Hi Vivek Bharti,

There is a lot of huff and puff on this subject, a few Yankee rule-of-thumb formulae, and not much real understanding.

A vent is a pneumatic pressure relief device. What exactly are you trying to do?

1 - You can design a receiving bin which can operate without a vent. We do that with blow-tanks in a pneumatic handling system

2 - Are you looking for dust control? That changes your point of view entirely, and probably gets your mind thinking more accurately on what you are trying to achieve.

3 - With loading of powder you can overload the bin and cause it to burst open with surcharge pressure. We had a case of a lime bin bursting, causing lime powder to flood the whole area. I did not get a thorough debrief to identify the true cause of the incident. You can also get aeration in the bin reducing its bulk density, meaning that it does not accept its nominal volume until the air is allowed to perculate out of the product. But there we are talking about the aero-dynamic behaviour of product inside a bin.

4 - With sinter we shut off the slide gates venting back to the dust extraction system without any adverse effects.

5 - To ease pneumatic overpressure problems I provided a 100 mm vertical vent pipe several meters high back into the top of another closed vessel. You have to compress a lot of air to generate any real over-pressure in a silo. You can rarely do that simply by dumping porous granular product from a conveyor belt.

Go back to basic engineering principles, and think about it step by step, item by item - what engineering factors are you likely to be dealing with? There are many things to look at, not just a couple of rule-of-thumb formula variables.

Regards - Sgt John.Rz

http://au.groups.yahoo.com/group/bionicresearch ■