Page 30 - Occupational Health & Safety, May 2017

INDUSTRIAL HYGIENE/WELDING
mately 0.1 to 0.3 microns). This is similar to the High-Efficiency Particulate Air (HEPA) filter on a vacuum cleaner. Our weld fume control products utilize one or more of these filter types, depending on the model.
2. When should you replace the filter?
Over time, a filter may become saturated with particulate mat- ter. Once this happens, the filter needs to be replaced. Certain in- dicators will signal the need for a filter change. Some are specific to your fume extraction system itself. Others are related to the welding materials you are using and/or the ambient conditions in the manufacturing environment. Here’s what to look for and be aware of:
■ The need for filter replacement is typically indicated by a gauge, an audible tone, an indicator, or a combination of these, depending on the features of the system. Always reference the in- struction manual to find the indicator mechanism on your extrac- tion unit. You may also notice a decrease in extraction capacity and possibly a reduction in extraction of welding fume if the filter has become oversaturated and is not changed.
■ The rate of welding fume generation may vary based on the welding processes that are used in your operation and the particular welding settings selected. The choice of shielding gases, where applicable, also can influence fume generation. Stick and flux-cored welding tend to generate a higher volume of fume compared to MIG welding and TIG welding, which typically
26 Occupational Health & Safety | MAY 2017 Untitled-4 1
generate less particulate than the other processes. The welding process and settings used may impact the life expectancy of your filter, and you should take them into account when you are set- ting up your replacement schedule.
■ Another factor that will help you anticipate the need to re- place your filter includes how many hours and shifts you system is operating. The more hours and shifts worked, the sooner the filter needs replaced.
■ Changes in climate or the environment may warrant a filter check and replacement. When companies do extensive mainte- nance in the summer months, it’s a good time to schedule a re- placement of filters. In the fall and winter months, when windows and doors are closed due to cooler weather, it is a good reminder to make regular checks to ensure that the exhaust systems are func- tioning properly.
3. What filter should you use?
While the importance of replacing filters may seem obvious, it works only if you select the appropriate replacement filter for han- dling weld fumes.
First, ensure your replacement filters meets welding ventilation requirements established by OSHA and the EPA at the local, state, and federal levels.
Second, confirm your replacement filter has the right MERV (Minimal Efficiency Reporting Value). The industrial air filtration industry offers numerous choices of filters—so determining the
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