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首页> 外文期刊>American Industrial Hygiene Association Journal >Evaluation of leakage from a metal machining center using tracer gas methods: a case study.
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Evaluation of leakage from a metal machining center using tracer gas methods: a case study.

机译：使用示踪气体方法评估金属加工中心的泄漏：一个案例研究。

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摘要

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.
机译：为了评估工程控制在减少工人接触金属加工液方面的功效，对端面铣削过程中的加工中心外壳进行了评估。外壳围绕一个垂直金属加工中心建造，带有一个通风系统，该通风系统由直径为25厘米的管道，风扇和空气过滤器组成。评估方法包括使用六氟化硫（SF6）示踪气体确定通风系统的流速和捕集效率，可呼吸的气溶胶监测器（RAM）来确定机壳周围的气溶胶泄漏位置，烟管和测速仪以评估周围的空气运动。外壳的外部。示踪气体评估结果表明，该控制系统在捕获在加工中心主轴附近释放的示踪气体的效率约为98％。该结果与100％效率无显着差异（p = 0.2）。当直接释放到管道中时，测得的SF6浓度的相对标准偏差为2.2％。而当在纺锤体上释放SF6时，该浓度的相对标准偏差明显更高，为7.8％（p = 0.016）。这种增加的可变性可能是由于外壳上部和下部之间的小间隙处的周期性泄漏或由于循环停滞。还通过烟管，测速仪和气溶胶光度计观察到泄漏。工具和流体的运动相结合以引起周期性的气流进出外壳。这些结果表明，示踪气体方法可用于评估围护效率。但是，还需要使用烟管和气溶胶仪器（例如，光学粒子计数器或气溶胶光度计）来定位外壳的泄漏。

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