Page 28 - Occupational Health & Safety, May 2017

INDUSTRIAL HYGIENE/WELDING
ClearingtheAir:TheImportanceofFilterReplacement for Welding Fume Extraction Systems
For as much as you might be tempted to cut costs, filter replacement isn’t a good place to do it. Not all replacement filters are alike, even if they are specifically designed to fit your system.
BY JASON A. LANGE
24 Occupational Health & Safety | MAY 2017
www.ohsonline.com
The purpose of a filter in a welding fume ex- traction system is to capture and remove airborne particulates from the workplace environment. Mechanical filters incorpo- rate a filtering medium made from microscopic fi- bers (fiberglass, cellulose, or polyester fibers, etc.) woven in sheets and typically pleated in a “V” pat- tern. The pleating of the material increases the sur- face area of the filter providing an increased capture surface. This white paper discusses several impor- tant factors about filter replacement for a welding fume extraction system.
1. What are the types of mechanical filters, and what do I need to know about each?
There are three basic types of filters used in weld- ing fume extraction systems. Each performs a specific function:
Pre-filter. The purpose of a pre-filter is to cap- ture larger particulates and remove them from the system so they do not reach the main filter. The pre- filter is typically made from aluminum or steel mesh and may also act as a spark arrestor.
■ Main filter. The main filter is designed to cap- ture the majority of the particulates generated from welding and its allied processes. Mechanical filtration can also be used effectively for the grinding process.
■ After filter. The purpose of the after filter is to filter out any remaining small particulates (approxi-
■
LINCOLN ELECTRIC