An evaluation of catalytic emission controls to prevent carbon monoxide poisonings from houseboat generator exhaust
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An evaluation of catalytic emission controls to prevent carbon monoxide poisonings from houseboat generator exhaust

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    "Working under an interagency agreement with the United States Coast Guard, researchers from the National Institute for Occupational Safety and Health (NIOSH) evaluated carbon monoxide (CO) emissions, exposures, and controls from gasoline-powered generators on houseboats. This evaluation was part of a series of studies conducted by NIOSH investigators during the past several years to identify and recommend effective engineering controls to reduce the CO hazard and prevent CO poisonings on houseboats and other recreational marine vessels. The performance of two (20 KW and 14 KW) Westerbeke Safe-CO(TM) generators were tested after being used on rental houseboats for two full boating seasons. The evaluated generators had 2,835 and 4,656 hours of use respectively and were equipped with catalytic converters and electronic fuel injection systems. A 12.5 KW Westerbeke generator was also tested that had been retrofitted with a Zenith electronic fuel injection (EFI) retrofit kit. Each of the engineering control devices were designed to improve generator performance and reduce CO emissions. The houseboat containing the 14 KW generator had been modified so that testing could be accomplished using either a side exhaust or stack exhaust configuration. The two Westerbeke Safe-CO(TM) generators used for two boating seasons performed well; average CO concentrations at various locations on the boat were generally below 5 parts per million (ppm). Peak CO concentrations were all well below 10 ppm. Both old and brand new catalysts were evaluated for the 14 KW generator. The new catalysts performed much better than the one used for two seasons. Degradation of the catalyst was observed on the 14 KW unit that had 4,656 hours of use. This generator was unable to keep CO concentrations below 4,000 ppm under load when measured directly in the exhaust plume. When the catalyst was replaced, the generator again performed according to its design criteria. CO concentrations were lower under the no-load conditions as compared to load conditions when measurements were collected directly in the exhaust plume. CO concentrations measured directly in the exhaust stack were below 1,000 ppm for the fully warmed generator. That compares to CO concentrations NIOSH researchers measured which usually exceeded 10,000 ppm on older Westerbeke generators without the Safe-CO(TM) control systems. When comparing side versus stack exhaust, the lower stern deck in the side exhaust configuration resulted in slightly higher concentrations. Use of the Safe-CO(TM) generator resulted in low ambient CO concentrations for both side and stack exhaust configurations. It is important that the boater/owner/operator follow all of the maintenance recommendations provided by the manufacturer. Some of those recommendations include periodically changing the oxygen sensor in the generator and replacing the catalyst every 2,000 hours. Use of the vertical exhaust stack with the Safe-CO(TM) generator is recommended to ensure redundancy in the system in the event of catalyst degradation or oxygen sensor malfunction. Development and commercialization of these systems is a major step forward in control systems to ensure a safe environment around houseboats and other marine vessels. 5 The performance of the Westerbeke generator retrofitted with a Zenith EFI system was also an improvement when compared with old, non-EFI systems. CO concentrations measured on the boat were also typically below 5 ppm; however, the CO concentrations measured directly in the exhaust were higher than the Safe-CO(TM) generators. The Zenith EFI system did not perform as well when the generator was under load; CO concentrations measured directly in the exhaust were substantially higher. CO concentrations measured directly in the exhaust stack were constantly above 10,000 ppm when the generator was under load conditions." - NIOSHTIC-2;NIOSHTIC no. 20032418;
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