Summary
Welding is a basic process widely used in various industrial manufacturing fields. However, it generates harmful byproducts such as arc light, electromagnetic radiation, toxic gases, and smoke particles. These byproducts not only pollute the environment, but also pose a major health risk to employees.
Among these hazards, welding fumes are the most complex and challenging to control in welding production. Therefore, conducting research on welding fume control is essential to improving the welding production environment and protecting employee health.
This article provides a summary of the formation mechanism, hazards and treatment measures of welding fumes. It also analyzes the challenges encountered in treating welding fumes in engineering applications and identifies the development direction of welding fume treatment.
Related Reading: The Ultimate Guide to Welding
Preface
As a fundamental process of modern manufacturing, welding technology has evolved from traditional single-connection methods to a multidisciplinary hot forming technology that integrates electricity, machines, materials and computers. It plays an irreplaceable role in various fields such as engineering machinery, water conservation and hydropower, shipbuilding, transportation, military equipment and others.
However, the welding process emits arc radiation, high temperature, noise, welding fumes and toxic gases that not only pollute the environment but also put the health of employees at risk.
Although masks and hearing protectors offer good protection against arc light, high temperature and noise, they are not as effective against welding fumes, which are the main carcinogens.
Welding fumes mainly contain toxic gases and soot particles. Soot particles can cause asthma, bronchitis, pneumonia, pulmonary edema, acute poisoning, diseases of the nervous system and even pneumoconiosis, heat from metal vapors, changes in respiratory function, cancer and other diseases.
Toxic gases such as CO asphyxiation gas, irritating gases such as ozone, fluoride, chloride, sulfur dioxide, and nerve-toxic gases such as nitrogen oxide and phosgene can cause headaches, dizziness, coughing, sputum, chest pain, tinnitus, tension and anxiety among employees.
The poor quality of the welding environment due to welding smoke and other associated hazards has resulted in a decline in the number of people willing to carry out welding work year after year. This has become one of the prominent problems restricting the healthy development of the welding industry.
In recent years, with the substantial increase in welding fabrication workload and the popularity of efficient welding methods such as flux-cored wire and other high dust-producing processes and materials, occupational problems caused by welding fumes have become increasingly common. become increasingly prominent.
At first, the allowable concentration of smoke and dust in the air of workshops in China was 6 mg/m 3 .
Currently, the China Welding Association has lowered the allowable concentration of smoke and dust to 4 mg/m3 and set clear requirements for the amount of dust generated by welding materials. In light of the risks associated with welding fumes, the American Welding Society has also developed a ventilation manual to reduce the concentration of welding fumes in workshops.
At the turn of the century, Japan established relevant standards to restrict the concentration of smoke and dust in welding workshops and actively promoted the research and development of new welding materials.
However, in actual production, particularly in areas with high welding intensity and relatively enclosed spaces such as shipyard workshops, soot concentrations can reach 9-18 mg/m3 and up to 38-312 mg/m3 in sectional confined spaces. cabin, which is far above the minimum soot concentration required by standards and is extremely harmful to human health.
It is clear that reducing hazardous substances in smoke and dust and improving the working environment for welding professionals has become an urgent issue that needs to be resolved in the welding industry.
Currently, welding fume treatment at home and abroad is mainly carried out in the following three directions:
(1) Strengthen Personal Protection; (2) Optimize Welding Processes and Materials; (3) Ensure adequate ventilation and smoke exhaustion.
This article analyzes the mechanism of welding fume generation and compares the advantages and disadvantages of current conventional fume control measures. It proposes a new concept of welding fume control through intelligent manufacturing, which provides a useful reference for improving welding fume control.
Due to the physical and chemical hazards of welding fumes to employees, it is crucial to protect their health and maintain air quality in the welding operating environment. This can be achieved by understanding the generation mechanism and factors that influence welding fumes, exploring the process of generation, growth and polymerization of welding fumes, and controlling and protecting the fumes at the source.
Furthermore, this approach establishes a theoretical basis for industry admission standards for welding fumes.
Welding fume formation mechanism
Early research suggested that the mechanism for generating welding fumes was a process involving superheating, evaporation, oxidation and condensation, as illustrated in Figure 1.
In the welding process, the temperature at the center of the arc is high, causing the evaporation of both liquid metal and non-metallic substances, which in turn generates high-temperature steam and maintains a certain concentration of particles.
As the high-temperature vapor reaches the low-temperature area at the edge of the arc, it rapidly oxidizes and condenses, resulting in the formation of “primary particles”.
