Page 44 - OHS, Feb/Mar 2024

WELDING work areas may have more complex airflow patterns, and it may be necessary to strategically position multiple ventilation devices to ensure thorough fume control. Robotic weld cells come in both large and small booths, either enclosed or open-top. Large robotic welding operations can also involve a traveling robot that moves from one end of the cell to the other. 8. Handling the Collected Air Welding facility operators also must consider whether the collected air will be cleaned and returned into the facility or exhausted outside. Recycling the air may require using a secondary high-per- formance filter with the dust collection system, such as a HEPA filter in order to maintain OSHA PELs for the indoor workplace air. This can be done with an integrated safety monitoring filter system, which is contained in the footprint of the primary dust collector filter housing. Another option is to use a remote moni- toring filter system that is a separate housing in line with the duc- twork downstream from the main filter housing. Welding shop operators that choose to exhaust fumes outside are particularly at risk of being in violation of the NESHAP Rule 6X EPA requirement. Older dust collection equipment or HVAC filtration units used to clean the air can also lead to non-compli- ance if they are not properly designed to handle the process fumes or are using older filter technology. 9. Type of Capture Needed Hood and source capture systems work well for smaller operations with booth-style setups and welding smaller products. These sys- tems are commonly applied to applications with stainless steel or galvanized welding processes. Portable units can be used at a mini- mum and should be limited to small processes in the facility. For welding operations beyond small-job welding projects, a portable unit will not keep up with fume production, and it eventually will stop being effective, get pushed to the side and not used at all. Assess sparks and possible filter ignition sources to prevent fires in the dust collection equipment. Spark arrestors can be add- ed to address this issue. Ambient dust collection systems are frequently used in ex- pansive workspaces where various operations are conducted. A central unit or multiple smaller collectors filter all the air within the workshop. They can be designed around bridge cranes and overhead equipment. While these systems effectively manage air- borne particles within the whole room, it is important to note that they do not eliminate fumes from the welders’ immediate breath- ing zone. Consequently, workers may need to utilize PPE or use fans to redirect fumes away from their working area. Ambient systems can be used to push hot air out of work areas that do not have air conditioning. They also help to reduce energy costs by recycling heated or cooled air into the facility. 10. Fume Collector Sizing Airflow and air exchange are important considerations in con- trolling weld fumes. Air changes per hour is a calculation of how many times per hour the entire volume of air in a given space is replaced with supply and/or recirculated air. A good starting point is eight to ten air changes per hour in the welding area. If smoke is heavy or plasma cutting and other grinding processes Welding shop operators must control smoke and particulates to protect the health of workers and to comply with regulations. are performed in the area, use faster air change times and lower air-to-cloth filter media ratios (the volume of air flowing through each square foot of filter media every minute). Low ceilings and smaller rooms concentrate smoke and fumes quicker, so more air changes per hour will be needed. Medium to light smoke in an area with a very high ceiling might be con- trolled with fewer air changes per hour. In addition to airflow in the room, consider factors such as ceiling fans, open doors, HVAC-conditioned air entering and leaving the room, as well as individual work area comfort fans. These efforts can all affect how smoke and fumes travel through a room or facility and should be taken into account when evaluat- ing where and how air is collected from the area. When using an ambient type of collection system, it is imperative to know how your building works in the summer and winter time. Key ques- tions to answer are: what type of heating system is used, what type of air conditioning system is used, and if there is no air condition- ing, where are the exhaust fans and intake louvers located? Ceilings also play an important role in controlling airborne particulates. Welding fumes will rise along sloped ceilings. Utiliz- ing the higher points in a building’s roof area will help to ensure successful capture of the smoke. Use of ceiling-to-floor curtains around the perimeter of weld areas or booths can help to contain smoke in a collection area if needed and can be used to isolate areas in large plants. Wide, clear, solid panels situated around the welding cell can also help with welding flash protection for employees in the area. Locating the smoke and fume collector outdoors not only saves floor space, it is safer with regard to fire protection. Summing It Up Maintaining healthy, compliant indoor air quality in welding facilities is a necessary component to a properly run operation. A well-designed weld fume and smoke collection system will change the accepted clean air culture in an industry setting. Em- ployees will embrace the change it makes in their lives and will be the first to raise the flag when the system is not doing its job. Brian Richardson is the Northwest Regional Sales Manager for Camfil Air Pollution Control, manufacturer of dust and fume col- lection equipment for challenging industrial applications. For more information call (800) 479-6801, email filterman@camfilapc.com or visit camfilapc.com. 42 Occupational Health & Safety | FEBRUARY/MARCH 2024 www.ohsonline.com Photo courtesy of Camfil Air Pollution Control