Overview
ISO 3284:1974 specifies the dimensions of bends (elbows) used in pneumatic handling systems for loose bulk materials. Published by ISO/TC 101 (Continuous mechanical handling equipment), the standard defines geometric parameters for pipe bends in three duty series - light, moderate and heavy - and gives tabulated dimensions (in millimetres) for small, medium and large curvature options. The document supports consistent design, manufacture and interchangeability of pneumatic conveying elbows for bulk material handling.
Key topics and requirements
- Scope: Dimensions of bends for pneumatic handling of loose bulk materials for three service series (light, medium, heavy).
- Geometric symbols and parameters:
- D = inner diameter
- R = mean radius of curvature
- Dl = outer diameter of the pipe
- L = length of straight sleeve (manchette droite)
- Curvature classes: Small, medium and large curvature options are tabulated for each duty series.
- Dimensional tables: Provide specific D, Dl, R and L values (dimensions in millimetres). Typical table entries include diameters and radii across a practical range (examples in the standard span diameters from about 48.3 mm up to about 355.6 mm).
- Manufacturing notes: Recommended elementary arc segments are 15°, 22.5° and 30°, normally produced in moulded materials.
- Series usage notes: Some small-curvature bends are permitted for use in the medium series; priority series are identified in the original tables.
Applications and who uses it
ISO 3284 is intended for professionals involved in the design, manufacture, installation and procurement of pneumatic conveying systems for bulk solids:
- Mechanical and piping designers specifying elbows for pneumatic conveyors.
- Original equipment manufacturers (OEMs) producing moulded elbows and fittings.
- Plant engineers and system integrators ensuring compatibility of pipeline components.
- Procurement and quality assurance teams standardizing purchases and verifying dimensions.
- Consultants and standards committees referencing established geometric requirements for system layout and performance.
Practical benefits include improved component interchangeability, simplified procurement, predictable flow behaviour at bends, and reduced fabrication ambiguity.
Related standards
ISO 3284 was developed by ISO/TC 101 (continuous mechanical handling). For complete system compliance, users commonly consult other ISO and industry standards covering pneumatic conveying system design, material properties and mechanical handling safety (refer to current ISO catalogues or national standards bodies for up-to-date cross-references).