These primary particles are generally spherical and have a diameter of 0.01-0.4 μm, with the majority being 0.1 μm.
Due to the static electricity and magnetism of the primary particles themselves, they will polymerize and form “secondary particles” as the temperature decreases, which will then diffuse in a specific way.
Shi Yuxiang from Wuhan Jiaotong University of Science and Technology conducted an in-depth study on the formation mechanism of welding fumes. He proposed an aerosol mechanism for welding fumes, which aimed to explain the process of steam and smoke transformation.
He suggested that the nucleation mechanism of welding aerosol particles near the arc is divided into homogeneous nucleation and heterogeneous nucleation.
The spectral distribution, morphology, composition and structural characteristics of the primary particles were systematically investigated both experimentally and theoretically through direct sampling electron microscopy and DMPS.
It was found that Fe3O4 crystals were mainly composed of 0.01 μm scale particles originating from welding aerosols, while 0.1 μm scale smoke particles had two types of crystal structures, spinel-type and fluoride, which were formed by the heterogeneous transition condensation mechanism of vapor particles.
Soot particles above 1 μm in scale were mainly formed by the bubble particle transition mechanism. Additionally, a welding arc particle nucleation zone model is proposed, which is of great importance in analyzing the formation process of welding aerosol particles.
Soot particles generated during welding undergo growth in the diffusion process through aggregation and fusion.
During the fusion process, several primary particles fuse into a single large particle, where the total surface area of the latter is less than the sum of the surface areas of the primary particles, and there is no boundary between them.
In contrast, the aggregation process is composed of dozens, or even hundreds, of primary particles that adhere to the surface, exhibiting distinct boundaries between particles.
Regardless of whether particle aggregation or fusion occurs, the size, shape and concentration of particles in welding fumes will change.
Dangers of welding fumes
The welding process can produce large amounts of smoke and toxic gases that are harmful to human health.
A significant proportion of welding smoke consists of suspended particles that diffuse into the air, while another portion is dispersed as toxic gas.
Soot particles produced during welding exist mainly as metal oxides, which are complex in composition, highly viscous and have high temperatures, with non-uniform particle sizes.
Typically, welders have a breathing capacity of around 20 L/min in production welding environments. Therefore, its respiratory capacity during one year is approximately 2,300m3.
In poor welding production environments, a worker can inhale 100g of particles per day and 2.5kg of harmful substances over 25 years of work.
Table 1 shows common metal oxide particles produced during welding and their associated hazards.
Table 1 Particulate Hazards in Welded Fumes
| Material | Source | Danger |
| ferric oxide | Of filler material and base metal | Iron pneumoconiosis or iron deposition disease caused by prolonged inhalation |
| aluminum oxide | Welding process of aluminum-based materials | Dust deposition in the lung causes pneumoconiosis |
| manganese oxide | Welding process from welding materials containing manganese | Irritant to the respiratory tract, causing pneumonia. Long-term exposure will damage the nervous system |
| Oxide | Basic electrode or coated wire | Irritant to gastric mucosa, causing bone damage |
| Barium compound | Barium containing welding filler | Toxicity, causing potassium deficiency in human tissues |
| Nickel Oxide | Pure nickel or nickel-based alloy welding materials | Damage to the nasal mucosa and lung cancer, Class I carcinogen |
Depending on the size of the particles, welding fumes can cause varying degrees of damage to the human body.
The team led by Yang Lijun from Tianjin University conducted research on the particle size distribution of MIG welding fumes, analyzed the impact of welding parameters and droplet transfer on the particle size of fumes. The results showed that soot particles exhibited nearly quantized distribution characteristics, with particle sizes mainly falling in the range of 0.1 to 1 μm, accounting for more than 85%, and particle sizes less than 0.1 μm representing about 10%. Furthermore, welding processes, droplet transfer shapes, and welding parameters had certain effects on the size of soot particles. Specifically, decreasing welding voltage led to a reduction in soot particle size.
Gomes JF et al. calculated that the particle size of welding fumes generated during the welding process was approximately 0.5 μm.
Research has shown that smoke particles with a diameter of more than 10 μm in the air are deposited in the nasopharynx, while those with a diameter of less than 10 μm can be inhaled by the human body. Smoke particles with diameters of 2 to 10 μm can be released, but those with diameters less than 0.5 μm will be deposited in the lungs and are difficult to remove.
