− BELT DESIGNATION −
Belts can be produced to various tensile specifications, using either polyamide (Nylon) or polyester base warp yarn. Some markets still prefer to specify belt types based on tensile strength expressed in lbs/in width (the Fenner Dunlop belt designation uses this term), whilst others opt for the preferred ISO nomenclature expressed in N/mm. The table below shows typical figures for minimum warp and weft strengths, belt thickness and weight for a selection of belt types, based on 1mm PVC covers. For thicker covers, add 1.3 kg/m2/mm for PVC covers and 1.4 kg/m2/mm for rubber covers, alternative constructions are available which give values higher than those in the table. This is particularly relevant to weft strength, where special yarns /designs may be recommended for improved properties such as fastener holding, load support and weft stability. The use of such special yarns may increase the belt weight and thickness which could be critical for shipping purposes or underground transportation. A Fenner Dunlop engineer should always be consulted where this is likely to be an issue.
− BELT THICKNESS −
When considering cover thickness, please be aware of the high textile content of Fenner Dunlop belting and the properties afforded by the increased carcass bulk compared to rubber plied belting. Consequently, thinner covers may generally be chosen than would normally be associated with an equivalent plied product, the enhanced textile density of Fenner Dunlop belting providing the necessary load support and resistance to impact.
− BELT WEIGHT −
Customers should be aware that lower belt weights may be advantageous on long conveyors as a means of reducing power consumption. High lift conveyors can incur a correction for slope tension which may be avoided by careful belt selection to minimise weight, resulting in considerable cost savings on certain applications, for example, drift conveyors.
− DRUM DIAMETERS −
The drum diameters quoted are the minimum generally recommended. Given specific information regarding wrap configurations, tensions, belt speeds, and jointing methods, it may be possible to recommend smaller drums.
− BELT STRETCH −
The unique design and manufacturing process of Fenner Dunlop belting allows both permanent and elastic stretch to be kept to a minimum, consistent with good operation. With numerous carcass designs available in both nylon and polyester yarns, it is impracticable to indicate all stretch figures. Further details can be provided on request.
− OPERATING FACTOR OF SAFETY −
With good quality mechanical fasteners or vulcanised joints a factor of safety of 10:1 is generally acceptable. However, we would be pleased to confirm the recommended belt construction and acceptable safety factor for any specific application on receipt of the necessary conveyor details. Customers are asked to specify their maximum acceptable roll diameters and weights so that Fenner Dunlop belts can be supplied in the most suitable roll lengths to avoid unnecessary joints. Fenner Dunlop belting can normally (subject to safe working limits in our factory) be produced in any required roll size to suit handling and transit to the site. Single or double coiled rolls can be supplied with fasteners fitted if required. Length tolerance is -0.5% +2% unless otherwise agreed. Short belts can be spliced into endless loops as part of the manufacturing process.
− OPERATING TEMPERATURE RANGE −
Above 90°C PVC softens and the belt properties change. Fenner Dunlop belting is therefore not recommended for conveying materials above this temperature. Standard Fenner Dunlop belting can be used in cold climates at minus 15°C although special cover compounds are available for operation down to minus 30°C. Where applicable, cold weather details should be supplied to ensure that belting with a suitable coefficient of friction and flexibility characteristics is specified.