My advice concerns the tension power calculations.

All components of these calculations should be broken down to allow maximum flexibility to the engineer performing the analysis. The return strand should be treated with the same detail as the carrying strand, because in a two way conveyor the return strand is a carrying strand. Rolling resistance (seal and bearing) should be identified separately from the flex and shear resistances of the belt and material. The latter should include roll diameter factors, troughing angle factors (including 0 degrees- flat belt), conveyed material factors and visco-elastic factors for the various rubber and plastic compounds.

Additionally the equations should be generalized for use in non-conventional conveyors such as horizontally curving and high-angle (sandwich-type). You may find interesting my article entitled "Sandwich Belt High Angle Conveyors according to the Expanded Conveyor Technology" in Bulk Solids Handling Vol. 20, No. 1, January/March 2000. Particularly, pages 35 and 36 reformulate the resistance equations for broader application and accounting.

I hope my comments are helpful. Good luck in developing a new and better standard.

Joseph A. Dos santos, PE ■

Hello,

A new British Standard for Troughed Belt Conveyors could be seen as a message from the grave. None of the BSI's referred to have ever offered a comprehensive answer to a designer. Business was kept alive in the UK by the National Coal Board & since that outfit vanished the demand for conveyor designs in the UK has all but disappeared. Although I was a long serving conveyor designer it is difficult to argue against the demise of the business.

It was always necessary to refer to Canadian, German, Australian & US standards for specific issues which should have been included in the BSSs. Issues like belt flammability, diaphragm cracking & belt cleaning were conspicuously ignored by the BSI. Safety & environmental issues are far more important than power consumption & these former topics are not adequately addressed by the usual Standards. What is the problem with power anyway? We just had to work out an approximate figure with DIN or MHEA/CEMA; select the hardware adequate for that power requirement: build the gadget and run it. If the actual power was less than the calculated figure the Client was in the money. Contractors told him the difference would be taken up when his business expanded & everybody went away quite happy. Hardware sizes always prevented problems; if you were near the machinery limit go up a size; because you have to. It really isn't rocket science is it? Is there is any value in publishing a regurgitated compendium of the existing British Standards? There are few potential British buyers to cover the price of ink, let alone the overheads. Copious information is available from DIN, MHEA(wherever they are hiding out now), several manufacturers & Trans Tech Publications. Logging on to a few of the sites at bulk-online provides more insight than any National Conveyor Standard anywhere; and for nowt! ■