminum | D Not Recommended |
Storing this chemical in PVDF?
PVDF tanks from 25 to 5,000 gallons with fittings installed. Confirm concentration and temperature with us before you order.
Send the chemical, concentration, temperature and size. We’ll match the tank and fittings and send a quote.