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AFRICAN FUSION
June 2015
Envirox: Fume extraction systems
“
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
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
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.
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.
Fume extraction:
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