SIST ISO 7119:1997 PDF

Overview

ISO 7119:1981 defines a practical, standardized method for calculating the drive power of screw conveyors used in continuous handling of loose bulk materials. It applies to screw conveyors operating in a horizontal or inclined position (up to ~20°) with a regular, controlled and continuous feed. The standard excludes special-purpose screws such as extracting, calibrating, mixing, moistening, steeply inclined (>20°) and vertical screws. ISO 7119 is intended for designers, OEMs and engineers who need reliable power calculation and conveyor sizing guidance for bulk-material handling systems.

Key topics and requirements

• Scope and applicability: horizontal and moderately inclined screw conveyors for continuous flow of bulk materials; exclusions listed above.
• Power component model: total shaft power is the sum of three terms:
  • PH – power required to progress (convey) the material,
  • PN – power to run the screw at no-load,
  • Pst – power due to inclination (lifting or lowering material).
  • Total power: P = PH + PN + Pst
• Capacity and flow: the standard gives a method to calculate volumetric and mass flow based on screw geometry (diameter, pitch), rotational speed and a trough-filling coefficient (p) that reflects the degree of filling.
• Empirical parameters: introduces the progress resistance coefficient (A) and provides guidance on typical ranges (A generally in the order of 2–4) and how material properties affect A and filling coefficient p.
• Typical filling-coefficient guidance: examples for common operating cases (e.g., p ≈ 0.45 for free-flowing, non-abrasive materials; p ≈ 0.3 for typical bulk materials; p ≈ 0.15 for heavy, very abrasive materials).
• Practical formulae and variables: symbols and units are defined (screw diameter, pitch, length, speed, bulk density, mass flow, lifting height, gravity, etc.).
• Informative annex: example values for bulk density and progress resistance coefficients for a range of materials to support selections.

Applications and users

• Bulk-material handling design in industries such as mining, aggregates, cement, food processing, agriculture, coal and chemicals.
• Mechanical engineers, conveyor designers, plant layout engineers, procurement/specification teams, and maintenance planners who need to:
  • size drives and gearboxes,
  • select motor ratings,
  • verify conveyor performance under expected loading and inclination,
  • estimate energy consumption for material transport.

Related standards

• ISO 2148 (nomenclature for continuous mechanical handling equipment) is referenced for terminology.
• ISO 7119 was developed by ISO/TC 101 and is based on FEM (European Mechanical Handling Confederation) Section II work.

Keywords: ISO 7119, screw conveyors, drive power calculation, continuous mechanical handling equipment, bulk materials, conveyor design, progress resistance coefficient, trough filling coefficient.