ISO 284 Conveyor Belts - Electrical Conductivity - Properties and Test Method

The ISO 284 Conveyor belts - Electrical conductivity - Properties and test method standard, published by the International Organization for Standardization (ISO), describes the maximum electrical resistance of a conveyor belt and the relevant test method. This test method aims to ensure that the belt is sufficiently conductive to prevent the accumulation of electrical static charge that may occur during use. This standard is not suitable or applicable to lightweight conveyor belts, the static electrical properties of which are measured by ISO 21178, as described in ISO 21183-1.

In principle, when tested according to this standard, the electrical resistance of the conveyor belt should not exceed 3 x 108⁸ Ω (300 MΩ). Lower values ​​may be specified for special applications. During testing, an electrical current at the specified voltage is passed through electrodes to a suitably prepared test piece taken from the belt.

The test piece must be square and cut to the full thickness of the belt. The length of one side must be at least 300 mm. One test piece should be taken. If the specification requires two or more test pieces but does not specify how they should be selected, reference may be made to ISO 282. If applicable, both surfaces of the test piece are cleaned by rubbing with a clean cloth, for example, with Fuller's earth (i.e., hydrated magnesium aluminum silicate). After all traces of dust have been removed, the surface is wiped with a clean cloth moistened with distilled water, then dried with a clean cloth.

Before testing, the test piece is exposed for at least 2 hours to one of the standard laboratory atmospheres specified in the ISO 18573 standard. The test is then performed in this atmosphere. An atmosphere with a temperature of 23 degrees plus/minus 2 degrees and a relative humidity of 50 percent plus/minus 5 percent is preferred.

The following steps are followed when administering the test:

• The atmosphere of the test chamber is controlled.
• Contact gel is applied to one of the surfaces of the test piece, to the two areas shown in the figure. Great care must be taken to ensure the accuracy of the area dimensions, but symmetry of the center is not critical. If the surface of the test piece is flat, this gel can be applied to the underside of the cleaned electrodes. On textured surfaces, the two areas shown in the figure should be applied to the test piece. The test should be performed immediately after staining.

For covers with uneven surfaces, contact between the electrodes and the test piece can be improved by using thin layers of metal foil the same size as the brass electrodes. These layers are placed on top of the liquid contact material and gently rubbed with a finger to conform to the surface shape. Then, the brass electrodes are placed on the foil.

• The test piece is placed on the insulation material with the test surface facing upwards.
• The bottom surfaces of the brass electrodes are cleaned and they are placed in the liquid contact medium pattern on the test piece.
• Care should be taken not to breathe onto the test surface, as any moisture condensation can result in inaccurate readings.
• The external electrode is connected to the grounding or low voltage terminal of the measuring device.
• The inner electrode is connected to the high-voltage terminal of the measuring device.
• Resistance is measured after the voltage has been applied for at least one minute.
• This test is repeated on the other surface of the test piece.

The primary purpose of ISO 284, an international standard addressing safety issues in industrial conveyor systems, is to prevent the accumulation of static electricity, which can lead to dangerous sparks in hazardous environments.

Conveyor belts are widely used in industries such as mining, manufacturing, bulk material handling, and agriculture. During operation, friction between the belt and materials or rollers can generate static electricity. In environments where flammable gases, dust, or vapors are present (e.g., coal mines or grain silos), the accumulated static charge can ignite, causing explosions or fires.

To mitigate this risk, conveyor belts must be antistatic, meaning they must have sufficient electrical conductivity to safely dissipate static charges to the ground. The ISO 284 standard ensures that the belts meet a threshold value that is low enough to allow for charge discharge but practical for belt manufacturing.

This standard explicitly states that it applies to heavy-duty conveyor belts and is not suitable for light-duty conveyor belts (which are covered by standards such as ISO 21178 and ISO 21183-1).

The basic specification is the maximum electrical resistance: The surface resistance of the belt must not exceed a defined limit (typically in the range of 300 megaohms or lower, depending on the version and application). Exact values ​​are detailed in the standard document. This ensures that the belt is conductive enough to prevent the accumulation of electrical static charge that may occur during service use.

The ISO 284 standard defines a precise laboratory test:

• Samples are cut from the conveyor belt.
• Electrodes are applied to the surface or across the thickness of the band to measure resistance.
• To obtain reproducible results, conditions such as temperature and humidity are controlled.
• The setup involves applying a voltage to calculate the resistance and measuring the current.

This method verifies compliance during production and quality control.

Compliance with the ISO 284 standard is often mandatory, especially in high-risk sectors such as underground mining or explosive environments. This standard complements other conveyor belt standards such as fire resistance or mechanical properties.

Many national standards directly adopt the ISO 284 standard. Manufacturers test tapes according to this standard to certify them as antistatic.

In conclusion, the ISO 284 standard plays a critical role in industrial safety by standardizing the antistatic properties of conveyor belts. Its continuous updates reflect the importance of preventing static-related hazards in modern operations. All technical details, including precise resistance limits and test procedures, are included within this standard. For those involved in conveyor system design, procurement, or safety compliance, adhering to the ISO 284 standard reduces the risks associated with electrostatic discharge.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its customers, providing the advanced testing services they require, and assisting in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services to businesses in accordance with the "ISO 284 Conveyor belts - Electrical conductivity - Properties and test method" standard.