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Source Capture Hoods

Source Capture Hood
Source capture of pollutants using localized exhaust hoods is an economical and cost-effective means to control plant air quality. Nuisance dust, fumes, mist or smoke can be effectively captured and removed at the source with properly designed source capture hoods. Capturing the dirty air at the source minimizes the amount of air exhausted from the space which reduces the amount of make-up air required back into the space.

Common Industrial Exhaust Hoods


Exhaust hoods provided by SysTech are custom designed to fit the application. The size of the workspace envelope, worker access requirements, capture velocity, and airstream materials help determine the design airflow. Design considerations include mounting configuration, side shields for cross drafts, materials of construction, internal baffles, open area, and capture velocity.

BACKDRAFT HOOD

Backdraft hoods allow for a uniform capture velocity over a wide area and are applied where overhead access to the work surface is not allowable. Backdraft designs are frequently used for exhausting fumes from open tanks and operations where canopy designs impede overhead functions such as cranes or lifting apparatus. The size of the hood (s) and number of slots is predicated on materials being captured, temperature, capture velocity, and height of work surface. Applications frequently require side shields to minimize cross-draft air movement. Frequent multi-slot applications include open surface tanks, weld stations, push-pull open tank exhaust, and foundry shakeout. Single slotted hoods, sometimes called slotted lip exhaust hoods, can be curved to fit up to a barrel or tub for barrel filling applications.

CANOPY HOOD

Canopy hoods are located above the work surface when overhead access is permitted and where large volumes of exhaust airflow are needed for rising smoke and fume extraction. Heated airstreams such as those found in melting processes carry the fume upward into the hood. Hood design options include insert baffles, a central interior air distribution plate, downdraft air curtains on the hood perimeter, or a skirt comprised of flexible curtain material. Where required, complete housing will be built around the process and hood to encapsulate smoke and fume. Application examples are most hot processes, large work areas, oven door exhaust, melting furnace door exhaust, dip tanks, and pouring stations.

CONICAL HOOD

Conical hoods are usually connected to ductwork or flex hose and are available in other rectangular shapes with an angular face or flange on the hood inlet to aid capture efficiency. These are used on flexible fume exhaust arms but can be applied to stationary applications. Materials of construction include carbon steel, aluminum, stainless steel, PVC, and FRP. They are frequently used for point source fume and dust capture extraction such as welding, grinding, barrel and bag filling, and for chemical fumes in laboratories.

BENCHTOP HOOD

These are small bench mounted or tabletop hoods with a filtration section added. They are applied as individual workstations where they are used to encapsulate smaller operations that generate hard to capture smoke and particulate. They can be connected directly to an external duct system, either from the assembly’s back, top or bottom. If needed, they can have an integrally mounted exhaust fan. The inlet shroud can be metal or “see-thru” materials like Lexan. Air filter The efficiency of the air filter is based on the material being captured. We see these in small assembly operations involving soldering, jewelry polishing and buffing, dental laboratories, and sample box work.

Advantages of Custom Exhaust Hoods


  • Can be moveable or fixed in-place, requiring a minimal amount of space
  • Often, they can be attached to a flexible extraction arm so they can be easily maneuvered out of the way
  • Custom designed to maximize collection efficiency at a point source
  • Fit to process equipment layout for dust and fume removal
  • Can be added to an existing central dust or fume collection system if the exhaust fan has performance capacity
  • Isolate pollutant points throughout a plant
  • Construction options of carbon steel, stainless steel, FRP or PVC

Poor Exhaust Hood Design


  • If the hood is not designed to be positioned close to the contaminant source it will not collect dust or fume effectively
  • When a hood is “not working”, it will not be used
  • If the hood design is “in the way” it will not be used
  • Room cross drafts, caused by local cooling fans or window fans, may push air away from the hood inlet and negate the effectiveness of source capture
We are familiar with many source capture hood applications requiring atypical designs and the necessary design steps needed for the proper collection of smoke, dust, and fume. Call us and see how we can help.

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