HOW TO CHOOSE A WELDING FUME EXTRACTION SYSTEM?
- Erol Köksoy
- Aug 5
- 12 min read
Updated: Sep 12
We have mentioned the damages of welding fumes in detail in our other blog posts.
For both human health and environmental cleanliness, safely filtering welding fumes should be the priority agenda of every company engaged in welded manufacturing.
Let's not forget that; similar things apply to gas, plasma and laser cutting fumes.
Absorption of welding fumes before they reach the breathing zones of people should be the primary goal.
Detailed evaluation should be made for the selection of products suitable for this target.
It is necessary to evaluate different options for this;
Mobile fume extraction units:
D300 Mobile welding fume extraction system These units are practical and safe products that can be easily moved around the workshop and have an acrobatic suction arm with a length of 2, 3 or 4 metres. The filtered air is given back to the working environment. The point to be considered here is to be careful when welding high alloy materials such as stainless steel. Such fumes classified as W3 must be filtered by specially manufactured units. Welding fume extraction systems manufactured in accordance with ISO 21904-4:2020 standard meet W3 requirements. Mobile systems are produced with different filtering technologies:
a. Units with mechanical (disposable) filters: In this type of units, there is a main filter that cannot be cleaned. Optionally, auxiliary filter equipment such as activated carbon filter, coarse filter, mesh filter can also be used. In this type of units, the sucked dirty air is directed directly to the filter.
While the cost of ownership is relatively low, the operating costs of these units can be high. The main filter element, which is generally disposable, has an average lifetime of 200 working hours. If we calculate over 5 hours of arc time per day, filter replacement may be required at the end of 40 working days.
b. Units with cartridge filter: This type of units have a cleanable cartridge filter. Optionally, auxiliary filter equipment such as activated carbon filter, coarse filter, mesh filter can also be used. The cartridge filter can usually be cleaned with a compressed air gun. Some manufacturers also offer cleaning systems with brushes, vibrators, etc. In manually cleanable units, it is useful to look for filter cleaning feature without disassembling the machine as much as possible.
Jet-Pulse filter cleaning Models with cartridge filters are also available with fully automatic cleaning. Such units automatically perform cleaning when the filter reaches a preset level of fullness. The most commonly used method is the jet-pulse system. These units, which contain a compressed air tank, must be continuously connected to a compressed air source.
Models with cartridge filters may have a slightly higher cost of ownership, but the operating costs are lower. This is because a cleanable cartridge filter can be used for several years, depending on usage, filter material and cleaning frequency.
c. Electrostatic filter units: These are systems that are mostly abandoned today. It keeps the particles in the smoke completely electrostatically on the plates. It does not require the use of a filter. However, the filtration rates of such filters may not be satisfactory. Such filters are mostly preferred for filtering coarse and sticky particles such as oil.
If a mobile unit is to be preferred, it is necessary to consider the following:
The welded parts must be small. Because a suction arm suctions from an average distance of 30-50 cm. If large parts are welded, mobile units should not be preferred as it will be difficult for the welder to move the arm continuously.
◦ If there are many welding stations but the area is not large enough, these units will cause overcrowding.
◦ If there are many welding stations, it is necessary to control the motor power of the mobile unit. For example, if 20 mobile units are to be purchased and one unit has a 1.1 kW motor, the total power will be 22 kW. If this power can be reduced to 10-15 kW with a centralised system, mobile units may not be preferred due to energy saving.
◦ If a unit with manual cleaning cartridge type filters is preferred, it should be ensured that the filters will be cleaned as often as necessary. Otherwise, the filters may clog very quickly and cause unnecessary costs.
Central extraction system with acrobat arms:
Central fume extraction system with acrobat extraction arms It is a highly preferred system. Several branches connected to a central fan provide smoke extraction through a pipeline. There are different alternatives in these systems:
a. Systems installed with fan only:
We do not recommend these systems. Because;
◦ Since there is no filter system before the fan, the fan will fail very quickly. Particles accumulate on the fan blades and the aerodynamic structure of these blades deteriorates. As a result, the desired air flow rate cannot be obtained after a while. In addition, the fan requires frequent balancing.
◦ Since there is no filter system, all harmful gases and particles in the smoke are thrown into the atmosphere. It is a very dangerous situation for the environment.
◦ Since the sucked air will be thrown out directly, it increases the heating costs in winter months. To give an example; When a system is installed with 15 suction arms (each arm absorbs an average of 1000 m³/hour of air), an average of 15.000 m³/hour of air will be absorbed. The heated 15.000 m³ air in the workplace will be discharged within one hour. In an 8-hour shift, this amount will be 120,000 m³. A production area with a total area of 2000 m² and a ceiling height of 10 metres has a total volume of 20,000 m³. Discharging almost all the air of such a working area in one hour will make it very costly to heat this workshop in winter.
