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In-Depth Survey Report: Evaluation of Ventilation/Filtration System for the 010 Culling System at United States Postal Service, Cleveland Processing and Distribution Center, Cleveland, Ohio
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2004/03/01
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Description:Researchers from the National Institute for Occupational Safety and Health (NIOSH) conducted an evaluation of the Ventilation/Filtration System (VFS) developed for the United States Postal Service (USPS) mail processing equipment - the 010 Culling System. The VFS was developed and installed by a private contractor hired by the USPS to reduce the potential for employee exposure to harmful substances that could be contained in mail pieces processed by the equipment. This effort is in response to the 2001 terrorist attacks that used the mail as a delivery system for anthrax. NIOSH was asked to assist the USPS in evaluating controls for this and other mail processing equipment. Evaluations were based on a variety of tests including: tracer gas (TG) experiments, air velocity measurements and smoke release observations to evaluate contaminant capture efficiency, as well as simultaneous particle count experiments upstream and downstream of the VFS filtration to evaluate system filtration efficiency. The experiments showed that the system met or exceeded minimum contaminant capture velocities (100 feet per minute), except at the Waterfall areas. Lower capture velocities at the Waterfall areas, however, were mitigated by the fact that: these areas are largely enclosed
tracer gas capture at these areas met acceptance criteria and
smoke release observations indicated good contaminant capture. It should also be noted that "dirty filter" testing showed that capture velocities were relatively unchanged at several key locations when the air handling units operated at lower capacities (in order to simulate loaded/"dirty filters"). Additionally, contaminant filtration capabilities met or exceeded the 99.7% filtration efficiency requirement at Air Handling Units 2 and 3. Moreover, test results at Air Handling Unit 1 showed that the filtration efficiency was at least 99.97% after vendor modifications were made to the system. Based on the results as discussed in this report, the following comments summarize the effectiveness of the Ventilation and Filtration System: Capture Capabilities - 1) Overall, testing showed that contaminant capture capabilities met or exceeded USPS requirements. 2) The high volumes of air being entrained into the VFS exhaust at the flats extractors and at the conveyor immediately leading to the AFCS occasionally resulted in partial clogging of the VFS exhaust air intakes. 3) This condition did not necessarily lead to inadequate performance of the VFS
however VFS performance would be optimized if an engineering solution were developed to prevent the blockage of VFS exhaust intakes. 4) The vendor of the VFS is aware of this situation and is enhancing the system to eliminate such blockage. 5) "Dirty filter" testing, in which capture velocity measurements were made at several locations at reduced VFS air flows in order to simulate loaded/dirty filters, showed that capture velocities were relatively unchanged under these conditions. 6) Lower capture velocities at the Waterfall areas were mitigated by the fact that these areas are largely enclosed
tracer gas capture at these areas met acceptance criteria
and smoke release observations indicated good contaminant capture. Filtration Capabilities - 1) The modifications made to 010 VFS Unit # 1 prior to meeting the 99.97% efficiency requirement should be made a permanent change to the manufacturing process of that unit. The vendor has acknowledged this situation and has made the necessary enhancements. 2) Tests conducted with AAF HEPA filters and Donaldson HEPA filters in 010 VFS Unit # 1 show filters are interchangeable. 3) Extreme care should be taken when performing any maintenance on any VFS, particularly any operation that could disturb the seal of the filters inside the VFS housing. 4) Real- time total system integrity testing is the only reliable test method for evaluating total system filtration performance. 5) It is recommended that the USPS should implement a system to routinely test the system filtration efficiency of all units. As was demonstrated in this research, small leaks and perforations in the filter media can easily breach system integrity.
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Pages in Document:1-21
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Contributor:Hammond, Duane R.
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NIOSHTIC Number:nn:20024596
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NTIS Accession Number:PB2004-105240
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Citation:Cincinnati, OH: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, EPHB 279-20a, 2004 Mar;:1-21;
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Federal Fiscal Year:2004
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Peer Reviewed:False
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[PDF-463.12 KB]