When a machine becomes so powerful that it can cut through thick metals like a hot knife through butter, it is bound to become a common staple in workshops everywhere. Plasma cutting has grown to become one of the most widely-used cutting solutions, with everyone from metal fabricators, to sign makers, to do-it-yourselfers using this technology. While there is a lot to be said about plasma cutting technology, from its high-temperature performance to its high-quality precision, some shops have swept its greatest hazard under the rug. When left uncontrolled, dust and fumes produced during plasma cutting can have a severe impact on your workers, your work environment, and the external environment as a whole. We created this guide to help you recognize the potential health hazards in your workshop and implement the necessary dust and fume extraction systems. We hope that with the help of our guide, your shop will be on its way to having a healthy, sustainable, and eco-friendly work environment for all to enjoy!
Dust and Fumes
Fume produced during welding is comprised of solid particles, usually less than 1.0 µm in size, formed by condensation and oxidation of the vaporized metal. These particles are capable of being deposited in the gas-exchange region of the lungs. The chemical composition of the welding fumes and gases depends on the welded material, the process, and the electrodes used. However, the potential health hazards from exposure to welding fumes are also dependent on the work environment, the type and quality of exhaust ventilation, degree of enclosure of the work station, length of exposure, and personal protection equipment.
Prolonged exposure to welding fumes and gases at high concentrations may cause the following:
- Metal Fume Fever
- Nervous System Disorders
- Irritation of Respiratory System
- Eye, Nose and Throat Irritation
- Chest Pain
- Kidney Damage
- Fluid in the Lungs
- Bone and Joint Problems
- Headaches and Dizziness
Section 19.5 of Part XIX of the COHSR states that employers shall take preventive measures that consist first of the elimination of hazards, then the reduction of hazards and finally, the provision of personal protective equipment. As part of the preventive measures, adequate ventilation must be provided for all welding and allied processes. The combination of dilution ventilation and local exhaust is the most successful method in controlling welding fumes and gases.
Types of Ventilation
1. Dilution Ventilation
Dilution ventilation is an engineering control that uses an HVAC system and/or high powered fans to move large quantities of air and dilute contaminants based on an air change schedule. Dilution ventilation is comprised of fans such as roof exhaust fans and wall fans. A dilution ventilation system uses large amounts of air to flush out the whole area and dilute contaminants to the concentrations below prescribed limits. However, it allows the contaminants to enter the welder’s breathing zone before the contaminants are removed from the working environment. If used exclusively, dilution ventilation may not be adequate to control the exposure of welders to welding fumes and gases to below the permissible occupational exposure limits.
- Removes contaminants from the entire facility
- Used where local ventilation is not practical
- Does not always protect the immediate worker’s breathing zone
2. Local Exhaust Ventilation
Local Exhaust Ventilation is an engineering control that captures and removes contaminants at their source, before they reach a worker’s breathing zone. Some welding equipment comes equipped with local exhaust ventilation attached to the welding equipment and is designed to remove the fumes and gases close to their point of origin. Other local exhaust ventilation systems are comprised of a hood, fan, duct, and air cleaner. The local exhaust ventilation must be designed and installed in such a way that welding fumes and gases are prevented from entering the welder’s breathing zone. For fixed enclosures, local exhaust must be installed such that the fumes and gases are drawn away from the welder’s breathing zone.
- Captures and removes contaminated air at the source before reaching a worker’s breathing zone
- Hooded systems are less feasible on large weldments with no fixed position
There are four types of engineered local exhaust ventilation systems:
- A welding bench with a fixed hood
- A down-draft bench
- A portable hood with flexible ducting
- A fume extraction gun or gun attachments with flexible ducting
- Can the extraction hood get close enough to the source unobstructed?
- Is the capture velocity enough to move the fumes away from the welder?
- Is the extraction device portable enough to reach all portions of the weld when working?
Recommended Hood Positioning:
- When using a movable hood, position it above the arc and angled at approximately 45° so that the fume is pulled away from the breathing zone
- The hood distance will vary depending on the velocity and volume of air movement into the extraction device
- In general it’s approximately the distance of 1 ½ duct diameters away
Recommended Air Velocity:
An air velocity of 0.5 m/s (100 ft/min) across the welding site is recommended. In all processes that use shielding gases, air velocities in excess of 0.5 m/s may strip them away. For down-draft benches, it is necessary that an air velocity be great enough to assure that the fumes and gases generated during welding do not rise into the breathing zone of the welder. In addition, the welder must know that if the work pieces cover too much of the down-draft hood assembly the exhaust effect is lost.
Dust and Fume Extraction Systems
MultiCam Canada is proud to partner both Eurovac and Sideros Engineering, two leading Dust and Fume Extraction Systems manufacturers. MultiCam can offer an extraction system to fit your unique needs based on volume, contamination level, space constraints, and other factors.
MultiCam Canada is a licensed distributor of the complete line of Eurovac high volume dust and fume extraction systems. For those manufacturers requiring systems to treat highly contaminated air volumes, but don’t have the shop-floor space for large bulky units, then Eurovac has an extraction system to fit your needs.
MultiCam Canada is a licensed distributor of the complete line of Sideros dust and fume extraction systems as well as their welding positioners. Sideros Engineering have been specialists in suction tables and cartridge dust collectors for thermal cutting since 1981.
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