◦ Using the same example, 15,000 m³/hour of outside air must also enter this work area. Otherwise, the negative pressure environment and insufficient air inside will make the employees very uncomfortable. In the past, we have also witnessed that the entrance doors are very difficult to open due to this negative pressure in some enterprises that make similar applications. Therefore, openings that allow sufficient air to enter easily from outside must be provided in appropriate areas of this work area.
b. Centralised systems with filters: Systems that filter the absorbed fume and then return it to the working environment will prevent the above-mentioned negativities.
If a central extraction system with acrobat arms is to be preferred, the following should be taken into consideration:
◦ The welded parts must be small. This is because a suction arm can suction from an average distance of 3050 cm. If large parts are welded, it should not be preferred because it will be difficult for the welder to move the arm continuously.
◦ The system must be designed by a professional company. Factors such as pipe diameter calculation, fan selection, filter selection are necessary for proper operation of the system.
High efficiency fan/motor should be selected as much as possible. It is possible to do the same work with lower energy consumption. The investment cost may be higher at first, but this difference will be recovered in a very short time.
◦ A flap system should be foreseen for each arm. When the welder, who is not working at that moment, keeps the flap of the suction arm closed, systems that can reduce the motor rotation speed according to the number of open arms should be used. There are also systems with flaps that close automatically when there is no more welding process. These systems are equipped with special particle sensors.
c. Downdraft extraction tables:
KT20 Welding and grinding table with downdraft extraction Downdraft welding tables can be preferred with mobile or central connection. Downdraft tables can absorb welding fumes and grinding dust before they rise. They are ideal for operations where relatively small parts are welded.
But these tables also have disadvantages:
◦ In gas shielded (MIG, MAG, TIG etc.) welding methods, there is a risk of suction of the shielding gas.
◦ If a centralised system is installed and the sucked air is discharged directly, it increases the heating costs in winter months.
◦ In multi-table applications, when the extraction process is used with a central suction system, if all the air sucked from the tables is discharged outside the working area, a sufficient amount of fresh air must also enter the working area from outside. Otherwise, the negative pressure environment and insufficient air inside will disturb the workers. In the past, we observed that in some facilities with similar applications, opening the entrance doors was extremely difficult due to this negative pressure. Therefore, appropriate openings must be provided in suitable areas of this work area to allow sufficient air to easily enter the work area.
◦ Mobile tables must have a fire prevention system. Sparks arising during the welding process must be damped before reaching the filter.
d. Fume extraction systems on torch:
In these systems, a special MIG or TIG torch is connected to a high vacuum unit to suck out the fumes before they spread. Some companies are also developing suction equipment that can be mounted on conventional torches. Torch mounted suction systems are not limited to manual welding torches. It can also be applied with automation torches and welding robot torches.
HiVent MH25 In fact, applications with automation and robot torches can be more efficient than manual torches.
The disadvantages of this system can be listed as follows:
◦ If the gas flow rate is high, the smoke is pushed away from the suction nozzle. In this case, the suction efficiency decreases.
◦ If there is too much spot welding, i.e. too frequent triggering, the fume extraction efficiency decreases because there will be a higher pressure gas outlet at the start of the arc. It is necessary to use special equipment to regulate this pressure change. Again, in applications such as spot welding, fume extraction may not be possible because the welder will move fast.
The angle between the welding pool and the torch is very important. If the torch is not held at a suitable angle, suction efficiency decreases.
◦ Welding position and method affect the efficiency. The most efficient area is fillet welding. It can also be said to be slightly efficient in the PA position. Suction efficiency can be very bad in PC, PD and PE positions.
Welding positions ◦ Anti-spark sprays and pastes affect suction efficiency.
◦ Each torch manufacturer may recommend different air flow rates for their products. For this reason, suction units with adjustable air flow rate should be preferred as much as possible. It is useful to check the air flow rate frequently with the air flow measurement apparatus supplied with the torches.
◦ Since the suction units used for this system are designed in a small size, the filter surface may be small. In this case, there is a risk of frequent filter replacement. For professional use, we recommend systems with automatically cleanable cartridge filters.
◦ Smoke suction torches are slightly heavier than conventional torches. They can be a problem for welders during long shifts. In addition, since the consumables of these torches are different, their costs can be high.
Rules for fume extraction torches
e. Hall ventilation systems:
They are efficient systems. It should be preferred for all production areas where local suction cannot be done. It is preferred for filtering all volatile particles in the working environment.
If we examine the welding fume in particular; When the welding fume particles, which rise very rapidly due to the thermal effect, reach a certain height, they are suspended first. Depending on many different factors such as season, ambient air currents, this height will form a cloud-like cloud in the range of 2.5-5 metres on average. Most of these particles, which cool down thoroughly, are directed downwards by the effect of gravity. But since these particles are quite light, they can move up to 40 metres. In other words, they are scattered all over the production area and even inside the office.
HiVent HiS The priority of ambient ventilation systems is to absorb and filter these volatile particles without allowing them to spread and to provide filtered air to the environment again. These systems provide savings of up to 70% in heating costs in winter months since they do not take in air from outside and do not give air to the outside. Some manufacturers add cooling and heating features to these systems.
