The test standard summaries are for general guidance only. Though believed to be accurate at the time of writing, this may change over time. So this information should not be used as a substitute for referring to a complete test standard, at an appropriate revision level.
Note: the terms salt spray, salt mist and salt fog are all in wide spread use within corrosion test standards. In this context they can be considered to be equivalent and interchangeable terms.
ASTM G85 annex A4
Sulphur dioxide (SO2) salt spray test, cyclic
Can be used to test the relative resistance to corrosion of product samples that are likely to encounter a combined SO2/salt spray/acid rain environment during their usual service life.
Test specimens are placed in an enclosed chamber, and exposed to 1 of 2 possible changing climate cycles. In either case, the exposure to salt spray may be salt water spray or synthetic sea water spray. The most appropriate test cycle and spray solutions are to be agreed between purchaser and seller.
The first climate cycle comprises of a continuous indirect spray of neutral (pH 6.5 to 7.2) salt water/synthetic seawater solution, which falls-out on to the specimens at a rate of 1.0 to 2.0ml/80cm²/hour. During this spraying, the chamber is dosed with SO2 gas at a rate of 35cm³/minute/m³ of chamber volume, for 1 hour in every 6 hours of spraying. The entire test cycle is at a constant chamber temperature of +35C. The number of cycle repeats and therefore the test duration is variable.
The second climate cycle comprises of 0.5 hours of continuous indirect spray of neutral (pH 6.5 to 7.2) salt water/synthetic seawater solution, which falls-out on to the specimens at a rate of 1.0 to 2.0ml/80cm²/hour. This is followed by 0.5 hours of dosing with SO2 gas at a rate of 35cm³/minute/m³ of chamber volume. This is followed by 2.0 hours of high humidity soak. The entire test cycle is at a constant chamber temperature of +35C. The number of cycle repeats and therefore the test duration is variable.
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