Table 2 shows the residual amount of TiO2 with different particle sizes in rat lung tissue over several days (unit: μg). The smaller the particle size, the more penetrable it is and the more difficult it is to eliminate from the body. Furthermore, smoke particles will disperse into smaller primary particles in human alveoli, exacerbating their harmful effects on the body.
Table 2 Content of different sizes of TiO 2 in rat lung tissue （μg）
| Time/day | TiO 2 -D(0.03μm) | TiO 2 -F(0.25μm) |
| 1 | 347.7±13.1 | 324.3±6.1 |
| 29 | 202.8±23.0 | 172.8±12.1 |
| 59 | 140.9±22.6 | 128.5±16.6 |
LaurynMF et al. found that Fe2O3 is the only metal oxide that promotes lung cancer, and the tendency of metal oxides to cause lung inflammation is Fe2O3 > Cr2O3+CaCrO4 > NiO. Among them, the toxic effect of Fe2O3 on the lung is continuous, while the toxic effect of Cr2O3+CaCrO4 on the lung is acute.
Roth JA et al. found that prolonged exposure to welding fumes and excessive manganese inhalation can have adverse effects on human health, including damage to the lungs, liver, kidneys and central nervous system. Male workers are at greater risk of infertility.
Prolonged exposure to environments with manganese concentrations greater than 1 mg/m3 may increase the risk of manganese poisoning, similar to Parkinson's disease.
In addition to the many harmful smoke particles produced by welding, it also emits many harmful gases, including carbon monoxide, nitrogen oxides, ozone, phosgene, hydrogen fluoride and other harmful components.
Table 3 lists the dangers of harmful gases present in some welding fumes to the human body.
Table 3 Harmful gases and hazards in welding fumes
| Harmful gas | To produce | Danger |
| Carbon monoxide | Welding flux or shielding gas is produced by the combustion and decomposition of carbon dioxide. | Headache, dizziness, confusion, choking |
| Nitric oxide | It is produced by the action of ultraviolet rays generated by the electric arc on nitrogen in the air | Irritation of the eyes and respiratory tract, leading to lung congestion |
| Ozone | It is produced by the interaction of ultraviolet rays generated by the arc and nitrogen in the air | The respiratory tract becomes dry, causing headache, fatigue, lung congestion and lung disease |
| Phosgene | It is produced by the decomposition of fluorine-containing solvent, polytetrafluoroethylene, surface coating, etc. | Irritant to the respiratory tract, nose and eyes, toxic, causing pulmonary edema. |
| hydrogen fluoride | Electrode coating and flow | Irritation in the eyes, nose, throat, lung congestion, bone changes |
Welding fume protection
Comprehensive measures should be taken to purify the welding working environment and protect the health of employees by reducing source emissions, strengthening protection and promoting technological innovation. This will help ensure that the concentration of harmful substances generated by welding remains within the permitted range.
Currently, there are several common treatment measures available, such as personal protection, optimization of the welding process and materials, and implementation of ventilation and smoke exhaust systems.
1. Personal protection
Personal protective measures for welding fumes mainly involve the use of ventilation and dust removal masks, as well as other respiratory protective equipment, to reduce the harm caused by welding fumes to workers.
Figure 2 illustrates four respirator filtration mechanisms for smoke and dust particles of various sizes.
(1) Effect of gravity:
As air containing dust particles passes through the fiber layer of the filter material, the particles are displaced from the direction of airflow by their own gravity and are deposited on the filter material.
Typically, dust particles larger than 1 μm are filtered effectively, while smaller particles can be ignored due to their minimal effect on gravity compared to gas flow rate and other factors.
(2) Interception effect:
The fibers within the filter material are irregularly stacked and intertwined with each other.
As the high-velocity smoke particles in the air come into contact with the fiber material, they attach to the surface of the fibers, resulting in effective particle interception.
(3) Inertia effect:
Smoke particles are deposited on the fiber surface due to the effect of inertial force as the airflow changes direction frequently as it passes through the filter material, causing them to separate from the streamline. This phenomenon is particularly true for smoke particles with a particle size of 0.5 ~ 1.0 μm, which are mainly intercepted by the inertial effect.
(4) Diffusion effect:
Particles with a diameter of less than 0.1 μm at room temperature move mainly through Brownian motion. The smaller the particles, the easier they will be removed.
Particles larger than 0.5 μm are mainly in inertial motion. The larger the particles, the easier they will be removed.
Particles between 0.1 μm and 0.5 μm have no obvious diffusion and inertia effects and are difficult to remove.
