01 Sep Proper Air Filtration in Welding Shops – What do the regulations require?
Welding produces off-gassing that can be hazardous to a welder’s health. Whether its stick, tig, mig, or other types of welding, gas and fumes are produced in the process that enters the air right at the source of the weld – exactly where the operator is breathing and working. The question is: how is your shop ensuring clean air for your welders to breath?
Manitoba, through Safe Work Manitoba, has recently implemented regulations significantly reducing the acceptable limits of manganese in the air (similar regulations are in place in the US) in the workplace. Through a two-year study, they found significant benefits from proper air filtration and removal in the welding process and the regulations restricting manganese was quickly adopted. As lung problems, such as metal fume fever, are very common in welders, Safe Work Manitoba decided to implement these regulations to protect workers’ health and to ensure safe working environments. Businesses who are found to have higher than acceptable levels are currently being issued improvement orders. For business, this means that developing air quality solutions in the workplace is now a top priority.
What weld smoke removal options are there?
Prevention, through proper air extraction and filtration, is the key component to reducing Occupational Exposure Limits (OELs). OEL’s are the maximum permissible concentrations of a hazardous substance (levels determined by government workplace safety regulations) that most healthy adults may be repeatedly exposed to without suffering adverse health effects. Remember, these limits assume the individual exposed to the substance is a healthy adult. There may be increased risk, for example, for a smoker, a person with pre-existing health problems or individuals who suffer from allergies.
And it’s not just the metals giving off pollutants and chemical irritants – coatings, paints, and residual solvents that are on many metals can also produce toxic pollutants in the air. Additionally, welding is sometimes performed in tight or enclosed spaces, magnifying the exposure of the welder to the toxic gases.
Weld smoke is one of the most common detriments to a workers health as most welding jobs can be completed without air purification. It’s seen as extraneous, which couldn’t be further from the truth. Employers and employees alike need to be aware of the long term damage this can cause to one’s health.
Welders can reduce exposure to welding fumes and gasses in one of four ways: introducing environmental controls (enclosures, filtration, and improved ventilation), implementing work-rest schedules and safe-work practices, wearing respiratory protection, and substituting less hazardous flux materials. For our purposes, and since it is our specialty, we’re going to focus on air filtration and improved ventilation in this post.
Here are some important points to know in regards to air filtration for welding:
The Airborne Pollutants – Gases and Fumes
All welding processes produce hazardous gasses. Gasses are invisible to the eye, and may or may not have an odour. The heat in both the flame and the arc, and the ultraviolet radiation from the arc, produce gases such as carbon monoxide, carbon dioxide, oxides of nitrogen and ozone. Other gasses and vapours may be produced as by-products from the breakdown of solvents or coatings on the metal. Gasses used for arc shielding, or as a fuel, are also given off during welding.
Fumes, on the other hand, are incredibly small, solid particles in the air. Fumes are formed when hot metal vapours cool and condense into very small particles that stay suspended in the gas. The particles may be metal or metal compounds, and are often smaller than one micrometre (one-fiftieth the width of a human hair). Fumes may not be visible to the eye but even if fumes can’t be seen, its particles can still be present. Of major concern in welding fumes is chromium hexavalent Cr(VI) compounds. Industrial uses of hexavalent chromium compounds include pigments in dyes, paints, inks, and plastics; chromates added as anticorrosive agents to paints, primers, and other surface coatings; and chromic acid electroplated onto metal parts to provide a decorative or protective coating. These compounds are particularly hazardous and are recognized as a known carcinogen and is linked to many other health concerns for welders.
Whatever process used in your shop to remove toxic air it must consider both gas and fume filtration/extraction.
Good, Better, Best Options for removing harmful weld fumes and gases.
Exhaust and Filtration
The first basic option is to filter all of the circulated air as it is exhausted to the outside of the facility. This method has lower upfront costs and accomplishes the goal of worker safety. However; in the long term, it is generally more expensive due to energy costs of constantly heating new air entering the building. Also, by exhausting your conditioned air, makeup air units would need to be installed to reduce negative air pressure in the facility. The downside of this is that the filtration and exhausting take time and airborne pollutants may not be extracted fast enough.
Typically on the prairies the air isn’t filtered before it is exhausted, it would just be blown straight to the outside and fresh air would be brought in at an opposite point in the area (different provinces and states have different regulations concerning air ventilation and filtration, please consult your local building code for specifications or ask us to come in and consult on your needs).
Ambient Air Collection and Filtration
Filtering the ambient air (keeping all the air in the area) through an environmental filter system accomplishes the goals of worker safety without exhausting the air to the outside. This method is a better option than exhausting from an overall cost perspective and where source capture is impractical due to obstacles in the workplace, the layout of the facility, or budgetary constraints, it may be your best option. In this scenario, filtering would take place when the air in the application is pulled into the filtering device and released back into the same environment at a different location. This reduces air heating costs as the return air maintains its temperature while being filtered.
Alternatively, there are large, outdoor units that take air from the inside of a facility, filter it outside, and send it back into the facility. The benefit of which is that the captured particles are stored in bins, outside, ready for disposal.
As with any system that affects the air in the facility these systems, it takes time to effectively filter the air in the environment and dependent on specific needs, may not be sufficiently fast enough at filtering the air for your operator health concerns.
Source Capture Filtration of Welding Gases
As the name implies, pollutants are captured as close to the welding process as possible (weld smoke filtration). Through the use of hoods, enclosures, and airflow, source capture provides the most effective means of controlling pollutants. Fumes and gasses are pulled away from the worker at the source and filtered as needed. This is one of the best options as it is in operation only during the times it is needed and pollutants don’t have a chance to drift throughout the plant before being filtered.
Filters – the critical factor
The filters you use in any system should be chosen based on the fumes, dust, and gasses produced. There is a wide selection of filters available but the proper selection is critical to the effectiveness of your clean air system. The wrong filter is simply a waste of money and may not extract the pollutants in your environment from the air. Also, a filter that is plugged isn’t doing its job, remember to replace filters as per the manufacturers’ guidelines (or more frequently depending on your operation). This is where a conversation with your Acculift sales representative can maximize efficiency and minimize ongoing expenses.
The importance of proper ventilation while welding cannot be stressed enough. To find out more, the Canadian Centre for Occupational Health and Safety outlines the hazards of welding off-gassing here and the Alberta government provides this documentation that is worthwhile for all welders to read.