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A demonstration of NIOSH push-pull ventilation criteria.

Am Ind Hyg Assoc J 1987 Mar; 48(3):238-246
The results of a study of a push pull (PP) ventilation system on a chrome plating tank were summarized. The design of the demonstration tank was similar to that of the laboratory tank developed by Huebener and Hughes. The initial push and pull settings were, respectively, 0.034 cubic meters per second per meter (m3/sec/m) and 0.36 cubic meters per second per square meter (m3/sec/m2). Also included in the tests was the lowest possible push setting of 0.22m3/sec/m. Industrial hygiene samples were taken for hexavalent chromium (18540299) (Cr(VI)) and total chrome (7440473). The process operating parameters were checked every hour during production and dummy runs. The PP system at the study setting controlled the total chrome emissions from the plating process to below the OSHA standards and the NIOSH and ACGIH guidelines. The overall Cr(VI) levels were below the OSHA and ACGIH limits but exceeded the NIOSH recommendations for the two lower push settings. However, the PP system was believed to have controlled Cr(VI) levels to within the NIOSH levels, because the samples were collected near the tank under heavier exposure conditions than would be experienced by workers. The Statistical analysis of the data showed the ability of the PP system to compensate for interferences in the flow of the push air. The lack of significant differences between production run and dummy loads indicated that evaporation from the plated parts and baskets, when they were out of the tank, did not affect air concentration significantly. The system worked at a push setting lower than the range found by Huebener. The author states that adjustments to Huebener's results are needed to compensate for different nozzle construction and environmental conditions.
NIOSH-Author; Industrial-processes; Industrial-ventilation; Chrome-plating; Chromium-compounds; Industrial-hazards; Industrial-exposures; Toxic-vapors
18540-29-9; 7440-47-3
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American Industrial Hygiene Association Journal