The friction factor for a bulk material depends on both the nature of the material and the surface that it is in contact. In the case of residential waste, this may be expected to vary because of the wide range of products disposed of. The only positive way to resolve this question is to carry our a few simple wall friction tests to find out whether, for the source under considerations, whether there is any appreciable scatter in the results, what the bounds of variation are, and whether a 'safe' value can be utiised based on a sufficient number of test to provide confidence that the findings offer embracing results.

To carry out such tests on such material requires a relatively large cell and long stroke to accomodate the lumps and provide and average of the mix. The Ajax wall friction tester is, as far as know, the only commercial machine of this offering these features, see www.ajax.co.uk. ■

Dear Mr. Terence

Maybe a late answer but hopingly not to late.

Lin Bates have not inform you about the availability of test equipment on the market.

In our laboratory program we have definitely a tester for measuring of friction, our tester

RO-200 MANUAL is very simple and accurate test equipment for friction of powder with metal, powder to powder and density.

Please open our website WWW.IPT-ONLINE.COM and see if you can use one of our equipments.

We invite you to follow our course of “QUALITY CONTROL AND POWDER TECHNOLOGY” in the first weak of November sat UNIVERSITY OF DELFT – NETHERLANDS. Please send us your full address and we will provide you with the course program.

Hoping to hear from you soon

Best regards

Dr. Ivan Peschl ■

"Residential waste, assume dry and bagged"

So the waste is still in the bags then?

How big are the bags, what are the bags made of?

Are the bags likely to split and empty the contents?

What is likely to be in the bags of residential waste?

My 'residential waste' is a very variable product.

I think a few more details would help. ■