Salt spray test chambers have strict standards for water and salt water, which directly determine the reliability of the results and the lifespan of the equipment.
I. Test Water (Required)
✅ Qualified Water (Choose one)
- Deionized water/Distilled water (Preferred)
- Conductivity: ≤20μS/cm (Grade I water ≤5μS/cm is more stable)
- Total dissolved solids (TDS): <200ppm
- Free of calcium, magnesium, iron, chloride, carbonate, and other impurities
- Grade II deionized water (when conditions are limited)
- Conductivity ≤10μS/cm, requires filtration to remove particulate matter
❌ Absolutely prohibited
- Tap water, well water, mineral water (contains minerals, causes scaling, nozzle clogging, and interferes with corrosion)
- Purified water/bottled water (conductivity often exceeds the standard, unstable)
II. Test Salt Water (Prepared according to standard)
1. Salt Requirements
- Reagent: Analytical grade sodium chloride (NaCl)
- Purity: ≥99.5%
- Impurities: Free of iodine, copper, nickel, calcium, and magnesium (sodium iodide <0.1%)
2. Three Standard Salt Spray Formulas (GB/T 10125 / ISO 9227 / ASTM B117)
① Neutral Salt Spray (NSS, most commonly used)
- Concentration: 5%±1% (50g/L) (50g NaCl + 950mL deionized water)
- pH: 6.5-7.2 (25℃)
- Temperature: 35℃
- Application: General corrosion resistance testing for metals, coatings, and electroplated parts
② Acetic Acid Salt Spray (ASS)
- Concentration: 5% NaCl
- pH: 3.1-3.3 (adjusted with glacial acetic acid)
- Temperature: 35℃
- Application: Aluminum anodizing, decorative coatings, simulated acid rain
③ Copper Accelerated Acetic Acid Salt Spray (CASS)
- Concentration: 5% NaCl + 0.26 g/L Copper Chloride (CuCl₂·2H₂O)
- pH: 3.1-3.3 (Glacial Acetic Acid)
- Temperature: 50℃
- Application: Rapid accelerated testing of nickel-chromium plating
III. Preparation and Usage Points
- Prepare and use immediately, consume within 24 hours to avoid deterioration
- Stir until completely dissolved and free of suspended matter
- Calibrate with a hydrometer: 1.038-1.042 at 25℃
- Clean the brine tank, nozzle, and pipeline regularly to prevent crystallization and clogging
IV. Quick Selection
- Conventional Metals/Coatings: NSS (5% NaCl, pH 6.5-7.2)
- Aluminum Oxidation/Decorative Coatings: ASS (5% NaCl, pH 3.1-3.3)
- Nickel-Chromium Rapid Testing: CASS (5% NaCl, pH 3.1-3.3) NaCl + CuCl₂ (pH 3.1-3.3)
