Handling The Heat

Nothing destroys a rubber conveyor belt faster than heat. It is a common misconception that all heat-resistant conveyor belts of a stated specification should provide a similar performance and operational lifetime. In reality, alarming differences are commonplace. However, before looking at the reasons for such differences, it is perhaps a good idea to first clarify the different specifications applicable to heat-resistant conveyor belts and the associated terminology.

The temperature limits that a belt can withstand are viewed in two ways – the maximum continuous temperature of the conveyed material and the maximum temporary peak temperature. Heat-resistant grades are historically identified as grade ‘T’. The international ISO 4195 specifies the requirements for heat-resistant belt covers, which spans classes 1, 2, and 3. The two identifications are commonly combined into classes T1, T2, and T3 respectively, although some use T100, T150, and T200 instead. The most important thing to remember is that there are only two main classifications of heat resistance recognised in the market. These are T150, which relates to a maximum continuous temperature of 150°C and T200, which is for more extreme heat conditions up to 200°C.

Continuous and peak temperatures

The difference between continuous temperatures and peak temperatures is a critical issue and is the most common cause of warranty disputes. For example, although a belt classified as T150 should consistently withstand continuous material temperatures up to a maximum of 150°C over long periods, it can only cope with peak temperatures in excess of that limit for a very short period of time (literally minutes). The same principle applies to the T200 classification for peak temperatures higher than 200°C. Any period longer than just a few minutes will almost certainly cause irreparable damage to the belt.

To provide a working example of what this means, at Dunlop the ISO 4195 class 2, or T150, belt is Betahete, which is designed for materials at continuous temperatures up to 160°C and peak temperatures as high as 180°C. For ISO 4195 class 3, or T200, there is Dunlop Deltahete, which is engineered to withstand maximum continuous material temperatures as high as 200°C and extreme peak temperatures as high as 400°C.

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