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In-depth survey report: evaluation of local exhaust ventilation system for the 010 culling system at United States Postal Service, Merrifield Processing and Distribution Center, Merrifield, Virginia, Report No. CT-279-14a1.

Topmiller-JL; Crouch-KG; Beamer-B
NIOSH 2003 Jan; :1-11
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 sorting system - the 010 Culling System. The ventilation control system 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 processed by the equipment. This effort is in response to recent 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. The 010 Culling System consists of 2 conveyor systems that size collection mail. The first is the Dual Pass Rough Cull (DPRC), and the second is the Loose Mail Distribution System (LMDS). Evaluations were based on a variety of tests including tracer gas experiments, air velocity measurements, and smoke release observations. The experiments showed that generally there is good capture by the ventilation system, however, there are some points that require improvement. Results of tracer gas tests showed capture efficiencies exceeding 95% for the majority of the positions tested. The bypass chute for the LMDS showed poor control (68%) as did the exhaust on belt LL-7 (82%). The other areas of poor control were the flats extractors from the DPRC lines 1 and 2 (23% and 48%, respectively), and the letter channel drop (49%). Smoke release observations and air velocity measurements support these results. Smoke tests also revealed an open area near the hamper dumper for the LMDS above the cull belt that was not controlled. Based on these results as discussed in this report, the following recommendations are made to further improve the control of potential contaminants by this mail sorting system: (1) improve the ventilation on the letter channels exiting the waterfall area of the DPRC, particularly near the ends where the mail pieces undergo the most agitation, (2) add exhaust to the area above the cull belt just after the hamper dumper, (3) improve the ventilation for the flats extractors on the DPRC, and (4) redesign the exhaust hood for the letter channel drop. The hood face was covered with mail during operation, preventing the hood from operating properly.
Postal-employees; Materials-handling-equipment; Gas-detectors; Ventilation; Ventilation-equipment; Ventilation-hoods; Ventilation-systems; Engineering-controls; Environmental-control-equipment; Exhaust-hoods; Exhaust-systems; Control-technology; Region-3; Microorganisms; Biological-weapons
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Field Studies; Control Technology
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National Institute for Occupational Safety and Health