Evaluation of a high-efficiency, filter-bank system

Area of Science:

• Occupational Health and Safety
• Environmental Engineering
• Filtration Technology

Background:

• Following the 2001 anthrax attacks, U.S. Postal Service (USPS) facilities installed new ventilation and filtration systems (VFSs).
• These systems incorporated high-efficiency particulate air (HEPA) filters, mandated by USPS contract specifications for superior particle capture.
• The USPS required a minimum filtration efficiency of 99.97% for particles sized between 0.3 and 3.0 micrometers.

Purpose of the Study:

• To evaluate the filtration efficiencies of installed VFSs in USPS facilities.
• To adapt and validate a modified methodology for assessing total filtration system performance.
• To identify VFSs meeting USPS performance criteria and those requiring maintenance or replacement.

Main Methods:

• Investigators modified a methodology originally developed for testing agricultural tractor cab enclosures.
• The modified sampling strategy was employed to assess the overall filtration system efficiency of the VFSs.
• Careful selection and matching of optical particle counters immediately prior to testing were crucial for accurate results.

Main Results:

• The modified methodology successfully monitored the total filtration system component of VFS performance.
• The evaluation effectively distinguished between VFSs meeting the high USPS performance standards and those needing repair.
• The study underscored the critical importance of properly matched optical particle counters for reliable testing.

Conclusions:

• The adapted methodology is a reliable tool for evaluating VFS performance in USPS facilities.
• This approach is adaptable for assessing various workplace air filtration systems, including high-efficiency units.
• Ensuring proper VFS maintenance and performance is vital for maintaining a safe working environment.