Along with effective extraction at generation source; clean, safe and healthy working environment for better productivity, effective filtration of these smoke/ fumes is also necessary.
No industry or project moves forward without processes like Welding, Soldering, Plasma cutting and/or laser cutting, etc. However, while doing so it generates an unwanted by-product - smoke. Many times acetylenes, argon or CO2, LPG are used for effective results as well as flux and special coatings on electrode wires, etc., which give fume that are by nature health hazards. Accordingly, in heavy-duty and mass scale welding and such other process shop, effective smoke/fumes extraction and filtration system becomes "must" from safety of the operator point of view. The general and normal logical way is to provide exhaust fans on sidewalls of the shop. But it is found that the same is just eyewash as the concentration of smoke/fumes at operating level (breathing zone) remains high because the density of smoke/fumes is much higher than normal air.
Hence smoke/fumes extraction from generation source with proper suction hood and suction velocity will give more effective results in controlling the same. However, along with effective extraction at generation source; clean, safe and healthy working environment for better productivity, effective filtration of these smoke/ fumes is also necessary. Since the smoke/fumes are of fine sub micron particulates matter filtration of it by any conventional mesh type filters is practically not possible unless paper base cartridge filters are considered. However, such filtration systems need high power consumption and regular cartridge replacement recurring cost.
A better techno-economical solution would be electro-static smoke/fumes precipitator technology. In this, fine sub- micron particulates are electro-statically charged by high voltage power-supply and then these are attracted and precipitated on opposite charged electrode plates that give back clean smoke/fumes free healthy air. It requires hardly 35- 40% power as compared to cartridge type filtration and has no recurring cost over lifetime of the equipment, i.e., 15-20 years. Depending on specific application, location, operational layout, etc., various models of electro-static smoke/ fumes collectors would be adapted for effective cost advantage and performance requirements.
Portable Weld-smoke Collector Unit
It is a lightweight portable unit that can be taken to nearby location where welding is done. With flexible suction pipe and magnetic base suction hood the smoke/fumes are effectively captured from generation source itself. The fine sub micron particulates are trapped in electro-static filter and clean air is then released back into working zone.
Localised Welding Booths/ Stations
When welding is done within a booth/station, the higher capacity unit with single \ double semi-rigid metallic suction pipe and fixed hood would be installed side wise as shown in the photograph. Depending on duty cycle and smoke/fumes generation, 2-3 welding stations would be clubbed together as one unit.
Centralised Welding Line
When there is a continuous line of welding operations like motorcycle/ scooter frame welding, auto-components welding line, etc, centralised fumes extraction from in-line locations and higher capacity single filtration blower unit becomes cost effective solution. Further, use of desert cooling pads with water spray gives comfort cooling effect to the air which can be supplied back to operators gives much better productivity in summer/hot season.
At places where big size/heavy and/ or complicated size jobs have a number of welders working, it becomes very difficult to extract the smoke/fumes from generation source. Boiler-shells, tankers, containers, tractors/earth moving equipment frame building, shipbuilding, etc., are some of the typical welding and fabrication shops, where above discussed methods cannot be adapted. In such cases effective dilution ventilation system by recycling shop air through open filters and adding fresh clean air to shop 25 to 30 times shop volume per hour will be effective to maintain the safe environment in working zone. By adapting any of the above-mentioned suitable methods, better indoor air quality would be achieved as per standard norms of ISO 9000/14000 and the Final results would be much better productivity and savings on house keeping cost.
|Posted : 8/12/2005|