Pumps for Sodium Hydroxide (NaOH, Caustic Soda)
Why sodium hydroxide is hard on pumps
Caustic soda has a different failure catalog than the acids. It attacks aluminum, zinc, and galvanized hardware outright, and hot caustic stresses metals that handle it cold. Concentrated solutions turn viscous as they cool and can solidify in unheated lines, so pumps see thick, reluctant fluid at startup. The quietest killer is crystallization: caustic that weeps past a mechanical seal dries into hard, abrasive crystals that grind the seal faces on the next start. And because caustic causes severe burns, a leak is a personnel problem before it is a maintenance problem.
Approaches that get specified
Sealless pump designs, magnetically driven or peristaltic, remove the seal that caustic crystallization destroys, and they are the first thing we look at for concentrated caustic. Engineered thermoplastic wetted parts cover the common caustic services without the corrosion allowances metal designs carry. For pH adjustment and neutralization feed, digital dosing pumps meter caustic precisely across a wide turndown range. Vertical thermoplastic sump pumps drain containment areas where spills and washdown collect. The system around the pump matters too: caustic lines in unheated spaces need freeze protection, which is a piping decision as much as a pump decision.
How RE Merrill confirms the selection
Concentration and temperature decide which materials and which pump architecture fit a caustic duty, and we confirm both against curated compatibility data and factory guidance before we quote. Send the duty: concentration, temperature, flow, head, whether the line is heat traced, and whether the service is transfer, feed, or sump, and we return a confirmed selection.
Related lines
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