Matt,

A bypass chute in the hopper section of a mass flow bin will generate additional stresses because of changes in the velocity profile and creating eccentric flow patterns. If this bypass is needed, it will be much better to install it in the vertical section of the bin, a few feet above the transition. In this location, wall stresses are not as high as they are in the hopper section, thus requiring much less additional steel.

Regards,

A. T. Agarwal

Pneumatic Conveying Consulting Services

polypcc@aol.com

Ph and Fax: 304 346 5125 ■

From the information given it would appear that the by pass chute has been used for some time, presumably without obvious problems, so the questions this raises are - how does the contracter wish to alter it and will this give rise to difficulties that were not previously experienced?

Provided that there is not a major enlargement of the connection to the silo cone it would seem that any external alteration would not make a material change to the internal flow regimes in the contents. It would be useful to know the precise nature of the changes proposed, have dimensional details of the silo cone and knowledge of the contents in order to give a more considered opinion.

The photograph seems to show a relatively small pipe simply connected to the sloping wall of a cone, so the product stored must be fairly free flowing. One way to avoid ecentric stresses is to project the pipe into the centre of the silo cone, but be sure to rib the underside to support it against the flow pressures that develop when the bottom outlet is being used. ■