The process
Fabrication shops capture welding fume at source with arms and hoods into cartridge filters, and clear the general shop air with roof extractors and wall fans.
The gas at the fan
Fine metallic fume from welding and cutting, captured at source and taken to a cartridge filter. Light dust, ambient temperature; the fan is sized for the hood capture velocities and the filter pressure drop.
Selection for this duty
| Blade form | Backward inclined or backward curved; the residual dust does not justify a radial wheel |
| Material of construction | Mild steel |
| Drive and bearings | Direct coupled or belt driven; belt drive where the duty point may need tuning at site |
| Density at the fan | At about 35°C the gas density is close to 1.15 kg/m³, 95% of standard air. Pressure developed and power drawn fall in the same ratio, so the selection is made at this density and the motor is checked at cold start. |
Hoods, ducting and an exhaust fan that capture fume at source and deliver it to a scrubber, bag filter or stack. Fan material follows the fume: stainless steel, PP-FRP or rubber lined where it is corrosive. Client-stated blade types for the Fume Exhaust System in general: Backward inclined and radial tipped.
Industries
Other fans in welding and fabrication shops
Fume Exhaust System in other processes
Coke Oven BatteriesElectric Arc Furnace SteelmakingInduction Furnace Melt ShopsLadle Furnaces and Secondary MetallurgyForge ShopsFerro Alloy Submerged Arc FurnacesAluminium Smelters and Cast HousesCopper and Zinc SmeltingIron and Non-ferrous FoundriesHot Dip Galvanising LinesChemical Reactor and Tank VentsEffluent Treatment and Zero Liquid Discharge PlantsSolvent Recovery PlantsFertilizer Granulation PlantsSulphuric Acid PlantsFood Ovens and FryersPaper Machine Dryer SectionsPulp Mills and Recovery BoilersTextile Stenters and DryersDyeing and Finishing HousesAutomotive Paint ShopsPickling and Acid Treatment LinesTyre Curing PressesShipyard Hull and Block Fabrication
Services on this fan
Information needed to select or quote
- Duty point. Volume flow and static pressure at the fan inlet, with the gas density and temperature or the conditions to derive it.
- Operating conditions. Site altitude, normal operating temperature and continuous or intermittent duty.
- Gas stream. Dust loading and particle size, corrosive species, moisture, upset temperature and any tendency of the material to deposit on the impeller.
- Mechanical. Rotation viewed from the drive end, discharge orientation and motor power.