Correct test water for salt spray corrosion test

Answer: No. The salt spray test chamber is a key equipment for simulating corrosion conditions in marine or industrial environments and used to detect the corrosion resistance of materials or products. To ensure the accuracy and reliability of the test results, the specified sodium chloride (NaCl) solution must be used, and tap water is strictly prohibited. The reasons are as follows:

1) The composition of tap water is complex and interferes with the test results

Tap water contains impurities such as calcium, magnesium, chloride ions, fluorides, minerals and even trace heavy metals. These components will react uncontrollably with the pure sodium chloride solution required for salt spray testing, resulting in: the corrosion rate deviates from the standard and cannot truly simulate the marine or industrial environment. The test repeatability is poor, and the results of the same product in different batches of tests vary greatly. Standard salt spray tests (such as ASTM B117, ISO 9227) clearly require the use of distilled water or deionized water to prepare the solution to ensure the purity of the ingredients.

2) Tap water may clog the spray system

Impurities in tap water (such as scale and particulate matter) will be deposited in the nozzle, pipes and heating system of the salt spray chamber, resulting in uneven atomization and substandard salt spray deposition. Equipment failure rate increases, increasing maintenance costs.

3) Affecting the concentration of the salt solution, resulting in test failure

Salt spray testing must strictly follow the concentration standard (such as 5% NaCl solution). Impurities in tap water will change the actual concentration of the solution, for example: calcium and magnesium ions react with sodium chloride to reduce the effective chloride ion concentration. Impurities may accelerate or slow down the corrosion rate, making the test lose its reference value.

4) International standards explicitly prohibit

All authoritative salt spray test standards (such as GB/T 10125, JIS Z 2371) stipulate that distilled water or deionized water must be used to prepare the solution. Using tap water is an illegal operation and the test report will not be recognized.

5) Long-term use of tap water will damage the equipment

Scale and corrosive impurities will shorten the life of the salt spray chamber, especially the precision parts (such as sensors, heaters), and the maintenance cost is much higher than the cost of purchasing distilled water.

Correct operation

Preparation of solution: Dissolve analytical grade sodium chloride in distilled water or deionized water, with a concentration accurate to 5±1%.

Regular maintenance: Clean the water tank and replace the nozzle to ensure that there are no impurities left.

Water quality testing: Test the water quality when necessary.

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