Selecting dust suitable for a dust test chamber requires considering the test standard, dust characteristics, and test objectives to ensure accurate and comparable test results. The key steps and key points are as follows:
1. Prioritize compliance with test standard requirements
- Identify the specified dust type based on the product's corresponding international/industry standards (such as IEC 60529, ISO 12103, GB/T 4208, etc.).
- Most Common Standards: Almost all common standards require the use of ISO 12103-1 Grade A2 talc powder (test dust A2), which is the "reference dust" for dust testing.
- Special Industries: Some sectors (such as automotive parts) may specify equivalent dusts (such as Grade A1 or specific mineral powders), but their particle size distribution must be consistent with Grade A2.
2. Examining Core Dust Characteristics
Particle Size Distribution
- At least 90% of the particles must be between 1 and 85 μm in diameter, with the largest particle size not exceeding 150 μm (to avoid clogging the equipment or failing to simulate natural dust infiltration).
- Can be verified by sieving or laser particle size analysis.
Purity and Impurities
- Must be clean and free of impurities (such as fibers, metal shavings, and salt) to prevent impurities from causing additional corrosion or damage to the test sample.
Moisture Content
- Must be ≤ 0.1% (mass fraction). Moisture-caked dust must be dried before use (at 105°C ± 2°C to constant weight), otherwise dispersion uniformity will be affected.
Physical Stability
- Particles must be inert (not chemically reactive with the sample) and nearly spherical in shape to prevent sharp particles from scratching the sample surface.
3.Adjustments Based on Test Purpose
- For routine quality testing, standard A2 grade talc powder can be used directly.
- To simulate a specific environment (such as high dust concentrations in desert areas), dust with a particle distribution closer to the target environment may be selected based on the standard (this must be specified in the test plan in advance).
4. Select Compliant Suppliers
- Prioritize purchasing certified standard dust (e.g., branded products compliant with ISO 12103-1) to avoid parameter deviations caused by custom configuration.
In summary, the core selection principles are: "standards first, parameter matching, and qualified status" to ensure that the dust truly simulates the dust control challenges your product will face in the natural environment.