During welding, the size of smoke particles varies from 10-3 to 102 μm over five orders of magnitude, with 0.1-0.5 μm particles being the most penetrating.
Currently, no respirator can achieve an ideal filtering effect on all smoke particles.
At present, personal protective equipment has a weak protective effect on toxic gases, and the prevention of toxic gases cannot be achieved through personal protection alone.
2. Optimization of welding process and welding materials
Optimizing welding processes and materials mainly involves controlling welding fumes, reducing the rate of fume generation and the content of toxic substances within them.
There are several factors that affect the amount of welding dust produced.
Currently, research on welding dust in national and international environments mainly focuses on two aspects:
The first studies the influence of various welding methods and process parameters on the amount of dust generated, and the second studies the impact of the composition of the welding wire, coating and shielding gas on the amount of dust produced.
2.1 Impact of the welding process on dust emission
The amount of dust generated varies depending on the welding method used.
When the same process parameters are used, MIG welding produces a much higher dust generation rate than non-MIG welding. On the other hand, the smoke generated by submerged arc welding is minimal.
Related Reading: MIG vs TIG Welding
Table 4 shows the amount of dust generated by various welding methods under identical specifications.
In general, when using the same welding method, the amount of dust produced increases as the welding current and voltage increase.
Compared to DC welding, AC welding generates a greater amount of dust, but the amount of dust decreases as the welding speed increases.
Table 4 Dust generation rate of different welding methods
| Welding process | Generation rate/(mg·min -1 ) |
| FCAW | 900~1300 |
| SMAW | 300~800 |
| MIG/MAG | 200~700 |
| GTAW | 3~7 |
| MOUNTAIN RANGE | 3~6 |
The generation of large amounts of dust from flux-cored wire welding, shielded metal arc welding and MIG welding has a serious impact on both welders and the environment, making it an important focus of research both nationally and internationally.
Shi Qian and colleagues from Lanzhou University of Science and Technology conducted research on the amount of dust generated by self-shielded flux-cored wire welding under different process parameters.
Their findings indicate that in small specification welding, the amount of dust generated increased significantly due to increased spatter during the short circuit transition and slag column transition. In large specification welding, the evaporation rate of the droplet and heated base metal is accelerated due to the increase in heat input, resulting in an increase in the amount of dust generated. The droplet transfer mode had little effect on the amount of dust generated.
These results were also confirmed in Zhang Junqiang's research on the smoke and dust generation mechanism in self-shielded flux-cored wire welding. The study found that the aggregated smoke and dust generated in the smoke and dust splash area and the smoke and dust droplet area greatly increased the total amount of smoke and dust.
Yamamoto et al. used CO2 as shielding gas when welding with 26% flux cored wire.
As the welding current increases, the amount of welding dust gradually decreases.
The author also developed an advanced arc welding process protected by pure carbon dioxide gas using the pulse current method to control the droplet.
This method uses high current to melt the welding wire and then reduces the current during droplet transfer. This ensures that the droplet can be smoothly transferred to the molten pool with constant length, resulting in the regular formation and separation of metal droplets and reducing the amount of dust generated by 50%.
Scotti studied the influence of arc length, droplet diameter, and short-circuit current on the amount of dust generated by GMAW using a variable control method.
The results show that during the short-circuit transition, an increase in droplet diameter, short-circuit current and arc length leads to an increase in the amount of dust generated. Higher short-circuit current makes the evaporation of metal on the surface of the liquid bridge more intense when the droplet enters the weld pool, increasing the amount of dust generated. When these factors work together, the increase in dust emission is more noticeable.
Bu Zhixiang of Hubei University of Technology and others conducted an orthogonal experiment with solid welding wire welding with CO2 gas shielding as the research object, and used welding current, welding voltage and welding speed as the three experimental factors. They considered the rate and amount of welding dust as experimental indicators.
Through analysis of variance and range analysis of orthogonal test data, the results show that the main factors affecting the formation rate of welding fumes are welding current and voltage, and welding speed has no significant effect on the rate of formation of welding fumes. When the welding voltage is 22-24 V, the welding current is 290-320 A, and the welding speed is 26 cm/min, the amount of welding dust is the lowest.
The amount of welding smoke is not only related to the filler material, but also closely related to the composition of the shielding gas.
KR Carpenter et al. added O2 and CO2 to the GMAW shielding gas and found that adding 2% O2 to the Ar-CO2 binary mixture had no effect on the dust generation rate.
When the O2 in the ternary mixture increases, the dust generation rate increases at the 5% CO2 level, but does not increase significantly at the 12% CO2 level.
