Dear Shri Suresh,

The basic need for belt weigher to give correct indication is that the gravity force on belt and material should only impose force on the load cell system. So, belt weigher should not be installed in convex / concave curvature wherein fluctuation in belt tension will affect the forces coming on load cell.

Regarding belt weigher installed in a belt conveyor equipped with screw take-up, primarily there does not appear any objection. However, if the belt has become somewhat loose and it is not tightened by screw, then, belt sag will be excessive along with more turbulence in material on belt. This could create marginal fluctuation in the forces coming on load cell. The belt conveyor equipped with automatic gravity take-up will ensure specific belt tension all the time and thereby there will be less possibility of such unwanted variations.

As I said earlier, the installation of belt weigher on conveyor equipped with screw take-up is not a totally unacceptable situation, so long as it is not in the curvature zone.

Regards,

Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyors.

Advisor / Consultant for Bulk Material Handling System & Issues.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 25882916 ■

Dear Mr. Suresh,

I do not find any reason. You can install belt scale in conveyor having screw take-up.Many installation we have in INDIA. You know all WEIGH FEEDERS are having screw take-up arrangement. They are working well with good acuracy.So please go-ahead.

Regards.

A.Banerjee ■

Weigh feeders with screw TU are not ideal wrt accuracy, we prefer GTU (and auto belt tracking) weighfeeders and am looking to convert the others.

The way to test this is from stocks comparison at the end of each month rather than live load calibrations.ie truck dump

If U have weigh scales on screw TU belts, suggest a re - zeroing function check regularly and/or some means of checking belt tension eg Beville washers.

Cheers

James ■

Gentlemen,

As previously posted, a belt scale will work on a conveyor with a screw take up. I feel it is worth mentioning that changes in temperature will effect the performance of the scale to a greater extent on systems without a gravity take-up.

As per the rules governing certified belt scales in the United States, a conveyor without a gravity take-up can not be used as a certified scale system, as defined in NIST Handbook 44. Part of the discussion would then be, what type of accuracy are you trying to achieve? ■