Overview
ISO 4195:2012 specifies requirements and test methods for the relative heat resistance of rubber conveyor-belt covers with a cover thickness of ≥ 4 mm. The standard defines how to measure changes in hardness, elongation at break and tensile strength after exposure to elevated temperatures and sets permissible variations to evaluate compliance. It is not applicable to light conveyor belts as defined in ISO 21183-1.
Key Topics
- Scope and applicability: Applies only to conveyor belts with covers ≥ 4 mm. Excludes light conveyor belts described in ISO 21183-1.
- Classification (belt classes):
- Class 1: resistance to test temperatures up to 100 °C
- Class 2: resistance to test temperatures up to 125 °C
- Class 3: resistance to test temperatures up to 150 °C
- Test principle: Measure properties before and after controlled heat exposure and express results as variations in hardness, elongation and tensile strength.
- Sample preparation and exposure:
- Cut a full-thickness sample of 400 mm × 400 mm from the belt center, at least 100 mm from the edges.
- Place the sample in an air oven (per ISO 188) for 7 days at the class-specific temperature (100 °C, 125 °C or 150 °C).
- Allow the sample to cool before preparing test pieces.
- Conditioning and test-piece preparation:
- Hardness test pieces: sample or removed covers, lightly buffed and left at maximum thickness; condition 24 h at (23 ± 2) °C and (50 ± 5) % RH (Atmosphere B per ISO 18573).
- Tensile/elongation test pieces: covers cut to (2 ± 0.2) mm thickness, buffed and conditioned 24 h under the same atmosphere.
- For textile carcass belts or tropical conditions, alternative conditioning atmospheres (A or C) may be used as specified.
- Measurement methods: Use ISO 48 for hardness and ISO 37 for tensile strength and elongation testing.
- Results and reporting: Record initial and post-exposure values, calculate variations, and include specified information in the test report (reference to ISO 4195, belt identification, class, test conditions, conditioning details, results and test date).
Applications
- Selection and verification of conveyor belts for high-temperature industrial processes where rubber cover performance under heat is critical.
- Quality control and acceptance testing by manufacturers and purchasers to ensure belts retain acceptable mechanical properties after heat exposure.
- Risk mitigation when conveying bulk materials that may raise belt temperatures or where prolonged heat contact is expected.
Related Standards
- ISO 37 - Rubber: determination of tensile stress–strain properties
- ISO 48 - Rubber: determination of hardness
- ISO 188 - Accelerated ageing and heat resistance tests
- ISO 18573 - Conveyor belts: test atmospheres and conditioning
- ISO 23529 - Rubber: procedures for preparing and conditioning test pieces
- ISO 21183-1 - Light conveyor belts (not covered by ISO 4195)
Keywords: ISO 4195, conveyor belts, heat resistance, rubber covers, test methods, hardness, elongation, tensile strength.
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