Evaluation of Leakage from a Metal Machining Center Using Tracer Gas Methods: A Case Study
| Autor: | Mead Kr, Earnest Gs, Mickelsen Rl, D'Arcy Jb, William A. Heitbrink |
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| Rok vydání: | 1999 |
| Předmět: |
Aerosols
Leak business.industry Nuclear engineering Sulfur Hexafluoride Public Health Environmental and Occupational Health Electrical engineering Enclosure Air Pollutants Occupational Risk Assessment Ventilation Aerosol Sulfur hexafluoride chemistry.chemical_compound Machining chemistry Air Pollution Indoor Occupational Exposure TRACER Metallurgy Humans Environmental science Working fluid Duct (flow) business |
| Zdroj: | American Industrial Hygiene Association Journal. 60:785-788 |
| ISSN: | 0002-8894 |
| DOI: | 10.1080/00028899908984502 |
| Popis: | To evaluate the efficacy of engineering controls in reducing worker exposure to metalworking fluids, an evaluation of an enclosure for a machining center during face milling was performed. The enclosure was built around a vertical metal machining center with an attached ventilation system consisting of a 25-cm diameter duct, a fan, and an air-cleaning filter. The evaluation method included using sulfur hexafluoride (SF6) tracer gas to determine the ventilation system's flow rate and capture efficiency, a respirable aerosol monitor (RAM) to identify aerosol leak locations around the enclosure, and smoke tubes and a velometer to evaluate air movement around the outside of the enclosure. Results of the tracer gas evaluation indicated that the control system was approximately 98% efficient at capturing tracer gas released near the spindle of the machining center. This result was not significantly different from 100% efficiency (p = 0.2). The measured SF6 concentration when released directly into the duct had a relative standard deviation of 2.2%; whereas, when releasing SF6 at the spindle, the concentration had a significantly higher relative standard deviation of 7.8% (p = 0.016). This increased variability could be due to a cyclic leakage at a small gap between the upper and lower portion of the enclosure or due to cyclic stagnation. Leakage also was observed with smoke tubes, a velometer, and an aerosol photometer. The tool and fluid motion combined to induce a periodic airflow in and out of the enclosure. These results suggest that tracer gas methods could be used to evaluate enclosure efficiency. However, smoke tubes and aerosol instrumentation such as optical particle counters or aerosol photometers also need to be used to locate leakage from enclosures. |
| Databáze: | OpenAIRE |
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