The amount of dust generated can be controlled by adjusting the amount of CO2 added to the mixed gas, according to a study by Li Zhuoxin's team at Beijing University of Technology on the Cr (Ⅵ) content in stainless steel welding fumes.
Their results indicated that the mass fraction of Cr (Ⅵ) in smoke increased with stronger oxidation of shielding gas during shielding gas welding. Furthermore, Cr (Ⅵ) increased with higher electrical currents (150 ~ 250 A) during MAG welding, and the mass ratio of Cr (Ⅵ) in the short-circuit transfer fumes to total Cr was higher than than that of jet transfer fumes during GMAW.
A report presented by Vishal Vats at the interim meeting of the Eighth Committee of IIW 2022 pointed out that the addition of oxygen to the GMAW shielding gas would promote the formation of Cr3+ and Cr6+ as well as increase harmful elements such as Mn, Fe and Ni in the smoke.
These findings suggest that the amount of welding dust is influenced by welding process parameters, and selection of appropriate parameters can reduce dust emissions and promote a healthier environment. However, there is a coupling effect between the welding process and welding quality that may require sacrificing quality and efficiency to reduce smoke emissions, which presents limitations in practical applications.
The increasing use of efficient welding methods (double-wire/multi-wire welding, hybrid laser arc welding) in engineering further increases welding specification requirements and makes welding fume treatment more challenging.
2.2 Effect of welding materials on dust emission
During the welding process, metal oxides produced by welding materials at high temperatures mix with various carcinogens. If operators inhale these particles excessively, it can cause a range of illnesses.
To mitigate these risks, the development of green welding materials can effectively control harmful smoke and dust components at the source.
Research on green welding materials at home and abroad mainly focuses on three aspects:
(1) By modifying the composition of the medicine film, it is possible to reduce the amount of dust generated by the material.
(2) To reduce the content of heavy metal elements in welding smoke and dust.
(3) Welding fumes must be treated with deactivating welding materials.
The amount of dust generated during welding is influenced by the composition of the electrode coating, the chemical composition of the powder and the steel strip of the welding wire. The influencing factors are complex.
Fluorite and sodium silicate are the main contributors to the generation of dust on the electrode coating, and their reaction products account for more than 50% of the total amount of smoke and dust.
Materials containing K and Na increase the amount of dust generated, while silicon-calcium alloy and magnesium powder can inhibit it.
Research by Jiang Jianmin and others at Beijing University of Technology found that reducing the iron powder content in the wire flux core can decrease the amount of dust generated during welding by 33% to 47%.
According to a report by Mruczek MF, a foreign welding material manufacturer has developed a low-manganese flux-cored wire that can effectively reduce the Mn content in welding fumes. However, this can lead to poor mechanical properties of the weld.
North TH found that adding Mn-containing composite particles to the core can significantly reduce the Mn content in welding fumes, preventing Mn oxidation and leaving more Mn in the weld.
Dennis JH et al. added active elements (Zn, Al, Mg) to the flux-cored wire, which can significantly reduce the Cr6+ content in welding fumes, allowing the active elements to oxidize preferentially. However, adding Zn to stainless steel welding wire can reduce the Cr content in welding fumes but accelerate the smoke formation rate.
Mortazavi SB et al. found that reducing the K content in welding materials and increasing the Li content can reduce the K2CrO4 content and subsequently reduce the Cr6+ content in welding fumes through Li.
Furthermore, Topham N et al. demonstrated that reducing the Na and K content in austenitic stainless steel welding materials and adding 30% tetraethyl silane (TEOS) in the shielding gas can reduce the Cr(VI) content in stainless steel welding fumes .
However, the welding materials shutdown method used to reduce harmful components in welding fumes may not meet the requirements for mechanical properties, corrosion resistance and wear resistance needed for welding structures.
Currently, the degree of alloying in the base metal used is very high. From low carbon steel to low alloy steel and then to high entropy alloy, the alloy level is increasing.
Simultaneously, adding alloy elements such as Mn, Cr, Ni, Mo, Co and others to welding materials (base material+welding wire) can significantly improve the mechanical properties and corrosion resistance of welding components, increase their service life and expand the range of applications of metal materials.
As a result, it is often impractical to treat smoke and dust by shutting down welding materials in actual production.
3. Ventilation and smoke exhaust
Ventilation and smoke exhaustion are currently the most effective treatment methods in production, which mainly include two types of methods:
The first method involves installing local smoke extraction devices or using smoking welding guns at the welding station to control the further diffusion of welding smoke and noxious gases, and to control them from the source.
