African Fusion June 2015

Envirox: Fume extraction systems

AfricanFusion visits theElandsfontein facilities of Envirox, the SouthAfricandistributor of Nedeman’s range of fume extraction systems, hoods and extraction arms and talks to Schalk Hoon (left), the company’s general manager and Anton Herteberger (right), business development manager. Fume extraction:

“ W here most people will put large hoods above a welding bay, we prefer to extract welding fume at source, where the welding is happening, so that no fume goes anywhere near the welders face,” begins Hoon. To do this, Neder- man offers the most comprehensive range of fume extraction arms to ensure that the extraction point is always less than 500 mm from the point of welding. “All possibilities are covered. We offer mobile fume extraction systems and fully centralised extraction and filtra- tion solutions, alongwith on-torch fume extractors that can be supplied with a dedicated torch or as a retrofit that can be fitted to any torch. Nederman produces the full range of hi-vac and low vac systems coupled with a number of dust filtration and collection systems,” he says. Centralised high-vac systems, ac- cording to Herteberger, are typically mounted onto the welding torch and

in fume as particle in the 0.01-0.1 µ m size range. This means they are easily inhaled deep into the lungs and can penetrate facemasks. Chromium-6 is a known carcinogen and investigations have proved that exposure has a very dangerous effect on a person’s health,” Hoon warns. Back in 2006, theOccupational Safe- ty and Health Administration (OSHA) in the USA significantly lowered the permissible exposure limit (PEL) of chrome-6 from 50 to 5.0 µ g/m 3 as an eight-hour time-weighted average (TWA). Fume from manual metal arc (MMA) welding and flux-cored arc weld- ing (FCAW) contain a high proportion of components coming from the electrode coating or the flux-core, while little comes from the filler metal. Fume from metal inert gas (MIG) and metal active gas (MAG) processes, on the other hand, while theymay look less ‘smoky’, contain high concentrations of themetals being deposited, which can make these pro- cesses even more dangerous. “Any particle size less than 0.5 µ m in welding fume can reach the lungs, causing health risk including: cancers; asthma; nasal and skin ulcers (chrome holes); allergic and irritant contact der- matitis; lung disease (siderosis); fertility complications; and infarctions (tissue death). Company’s can also reduce the number of sick-days taken by welders, simply by removing their exposure to fume,” Hoon suggests. “Andwhile respi- rators are also an option, welders don’t like towork an eighth-hour shift breath- ing through a mask,” he adds. Collected dust, continues Herte- berger, can also pose a fire or explosion risk: “We supply FX-rated (explosion proof) hoods and air filtration systems for applications such as aluminium grinding, because aluminiumdust poses an explosion risk if ignited. Any dust can, in fact, be dangerous, so it needs to be properly handled and disposed of in a

involve suction pressures of -20 kPa at high airflow speeds and relatively low volumetric flow. “High-vac would typically be used with 38 mm pipe on the extraction arms,” he explains, add- ing that these systems extract less of the surrounding air but they need to be very close to the source, “typically 50 mm away”, hence their suitability for on-torch use. “These solutions are quite universal and canevenbe attached togrinders, for example,” adds Hoon. “On-torch extrac- tion is an excellent at-source solution that has been proven to have no effect on gas shielding, but people remain sceptical,” he reveals. “Low-vac systems, on the other hand, are designed for higher volume flows at lower suction pressures, in the order of 1.5 kPa.” Welding fume is particularly harm- ful because of the metal vapour and particles in the fume. “Stainless weld- ing, for example, produces chromium-6 or hexavalent chromium, which exists

Nederman’s Filterbox can be used with more that one extraction arm. These systems have a self- cleaning filter that operates via reverse pulse compressed air, along with a scraper.

32

June 2015

AFRICAN FUSION