Although not an actual cover grade in its own right, the anti-static (electrostatic dischargeability) properties of a conveyor belt are a major safety consideration in environments where dust created by the conveying of coal, grain, biomass, fertilizer or other potentially combustible elements is present. Strict conformity to Directive 2014/34/EU (also known as ‘ATEX 95’ or ‘the ATEX Equipment Directive’) is applicable to potentially explosive atmospheres of zones 20, 21 and 22 where combustible dust is present. Despite the claims of some manufacturers, not all rubber belts are sufficiently anti-static. However, a major advantage of Dunlop “Made in The Netherlands” belts is that they are all anti-static (ATEX 2014/34/EU) according to EN/ISO 284 international test methods. This means that they can be used in ATEX classified areas. Please be aware that ATEX risk assessments may require additional safety measures.
ATEX certification: It is not possible to obtain an ATEX certificate for a conveyor belt because belts are classified as a component. ATEX certification only applies to the whole conveyor. When sourcing conveyor belts for use in ATEX regulated areas it is very important to ask for a copy of a certificate provided by an appropriate independent testing authority such as the German Institute Dekra Exam GmBH.
ANTI-STATIC (ATEX) – STANDARDS & TESTING
The ATEX standard is designed to help prevent dust or gas explosions in industrial environments, including conveyor systems carrying cargo such as coal, grain, and fertilizers. Health and safety experts determine if there are areas or ‘zones’ in industrial locations where there may be a risk of explosions. These are then classified depending on the severity of the risk. As a result, all equipment installed in these zones is legally required to comply with international ATEX safety standards. Conveyor belts must be conductive and therefore comply with the EN/ISO 284 international standard for electrostatic properties. EN/ISO 284 demands that the surface of the belt must be electro-statically dischargeable to enable the belt to conduct an electrical load. A conveyor that complies with ATEX requirements means that the conveyor components will conduct the electrical load to earth via the metal framework of the conveyor. This prevents sparks that could cause an explosion.
The ISO 284 test is intended to ensure that the belt is sufficiently conductive to avoid the accumulation of electrical static charge which can be developed during its service use. The principle of the test is that the electric current of specified voltage is passed via electrodes through a suitably prepared test piece taken from the belt. The test prescribes the use of a contact agent (fluid) to ensure proper contact between the electrodes and the belt surface. The electrical resistance of the conveyor belt, when tested in accordance with this method, should not exceed the maximum resistance value of 300 MΩ.
IMPORTANT SAFETY ADVICE: Belts that have no rubber cover on either side (double-sided slider belts) will not be sufficiently conductive to meet the EN/ISO 284 standard in dry conditions and therefore should not be used in ATEX classified zones.