The second method involves improving the welding shop working environment through comprehensive ventilation and plant displacement ventilation.
3.1 Local smoke extraction
Currently, the main methods for local smoke extraction mainly include smoking welding guns and local ventilation and dust removal.
The principle of the smoking welding gun is illustrated in Figure 3. The smoking mouth generates suction to capture smoke and dust, preventing their diffusion and environmental pollution.
Compared to other site processing equipment, hot welding guns offer greater flexibility in terms of positioning and angle adjustment, allowing welders to operate with fewer restrictions.
Local ventilation involves the use of specialized hoods to directly extract welding fumes from the welding area and subsequently releasing the collected fumes outside after undergoing dust reduction treatment. The principle of local ventilation is represented in Figure 4.
Research indicates that local ventilation is more efficient than general ventilation.
Flynn MR conducted a study comparing the dust removal effectiveness of a local ventilation system under three conditions: no indoor ventilation, natural wind and mechanical ventilation. The results revealed that the fan combined with the local ventilation system had the highest dust removal efficiency.
In another experiment, Meeker JD evaluated commercial local ventilation and dust removal equipment. The study found that the concentration of Mn in air smoke decreased by 25%, particulate matter decreased by 40% and Cr6+ decreased by 68% after using the equipment. Therefore, local ventilation and dust removal is an effective ventilation method.
However, it should be noted that local fume extraction equipment is only suitable for welding small-sized parts and has limited application in heavy structure welding workshops. This is due to the fact that the welding station for heavy structures is mobile and the smoke and dust points are constantly changing, making it difficult to consider the total space using local dedusting.
3.2 General ventilation and displacement ventilation
General ventilation, also known as dilution ventilation, refers to the process of diluting indoor polluted air with clean air through the use of doors, windows and roofs. This is done to reduce the concentration of harmful substances in indoor air and ensure that the indoor environment meets air quality standards.
Its principle is shown in Fig.
General ventilation is suitable for environments with low concentrations of harmful substances and is commonly used as an auxiliary mode for local ventilation and dust removal.
CE Feigley et al. studied and discussed the safety factor K in the air volume calculation formula for dilution ventilation and proposed a more objective mixing factor Km based on experimental measurements.
Liu Siyan et al. carried out tests to evaluate the concentration of chemical hazards in a welding shop before and after implementing mechanical ventilation treatment. After ventilation treatment, the content of manganese and its compounds in the air, welding fumes, ozone, carbon monoxide and nitrogen oxides in the workshop decreased, with the most significant reduction found for manganese and its compounds at a decreasing concentration of 82%.
Displacement ventilation is developed based on general ventilation and its principle is illustrated in Figure 6.
Due to the heat generated during the welding process, a stable temperature gradient is formed in the welding shop, which reduces the wind speed and causes a temperature difference (ΔT=2~4 ℃) between the fresh air directly supplied to the internal desktop.
As a result, colder air sinks first under the influence of gravity and gradually spreads across the ground, forming a layer of fresh air. As the temperature rises, this fresh air rises, continually removing polluted air.
Furthermore, fresh air is continuously supplied to the room through the air duct, while the air return opening above the workshop draws indoor air due to multiple factors.
The cool air above the ground in the work area rises slowly, forming a uniform upward airflow. This gradually replaces the polluted air in the workshop, purifying the air.
The displacement ventilation dedusting method not only saves energy consumption but also provides higher purification efficiency. R. Nienel et al. conducted a study on the displacement ventilation system of large welding plants.
By analyzing the spatial distribution of particles generated during the welding process, they found that the concentration of particles in the personnel activity area at the bottom of the plant was significantly lower than the concentration at the top of the plant, thus demonstrating the effectiveness of ventilation. displacement in the discharge of particles from the welding plant.
Currently, research on displacement ventilation mainly focuses on optimizing air distribution, air supply parameters and displacement ventilation outlet position using CFD numerical simulation. This research aims to improve ventilation efficiency and provide theoretical guidance to optimize displacement ventilation design.
Conclusion
(1) The generation and danger of welding fumes are determined by complex physical and chemical processes and comprehensive measures are required for their treatment.
(2) Complete control of welding fumes and other hazardous factors cannot be achieved through passive protection alone.
(3) The innovation of welding processes and intelligent and automatic welding systems has opened a new path to achieving green and efficient welding and clean production.
