Overview
ISO 1306:1995 - Rubber compounding ingredients - Carbon black (pelletized) - Determination of pour density describes a laboratory method for measuring the pour (apparent) density of pelletized carbon blacks used in the rubber industry. This fourth edition (1995) replaces the 1987 edition and provides a simple, repeatable procedure for quality control and material specification of pelletized carbon black.
Key topics and technical requirements
- Scope: Applies to all types of pelletized carbon blacks intended for rubber compounding.
- Principle: Weigh a fixed volume of pelletized carbon black and calculate apparent (pour) density from the measured mass and vessel volume.
- Apparatus:
- Cylindrical vessel, recommended capacity 1 000 cm3 (diameter ~100 mm ±10 mm) with a regular wall and no spout or deformation (other capacities such as 624 cm3 may be used if equivalence is demonstrated).
- Straight blade or spatula, at least 130 mm long.
- Balance accurate to 0.1 g.
- Procedure (summary):
- Tare the cylindrical vessel and pour carbon black vertically to a specified height (not exceeding 50 mm below the rim).
- Overfill to form a cone, level once with the blade held horizontal and touching the rim, then weigh vessel plus sample.
- Determine the mass of carbon black (to 1 g where applicable) and compute apparent density (Pap).
- Note: when using the specified 1 000 cm3 vessel, Pap in g/dm3 is numerically equal to the mass in grams.
- Performance characteristics:
- Repeatability (single operator): r ≈ 3 kg/m3 - differences greater than this between two tests by the same operator are suspect.
- Reproducibility (between laboratories): R ≈ 13 kg/m3 - larger differences between labs require investigation.
- Safety: Users must follow standard laboratory safety practices; the standard does not cover all safety aspects.
Applications and users
ISO 1306 is used for:
- Quality control and incoming inspection of pelletized carbon black shipments.
- Batch formulation and volume-to-mass conversions in rubber compounding.
- Supplier specifications, acceptance testing and comparative product evaluation.
Typical users:
- Carbon black manufacturers and suppliers
- Rubber compounders and tyre manufacturers
- QC and analytical laboratories
- Standards bodies and testing service providers
Related standards
- ISO 1124:1988 - Rubber compounding ingredients - Sampling procedures for deliveries of carbon black (referenced for sampling practice).
Keywords: ISO 1306, pour density, apparent density, pelletized carbon black, rubber compounding, quality control, laboratory method, pour density determination.
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