The benefits of cone valves are well established and they offer a useful option for overcoming discharge problems when the required outlet size is smaller than the critical arching dimension for the bulk material. However, the claim that they achieve mass flow must be qualified. This may be true for small bulk storage vessels, like some IBC’s, but whether a hopper mass flows or not is dependent upon the geometry and construction of the container walls in relation to the contact friction and internal friction of the bulk material. A detailed overview of an expert system chart for hopper design and selection of discharge methods is shown on www.ajax.co.uk. Technical publications are also available from the company on flow problems are their solutions.

Lyn Bates ■

It's perhaps important to point out that the three posts above are, of course, biased towards their respective companies. Daniel Ruble (of Matcon, NJ, USA), Lyn Bates (of AJAX Equipment Ltd., Bolton, UK) and Steve (I can only assume "Steve Miles" of ISL Ltd, Gloucestershire, UK) will all, naturally, point out the benefits of their own technology or expertise.

The most important thing is to remove all reasonable doubt by testing your own material using the actual equipment you intend to buy. Any materials-handling equipment supplier worth its salt will have facilities available for you to evaluate exactly how your material performs.

Visiting a potential supplier will also give you the chance to see what kind of company you're dealing with; its size, experience and references should all affect your decision.

Hope this helps,

Colin ■