Not if its only under the skirt seal area.

LKN ■

Dear Mr. Rubber,

Your belt conveyor actual speed is 30 m/min (0.5 mps). This is low speed and not very objectionable to the long skirt board mentioned by you. You can check for following options:

1) The belt conveyor should be of trough type and not flat.

2) Idlers spacing should be very close say around 250 mm to 300 mm.

3) Adequate tension should be imparted into the belt so that the belt sag percentage in conjunction with idler spacing create minimum gap (mm) for leakage. Increase the tension if allowed as per conveyor design or redesign the conveyor.

4) The specific tension in the belt should be created by using hydraulic tensioner while setting the screw take-up. This is very important.

5) The creation of belt tension simply by operator’s judgement and feel is not reliable. It should be by gauges.

6) The carrying idlers should be well aligned vertically as well as horizontally so that belt is in true straight line without ups and downs.

7) What is the material height in your hopper? If the height is abnormally high, it can promote the leakage due to material pressure. Maintain lower height of material.

8) Use wider belt and narrow skirt boards so that leaked material will be conveyed forward at discharge pulley instead of getting spilled.

Possible you are choke feeding the conveyor.

Hope the information will be of help to you.

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 ■

Hello there

I personally hate long skirts. The invariably look horrible and cause damage to the belt. If you must have them then make sure that:

-the loading chute forms a narrow steam of material in the centre of the belt

- there is a continuous wear plate each side containing the material and protecting the rubber skirts from wear

- The wear plate tapers out and away slightly from the belt to avoid trapping the material against the belt. (Other wise use plates only at loading points if too long)

- There are the slide plates as you call them where you get belt sag. This is very important to avoid material being trapped against the skirt plate and the belt as it goes over the idlers

- That sag is kept to a minmum

- The rubber skirt is for dust sealing only and is of the type that follows a saging belt..i.e. Brelco or equal

- (and that the belt tracks well)

Next time use a wider belt on steeper idlers. 750mm is narrow

Regards ■

As Mr. Mulani has indicated, it sounds as if your problem of spillage is directly related to the belt sag issue. His design options are appropriate, given the information provided.

As far as using UHMWpe slider bars are concerned, these work well if the belt is properly tensioned and does not bear heavily on them. If they are in constant contact with the belt, you will experience rapid wear of the polyethylene and some wear of the belt. As Mr. Nordell has indicated, these are a good option in load zones where they are normally placed slightly low so that the belt does not ride on them when empty. If you decide to use slider supports for the length of the system, you are essentially turning your trough conveyor into a troughed slider bed system. As such, the belt should then be changed to one suitable for slider applications - id est with a fabric backing.

Regards, ■

Dear Mr. Rubber,

The reasons for spillage may be numerous.

You mentionned saging of belt, which really is very often a big problem, because there is no skirting system existing, which can adapt to the wavy shape of a belt running over the idlers. Even shorter distances of the idlers is not solving completely the problem and who like to think about costs for 43m of additional idlers.

What I recommend are slide bars just under a skirting system and perhaps additional impact bars in the load zone.

But please do not use a normal vertical skirting rubber. I recommend a two-lip skirting rubber as shown in the excerpt of our book attached.

But before installing a new skirting system take care, that the belt is not mistracking because of the loading. If loading is not centralized the belt is wandering and spillage is to expect in most cases. maby you have to mistrack the belt before loading by purpose, so that loading will be centralized.

There are so many aspects in this manner, which are not possible to mention here.

Please feel free to ask me for more details, I am more than happy to help you.

with best regards

Attachments

ch09 - edge sealing systems (ZIP)

■

Dear Rubber

With sagging between the idlers and with such a long loading skirting length,you might like to provide a segmented type skirtboard sealing system like Tega design which can be installed as per the contour of the belt. ■

Consider using 5 roll idler sets with 35 deg & 70 deg wings, to create a U shape trough. The aim is to get the material away from the skirt & make it more difficult to the material to escape. ■