Extraction of Welding Fumes and abrasive Dust with a central Dust Collector System - Cartridge Filter0 pages

Welding fumes are complex mixtures of
substances made of metal oxides, silicates
and fluorides, which occur during machining
procedures, such as welding, thermal cutting
and related processes such as soldering, thermal spraying and flame hardening. These fumes
arise if metallic materials are heated beyond
boiling point, changed into gases, which then
cool down in the air and condense into ultrafine particles. These particles, whose diameter
is almost exclusively less than 1 m (<0.001mm!),
should be categorised as very hazardous to health
because they can penetrate the pulmonary alveoli
when inhaling. In higher concentrations or with
frequent exposure, these harmful substances can
lead to immediate symptoms (vertigo, headaches, “metalworker’s fever”), chronic obstructive
respiratory diseases (chronic bronchitis, asthma,
lung cancer) and damage to the central nervous
system (Parkinson’s disease).
According to the ordinance of Hazardous Substances 98/24/EC, employees must be protected
from hazardous substances and welding fumes
are declared as such a substance. In Germany, the
general threshold for alveolar dust is 3mg/m³ (see
Technical Rules for Hazardous Substances TRGS
900). As a general rule, pollutant concentrations
can occur in the breathing zone of the welder,
which can exceed the guidelines many times over,
when not using any ventilation measures - such as
extraction systems.
For high-alloyed steels, which contain more than
5 percent by weight in total of alloying elements
such as chrome, nickel and manganese, even
lower thresholds are compulsory for the work
environment of the employee. In this case, recirculated air operation of the filtered air is strictly
not permitted. Notwithstanding this principle, the
air extracted in a working area may be returned
there if it is sufficiently cleaned of such substances
using official procedures or those recognised by
Employer‘s Liability Insurance Association (e.g.
safety filter H13 as an afterfilter or energy recovery using a heat exchanger) or equipment (e.g.
W3-certified equipment).
Information on the state of technology relating
to the subject of “welding fumes” can be found in
BGR 220 , TRGS 558 and TRGS 560.

SFC filter cartridges

Problem
Zambelli Technik is a metal-working SME in the
Czech Republic, which enjoys a good reputation
as a manufacturer of ovens and chimneys and
as a supplier of the automobile industry. The
export-focused company has grown strongly in
the last few years and has successively expanded
its production capacities as a result of this. During
production, both welding fumes and abrasive dust
arise as part of the procedures.
The harmful substances should be extracted via
a central filter system, which should preferably be installed outside the production hall. The
filtered air should be returned to the hall during
the heating period via a summer/winter set-up
in order to use fewer resources and save heating
costs.
In addition welding fumes are classified as combustible, because during metal processing, i.e. when
sanding, ignition sources cannot be excluded,
resulting in a piping and filter fire. Conventional deflector plates and diversion offer no definite protection here, meaning that fire protection
tasks must be taken into consideration during the
system planning.

Solution
As described in the info box, approx. 99% of
the particles of welding fumes are smaller than
1 m and put the highest demands on the filter
medium. On one side, the filtration of ultra-fine
harmful substances must be reliable in order
to guarantee that the workplace and clean air
concentrations are at least below the existing
thresholds. However, on the other hand, moderate pressure losses should exist during long
service life of the filter cartridges in order to facilitate low operating costs.

Client: Zambelli Technik, spol. s.r.o, www.zambelli.de

EX TR AC TION OF WELDING FUMES AND ABR ASIVE DUST
WITH A CENTR AL DUST COLLEC TOR SYSTEM - CARTRIDGE FILTER

Extraction of Welding Fumes and
abrasive Dust with a central
Dust Collector System - Cartridge Filter