Dear All,

I dont know whether this thread is still "live" but here is my view as a plant engineer in the food industry.

I have always relied upon the knowledge of the equipment suppliers to provide kit to meet my process requirements. If I go looking for a car I don't expect to have to know all the details about how the engine is designed - similarly if I need process equipment I rely on the suppliers to have the expertise! The knowledge for reliable equipment operation (i.e silos, etc) should reside with the equipment manufacturers / suppliers.

Quite how they obtain their knowledge (whether through trial and error or from technical papers) is their responsibility.

Yours

E. Quill ■

Many problems arise with solids handling plant for the reasons given by Peter Brown. Earnie Quill puts forward the reasonable case, which I agree with, that the supplier should be relied on to provide the specialised knowledge. However, the problems posed by Peter indicate the gulf that often exists between user and supplier on the degree and quality of information that is required to prepare a fair and equitable contract for a given duty. Efforts made to bridge this gap include the I.Mech.E ‘guide to the Specification of Bulk Solids for Storage and Handling Equipment’, The British Materials Handling Board ‘Guidelines for Specifying Weighfeeder Systems’ and the SHAPA publication, ‘The Surface Finish of Stainless Steel’.

There is a need to establish technical rapport between the end user and the supplier of solids handling equipment. This can be impeded by main contractors, sub-contracting situations, and sometimes by intransigent buyers concerned only with price, particularly if other suppliers adopt a more cavalier attitude to guarantees. ‘Caveat Emptor’ not only applies to suspicions of a suppliers motives but, in these cases, pertains to the fact that it is virtually impossible to insulate the user from serious liabilities should to performance of the equipment go catastrophically wrong.

A responsible supplier should ferret into any information gap, even against resistance, because it is to the mutual interest of both parties to ensure reliable performance. If data is not available for any reason, then this should be brought out and the implications allowed for by agreement prior to order placement.

It is also the responsibility of industry to interpret scientific research and present this in the form of developments and innovative equipment to users. For examples of this and attempts to present technical information to users, see the Ajax web site – www.ajax.co.uk.

It is often difficult to convince users to spend money on powder testing for apparently simple and relatively low capital cost items, such as chutes, transfer points and small hoppers. The importance of such items for reliable performance has no relation to their cost. Attention can only be drawn to the effects of difficulties and consequences of their failure. As for buying at the cheapest price, our advice to Un-enlightened Buyers of Solids Handling Equipment is given in the following extract from our series of ‘Ten Key Steps for Good Performance in Solids Handling Plant’

1. Do not give the supplier any information about the bulk material. Show him a sample that you have obtained from the floor or nearest rejection bin. This will test his ability to find out what the material is really like in practice, and he should be a clairvoyant anyway. The real benefit though, is that you cannot be held responsible when the plant doesn't work.

2 NEVER call in a consultant. People might come to think that you do not know your job. He will cost you hard cash now. Any lost production and increased manufacturing costs will fall some time in the future, and can be blamed on others, if your still around.

3Do not compromise the bin holding capacity with minor details, such as steep wall angles for slip or large outlet size for reliable flow. Any fool knows that most materials will slide down a 45 degree inclined surface and the hole must be bigger than the largest lump. And after all, it is the operator’s job to get the material out, so why should you worry?

4Buy the cheapest kit. That's the way to save money on capital goods. Higher revenue costs come from another pocket and will always be accepted as an inevitable ongoing expense.

5 Do not read technical literature about the state of the art. It's specialised and not all that simple. Your concern is what the plant has to do, not how it is done. It's not your job to design kit. Let someone else worry about that, and take the responsibility.

6Make sure that you have a good lawyer. He will not make your plant work, but you may have the satisfaction that the equipment supplier will get a good pasting, if your guy is able to make some stiff penalty clauses stick.

7Specify thick plates on the bin, and weld some heavy steel sections near the outlet, so that it can be hammered without causing too much damage. Buy ear plugs for operators.



8 Collect leaflets for vibrators, air cannons, sledgehammers and other flow-promoting devices. You'll need them, or note Ajax's fax, phone and Email address for retrofits.

9Get well equipped with overalls, dust masks, goggles, long boots, gloves, a big shovel and a long pole. Revise your production schedule to be more 'elastic', and cancel your holidays.



10 Study acting, your day job does not look all that secure.

Lyn Bates ■