Yes, there are two concurrent solutions.

First and best use a curved loading chute -see our website. This will reduced the pressure on the skirtboards to an acceptable level or make the skirtboard redundant.

Second, you must take the pressure off the skirt rubber and this also assumes you have designed the proper idler support system at the loading impact area. To take the pressure off the skirt rubber you must have an inner chute liner/lip that keeps the product away from the rubber.

Want further help call us.

Lawrence Nordell

Conveyor Dynamics, Inc.

www.conveyor-dynamics.com

email: nordell@conveyor-dynamics.com ■

I agree with Larry Nordell that curved loading chutes are the ultimate. Absent that yo need to have good belt support, proper wear liner design and most of all preventiive maintenace to stop leakage at transfer points.

Visit our web site and look up BOCO Skirting. It is our latest system for sealing transfer points and it is self adjusting. www.martin-eng.com ■

I would suggest that detailed design attention be given to the transfer chutes on the following lines: -

1. - Collect, focus and guide the material via a chute that is based on the contact friction value of the material on the chute surface to a narrow flow channel terminating at a velocity similar to the receiving belt speed.

2. - Fit a flat skid plate under the belt at the recieving point, to avoid belt sag between rollers that tends to wedge fines under the skirt seal edges..

3. - Use diverging side skirts over the receiving area, so that the product is carried away from the seal points. A deep bed with wide diverging skirts will allow the bulk to stabalise over the initial belt run. Inclining the skirts away from the belt run, instead of being vertical, may also relieve transverse pressures of the material against the seal contact point.

I hope that these suggestions help.

Lyn Bates ■

Dear Sir,

Among othert good features, WEBA High-Tech transfers are designed to control material velocity and direction so that the load is transfered onto the outgoing belt without skirts. Check out their website at www.mjeng.co.za.

Joe Dos Santos, PE ■

Shri P K Kulkarni,

In general, there should not be objectionable leakage of material at skirt-board. Even if there is some leakage, the leaking material would be conveyed ahead between skirt-plate / rubber and troughed belt, without spillage or any problem. If the material is fine powdery, then air extraction and dust collection unit will prevent material fuming leakage. The main reason for leakage will be :

1) The belt tension under skirt board is not adequate. The belt tension shall be such that the belt sag between impact idlers (or other idlers at skirt board) should be less than 2.5mm, in any operating situation i.e. whether starting, stopping, steady; and capacity from zero to full mtph.

This value is at sag valley point. This point up/down level variation affecting sealing is likely to be less than 2mm. Sealing gap average value along length will be much less.

2) If the feeding point is located above sharply inclined portion of conveyor, the material will not pick-up speed quickly, resulting in material build-up height directly below feed chute, and consequent higher pressure and leakage.

3) The idlers should be spaced very closely 300 to 450 mm in accordance with belt tension.

4) The transition distance and belt profile should be such that the belt steadily rests on idlers all the time, and does not raise-up or lower.

Regards,

Ishwar G Mulani.

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

Email : parimul@pn2.vsnl.net.in ■