The ACH (air changes per hour) required for the ambient air to reach a particulate exposure in accordance with the legal limits must be calculated correctly. The exposure rate is applied differently in each country. Germany reduced the exposure rate from 3 mg/m³ to 1.25 mg/m³ in 2012. In order to calculate the number of towers, a lot of information is needed such as the amount of welding machines in the working area and the projected future numbers, the operating amperes of the machines, arc times, shift numbers, other pollutants in the environment. The expert team that will design the system should take this information and calculate the total amount of pollutants generated in this environment and make the necessary design calculations to reduce the target exposure rate.
It should not be forgotten that; trying to remove such volatile particles from the environment with ceiling type fans is not an efficient solution. There are of course areas where it can be applied, for which a specialised team should be asked for help.
Important note: Ambient ventilation systems are not used alone. Employees must use appropriate PPE (e.g. PAPR system).
There are different types of ambient ventilation systems.
a. Push-pull systems:
Push-Pull hall ventilation system One of the two pipelines placed opposite each other pushes the polluted air, while the other absorbs this air and transmits it to the filter system. The filtered air is sent back to the blowing line. Our recommendations for these systems are that the ceiling height should be lower than 7-8 metres and the thermal load should not be high, i.e. the annual consumption of welding wire/electrode should be less than 10 tonnes/year.
The design of these systems must be carried out by specialised teams. Often due to incorrect calculations, the particles above are pushed downwards in the areas where these systems are installed and cause harm instead of benefit.
These systems are designed and installed for a specific area. Moving it to an area with other dimensions will cause negative effects. When there is an excessive increase in the number of welding machines during the installation period, the system will again become inoperable. For this reason, the increase in the number of sliding machines that may occur in the following years should also be foreseen at the order stage.
b. Layered systems:
Layered hall ventilation system These systems are much more efficient. Pipelines placed upwards suck the polluted air and send it to the filter system. The filtered air is transported by pipelines and reintroduced to the environment at low speed through diffusers placed at ground level. In some applications, this fresh air is cooled a little more and its effect is increased. These systems, which are installed with the principle of displacement ventilation, always keep the polluted air above the breathing zone. Ideal for halls with high ceilings and high thermal loads. The biggest disadvantage is the cost of ownership. These systems are designed and installed for a specific area. Moving it to an area with other dimensions will cause negative effects. If there is an excessive increase in the number of welding machines during the installation period, the system will again become inoperable. For this reason, the increase in the number of welding machines that may occur in the following years should also be foreseen during the ordering phase.
c. Tower systems:
OHK15 filter tower These systems are completely pipe-free. They work with the logic of the air purifiers we use in our homes. Two systems are generally used.
c.1. Top blown towers: These towers suck the polluted air from below and the filtered air is blown back into the environment by jet nozzles at the top. They are usually designed to be more than 5 metres high. Thus, they quickly disperse the particle cloud formed over the production area.
Disadvantages of this system:
Depending on the manufacturer, there must be an obstacle 20-30 metres away from the tower. For this reason, installation problems occur in wide halls with open spaces.
As they absorb polluted air from below, mixed air constantly passes through the breathing zone. In other words, it is difficult to talk about completely clean air in the breathing zone.
As they are quite large systems, transport and installation processes are costly and long.
They always provide clean air in the breathing zone. The clean air blown from the bottom side spreads to quite far areas and prevents harmful particles from coming down as it heats up and goes up.
The disadvantage of this system is;
The cloud of particles accumulated above dissipates more slowly or sometimes not at all. This creates a psychological belief that the tower is useless. Because these towers move the particles above at a much slower speed. c.3. Double-sided blowing towers: This tower system was first developed and patented in Turkey. It has the same features as the bottom blowing towers. In addition, thanks to the jet nozzles placed on the upper side, the user can disperse the particle cloud at any time. These towers have 5 different fresh air blowing modes.
◦ Completely bottom blowing
◦ Completely top blowing
◦ 30% bottom and 70% top blowing
◦ 50% bottom and 50% top blowing
◦ 70% bottom and 30% top blowing
Thanks to these mode selections, many different installations can be realised. d. Swarm type systems: These systems are also developed in Turkey. They offer the advantages of much less energy consumption, much less space occupation, much easier installation and maintenance. A swarm member suspended about 4-5 metres above the ground absorbs and filters the polluted air and releases a large proportion of the filtered air to the environment at low speed with the diffuser on the ground, while a part of the air is blown horizontally with a jet nozzle and pushes the polluted air towards the other swarm member. These air ratios can be adjusted.
Swarm type ambient ventilation d. Fume extraction with extractor hood:
If suction hoods are to be used for manual welding operations, appropriate PPE is required. Hoods are mostly preferred in robotic welding systems. The size and height of the hood should be calculated very well.
Effects of the hood distance You can consult our expert team to determine the most suitable system for your needs.
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