Overview - ISO 8397:1988 (Test sieving for solid fertilizers and soil conditioners)
ISO 8397:1988 specifies a laboratory method for determining particle size distribution of solid fertilizers and soil conditioners by mechanical dry test sieving. The standard defines the procedure for dry sieving one or more test sieves using a mechanical sieve shaker, describes required apparatus and sample preparation, and sets criteria for reporting and for the statistical fidelity of results (repeatability and reproducibility). The method has been validated for sieve openings in the nominal range from about 100 µm to 5.60 mm.
Key topics and technical requirements
- Scope and principle: Mechanical dry sieving of an accurately weighed test portion through a stack of sieves to obtain the mass of material retained by each sieve and the pan (tamisat).
- Apparatus:
- Analytical balance with 0.1 g precision.
- Test sieves: 200 mm diameter stainless-steel woven wire sieves conforming to ISO 3310‑1.
- Mechanical sieve shaker capable of horizontal and vertical motion.
- Stopwatch and a soft round brush for clearing meshes.
- Sample preparation and quantities: The standard provides recommended sample masses/volumes relative to the dominant fraction and sieve opening (see its Table 1). Sample reduction methods are referenced and two independent test portions are required per laboratory.
- Procedure:
- Select up to seven sieves in ascending mesh size.
- Assemble, weigh the test portion to 0.1 g, sieve for 10 minutes, then collect and weigh retained fractions and pan.
- Clean mesh surfaces by brushing before weighing.
- Results and statistics:
- Express each retained mass as a percentage of total test portion.
- ISO 8397 gives statistical limits for repeatability (r) and reproducibility (R); empirical maximums cited are about 2.5% (r) and 12.5% (R) for typical fractions. Example fidelity data are provided.
- Test report requirements: Must include method reference (ISO 8397), sample identification, nominal sieve openings used, masses retained, mean percentage retained per sieve, and any operational details or incidents.
Applications and users
ISO 8397 is used for sieve analysis and granulometric characterization in:
- Fertilizer and soil conditioner quality control laboratories
- Production and R&D teams in fertilizer manufacturing
- Agricultural laboratories validating product compliance with specifications
- Third‑party testing and certification bodies
Keywords: ISO 8397, test sieving, solid fertilizers, soil conditioners, particle size distribution, sieve analysis, granulometric analysis, mechanical sieve shaker.
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