Overview
EN ISO 703:2025 - Conveyor belts: Transverse flexibility (troughability) - Test method defines a laboratory procedure to quantify the transverse flexibility (troughability) of conveyor belts. The result is reported as a dimensionless ratio F/L (vertical deflection corrected for belt thickness divided by flat width). This European adoption of ISO 703:2025 replaces EN ISO 703:2017 and is intended for standardizing conveyor belt testing across CEN members.
Key topics and technical requirements
- Scope: Measures troughability for conventional conveyor belts; not suitable for light conveyor belts referenced in ISO 21183‑1.
- Test principle: A transverse belt section (length L = full belt width) is suspended by its edges, allowed to sag under its own weight, and the maximum vertical deflection F is measured.
- Test piece dimensions: Longitudinal length = (150 ± 2) mm; thickness d is the overall belt thickness.
- Conditioning: Test pieces must be conditioned per ISO 18573 using atmosphere D or E immediately before testing (conditioning requirements were revised in this edition).
- Apparatus essentials: two rigid horizontal bars, two clamps that do not introduce bending moments, four equal-length suspension wires, and means to measure deflection to the nearest millimetre.
- Measurement and calculation: After 5 minutes in the troughed position, measure the vertical deflection F_measured and compute F = F_measured + 0.5·d. Report results as F/L.
- Reporting: Test report must identify belt, manufacturing date, reference to ISO 703:2025, L, d, conditioning atmosphere (D or E) and the F/L result.
- Limitations: The measured “flexibility” is only indirectly related to flexural modulus (ISO 178) and does not distinguish between three‑ and four‑point bending behaviours.
Applications and users
- Who uses it: conveyor belt manufacturers, independent testing laboratories, OEMs, conveyor designers, maintenance and reliability engineers, procurement and quality assurance teams, and certification bodies.
- Practical value:
- Select belts compatible with troughing idler geometry and reduce lateral travel/track problems.
- Establish acceptance, quality-control and comparative data for belt batches.
- Inform conveyor design decisions where trough shape stability and empty-belt tracking are critical.
- Keywords: EN ISO 703:2025, conveyor belts, troughability, transverse flexibility, test method, F/L ratio, belt conditioning, conveyor belt testing.
Related standards
- ISO 18573 - Test atmospheres and conditioning periods
- ISO 583 / ISO 7590 - Methods for thickness measurement (textile/steel-cord belts)
- ISO 178 - Flexural modulus (related but not equivalent)
- ISO 21183‑1 - Light conveyor belts (method not applicable)
This standard gives objective, repeatable data for troughability, helping ensure belt performance and compatibility with conveyor systems.