Hoods for Collection
US Duct is uniquely qualified to combine experience in solving various collection problems with years of metal fabrications experience to assist customers in designing suction hoods.
PROBLEM: It is very common for a collection system to involve a unique situation involving anything from a specifically designed machine, an unusual work flow process, a unique dust or a combination of all of the above.
SOLUTION: US Duct personnel work with you to understand ALL of the dynamics of the application and then fabricate a solution. They can show you a wide variety of past solutions and draw you (in 3D) proposed solutions. And then they can produce them for you at a reasonable price.
Suction hoods are an essential part of virtually every collection system. The objective is to design a hood that is able to capture the fugitive dust or fume, at a velocity that will 'pull' it away from its normal trajectory, and from a distance that is suitable to the application. For example, a hood on a dump bin must be able to capture dust that spews up from the dumping while not being so aggressive as to pull the material that is being dumped. Likewise, a router hood must be able to capture flying wood chip while not being in the way of the work space.
These examples highlight the complexity of designing a hood and the futility of just building a 'box'.
Proper design begins with understanding the dust, it's characteristics and the velocities at which it can be conveyed. It continues on to the understanding of the work process- is the duct floating, or being propelled by and action. And it must consider other things like; What is generating the dust/fume? Where is the operator if there is one?
It is important also to understand the dynamics of air. For example- most people think that suction occurs equally across the face of a hood. For example: given a 4" x12" hood (or any size) they would think that the air is coming equally at all points along the 48 square inch face. And they would expect it to dimension equally the further you are from the face. But air is a liquid and does not function that way. To help understand this consider a hood as being like the opening of a 5 gallon bucket. As you lower the bucket into a deep pool, you notice that the water is flowing around the edges first. Even if you quickly submerge the bucket, the water comes in from the side. Yes these dynamics are related to the fact that the bucket is surrounded only on the sides by the water and it is not meant to be a demonstration of all the actual physics, but it is actually a very good picture of what takes place with a hood. As the vacuum is created by the suction, the air that is going to fill the void, will first come in from the sides of the hood. In fact, the strongest point of suction on a straight hood (no flange) is on the outside of the hood and just behind the edge. Prove it to yourself using a cigarette and a hood. The ability of a hood to 'reach out' can therefor be dramatically increased by adding a right angle flange to the edges of a hood. This prevents the air from 'lipping' around the sides.
US Duct assist their customers by getting a full understanding of the work process, the generation of the dust, the dust, the collector and the air available. They then can assist in the design, pointing to previous fabrications and finally- creating a 3D drawing of the proposed solution.